- Blueberry Gardener’s Guide1
- Site Requirements
- Planting and Establishment
- Weed Control
- Pests and Diseases
- Blueberry Plants Not Producing – Getting Blueberries To Bloom And Fruit
- Help for Blueberries Not Fruiting
- Additional Reasons for Blueberry Plants not Producing
- Selecting Blueberry Varieties for the Home Garden
- Recommended Varieties
- Plant Growth Cycle & Yields
- Blueberries: Origins – Consumption – Nutrition Facts – Health Benefits
- Geographic Origins and Regions Grown
- History of Consumption
- Common Consumption Today
- Nutrition Facts: Vitamins, Minerals and Phytochemical Components
- Health Benefits: Medicinal Uses Based on Scientific Studies
- Didn’t find what you were looking for? Search here…
- Food Articles, News & Features Section
- BLUEBERRY HISTORY
- HISTORYNative American Tradition
Blueberry Gardener’s Guide1
J. G. Williamson, P. M. Lyrene, and J. W. Olmstead2
The purpose of this publication is to provide home gardeners with basic information on growing blueberries in Florida. Commercial growers and those interested in more detailed information on growing blueberries in Florida are encouraged to visit the UF/IFAS Extension publications website at http://edis.ifas.ufl.edu/topic_blueberry.
Florida’s winter season is short and mild with intermittent periods of warm temperatures. Most deciduous fruit cultivars have high chilling requirements and do not grow well in Florida. To produce optimum fruit yield and quality, most deciduous fruit cultivars require more exposure to temperatures below 45ºF during the winter than they are likely to experience in Florida. With insufficient chilling, plants do not flower and leaf out satisfactorily during the spring. Growth can be weak and erratic. However, low-chill cultivars of some deciduous fruits, including blueberry, have been developed by plant breeders at the University of Florida and elsewhere. These cultivars were developed specifically for regions with mild winter temperatures such as in north and central Florida.
Two types of blueberries grow well in Florida, rabbiteye (Vaccinium virgatum) and southern highbush (interspecific hybrids of V. darrowii, V. virgatum, and V. corymbosum). However, only the low-chill cultivars of each are adapted to Florida. Generally, rabbiteye blueberries grow well in areas of Florida that have winters as cold as or colder than winters in Ocala. The southern highbush cultivars that are commonly grown in Florida are well adapted to areas south of Ocala and north of Sebring, although they will grow reasonably well in Alachua County. The southern limits of southern highbush adaptation in Florida have not been fully determined.
Both rabbiteye and southern highbush thrive on acidic soils, which contain more organic matter than is usually found in Florida soils. If mulched, rabbiteye blueberries will usually grow satisfactorily on soils with 1% organic matter, but they perform better with soils that have 2–3% organic matter. Southern highbush cultivars are not recommended for soils with less than 3% organic matter unless additional organic matter is added as a soil amendment and mulches are added to the site. Peat moss or pine bark is commonly used to increase soil organic matter in blueberry plantings. Peat moss can be incorporated into the soil at or prior to planting. Pine bark can also be mixed into the soil, or when applied as mulch it will eventually decompose and add to the soil organic matter content. In areas where blueberry plants have been heavily mulched for several years, it is not uncommon to observe most of the fibrous roots growing in the decomposed litter above the natural soil.
Blueberries require a soil pH of 4.0–5.5. At higher soil pH values, tissue levels of microelements such as iron and zinc become deficient. Deficiency symptoms develop on new growth, and plants lose vigor. Soil can be acidified by thoroughly mixing a small amount of granulated sulfur into the soil several months before planting. Many fertilizers are acid-forming and will gradually lower the soil pH. A soil test is needed to measure the soil pH and can help to determine whether or not acidification of the soil is necessary. Your local county Extension office can assist you with proper soil testing procedures.
Blueberries require a well-drained soil profile of at least 18 inches in depth. Blueberries should be planted on raised beds if water drainage is poor (within 18 inches of the soil surface for prolonged periods during the rainy season). If blueberry roots are exposed to water-saturated soil for more than a few days, damage from Phytophthora root rot may become severe. Generally, blueberries will grow well where azaleas, camellias, and other “acid-loving” plants are proven performers.
Set plants in a sunny area (at least 4–5 hours of full sun per day) away from the roots of trees except pines and at least 20 feet away from any building foundation. A mature rabbiteye blueberry plant can reach 12–15 feet in height with canes sprouting over an area of 8–10 feet in diameter. Southern highbush plants tend to be less vigorous and smaller than rabbiteyes. Plant size can be controlled to some degree by pruning. However, severe pruning will reduce yields the following spring. Allow at least a 7′ x 7′ area for rabbiteyes and a 4′ x 4′ area for southern highbush. Plants may be set 3 feet apart (southern highbush) or 5 feet apart (rabbiteye) for a hedgerow effect.
Planting and Establishment
The best time to plant blueberries is from mid-December to mid-February. Bare-root or container-grown plants can be used. It is best to use plants about 1.5 to 2 feet tall with well-developed root systems that are not pot-bound. Keep the roots of bare-rooted plants moist but not overly wet prior to and during planting. The root balls of potted plants should be broken up slightly and the roots of bare-rooted plants should be spread out evenly in the planting hole. In most situations, dooryard blueberry plants benefit from the incorporation of 1/4–1/2 cubic foot of acid sphagnum peat moss into the planting hole. Dig the hole large enough to accommodate the roots and peat moss. The plants should be set at the same height as when they were growing in the nursery. If blueberries are planted on raised beds, flatten the bed in the vicinity of the plants and set the plant in a slight depression so that irrigation and rain water will not flow away from the plant.
Pine bark mulch aids in the establishment of young blueberry plants. Either a layer of pine bark 3 inches deep extending about 2 feet out from the plants in all directions or a pine bark strip about 4 feet wide extending down the row will provide a good substrate for surface feeder roots. Mulch also moderates soil temperatures, aids in weed control, provides protection from mechanical injury, and adds organic matter to the soil. Weed control is extremely important for young plant establishment because blueberries are shallow-rooted plants that compete poorly with weeds for water and nutrients.
Blueberries should be pruned at the time of planting. If plants have a well-developed root system and irrigation is used, pruning should not be severe. Select the tallest, strongest cane and leave it unpruned. Remove the weak, “twiggy” growth at the base of the plant. If the plant has a large top compared with the root system, remove about one-third of the top by selectively pruning the least vigorous growth and cutting back the tops of vigorous canes by several inches. During the first growing season, remove all flowers before fruit set occurs. This will prevent fruiting during the first year and promote strong vegetative growth and good plant establishment. This is especially important with some southern highbush cultivars that flower heavily as young plants.
Aside from site selection, choosing the proper blueberry cultivars may be the most important decision a dooryard blueberry grower can make. Most blueberry cultivars grown in Florida are self-unfruitful; they require cross-pollination from another cultivar of the same type (southern highbush with southern highbush and rabbiteye with rabbiteye). Another requirement for good fruit set is that pollen vectors (usually bees) are present and working the flowers during bloom. With good pollination, berry yields of 2–5 pounds per plant may be expected by the third or fourth year. Some of the major blueberry cultivars commonly grown in Florida are described below.
Southern Highbush Cultivars. Southern highbush blueberries grown in peninsular Florida are the earliest blueberries to ripen in North America. These cultivars are generally considered more difficult to grow than rabbiteye types. Very early flowering makes southern highbush cultivars quite susceptible to late winter/early spring freezes and therefore not suited for extreme north and northwest Florida. Moreover, southern highbush blueberries are less forgiving of soil requirements and are generally more susceptible to some diseases such as Phytophthora root rot. However, in central or south Florida, southern highbush cultivars are preferred over rabbiteyes. The following is a list of the more common southern highbush cultivars available in Florida. All of the southern highbush cultivars described below are patented releases from the University of Florida breeding program. For a current listing of nurseries licensed to propagate and sell each of these cultivars, contact the Florida Foundation Seed Producers at (352) 392-9446 or look online at http://ffsp.net.
‘Emerald’ (Figure 1) was released by the University of Florida in 1999 and is currently one of the more widely planted cultivars in north and central Florida. It appears to be adapted from Gainesville to Sebring. ‘Emerald’ combines a vigorous, spreading bush with high yield potential, early ripening, and large, high-quality berries. ‘Emerald’ flowers open uniformly, and it produces abundant leaves even after mild winters in Gainesville. Because the plant is highly vigorous when planted on suitable soils, ‘Emerald’ is capable of carrying heavy crops. ‘Emerald’ normally reaches full bloom in Gainesville around February 15, thus flowers and fruit require protection from freezes in February and March. In Gainesville, first harvest occurs a few days earlier for ‘Emerald’ than for ‘Sharpblue’ and ‘Star’. About 80% of the fruit of ‘Emerald’ is normally ripe between April 15 and May 10 in Gainesville.
James W. Olmstead, UF/IFAS
‘Jewel’ (Figure 2) was released by the University of Florida breeding program in 1999 and has a moderately low chilling requirement, very early ripening, and high berry quality. ‘Jewel’ appears to be adapted to the region of Florida from Gainesville to Sebring. In Gainesville, ‘Jewel’ typically flowers about a week before ‘Star’ and ripens at approximately the same time as ‘Star’. The average harvest date of ‘Jewel’ in Gainesville is April 12, and harvest is normally finished by May 10. ‘Jewel’ produces a large number of flower buds but leafs well in the spring. Its vigor is high, which allows it to carry a large crop of high-quality berries. Its berry quality is excellent but tends to be tart until fully ripe. Its berry size is medium to large, its firmness is good to excellent, and its stem scars are dry and considered to be excellent. ‘Jewel’ is moderately susceptible to Phytophthora root rot and highly susceptible to rust leaf spot disease, which may require fungicide sprays to prevent early fall defoliation.
James W. Olmstead, UF/IFAS
‘Star’ (Figure 3) was released by the University of Florida in 1995. ‘Star’ has medium vigor but its survival in the field has been good. ‘Star’ has a higher chilling requirement than ‘Emerald’ or ‘Jewel’ and appears to be best adapted to north Florida and southeast Georgia. ‘Star’ has not performed well south of Ocala where it shows symptoms of inadequate winter chilling, including few flowers and weak vegetative growth. The average date for ‘Star’ to reach 50% bloom in Alachua County is February 23. The first half of the crop is normally ripe by April 26. ‘Star’ leafs out well in Gainesville and southeastern Georgia. ‘Star’ has a very short bloom to ripe interval and has a relatively compressed harvest period of about 3 weeks. Its berries are excellent in size and firmness, and its stem scar is minimal.
Jeffrey G. Williamson, UF/IFAS
‘Windsor’ (Figure 4) was released from the University of Florida breeding program in 2001 and is vigorous, with stout stems and a semi-spreading growth habit. ‘Windsor’ appears to be best adapted to north-central Florida but has been grown successfully as far south as Hardee County. The average date of 50% bloom in Alachua County is February 21, usually several days after ‘Emerald’ and about 3 days before ‘Star’. ‘Windsor’ leafs out strongly as it begins to flower, and this strong vegetative growth enables it to support a large crop. In Alachua County, fruit usually begin to ripen in early to mid-April, and 50% of the berries are normally ripe by April 24. ‘Windsor’ berries are very large. Berries from the first half of the harvest average about 2.4 grams on young vigorous plants. The berries are about the same color as those of ‘Star’. It has good firmness and excellent flavor. ‘Windsor’ has a deep picking scar, which complicates packing and reduces commercial postharvest life, but this is generally not a problem for home gardeners.
Jeffrey G. Williamson, UF/IFAS
‘Springhigh’ (Figure 5) is a vigorous, upright cultivar that has exceptionally good survival in the field. ‘Springhigh’ appears to be adapted to north-central and central Florida. ‘Springhigh’ ripens about 5–10 days earlier than the standard mid-season cultivars (‘Star’, ‘Windsor’, ‘Emerald’, and ‘Jewel’). The berries are very large and have good to excellent flavor. Berries of ‘Springhigh’ have less waxy bloom on their surfaces, making them darker than most other cultivars. They have only medium-good scars with a tendency for some tearing of the berry skin around the picking scar during harvest. Also, they have only medium firmness, which sometimes presents problems during commercial packing and shipping, but should not be an issue for home gardeners. The berries are very attractive to flower thrips, which in many years are abundant during the weeks when ‘Springhigh’ is ripening. If thrips populations are not kept very low when ‘Springhigh’ is beginning to ripen, their damage will soften the berries and reduce berry postharvest storage life.
James W. Olmstead, UF/IFAS
‘Sweetcrisp’ (Figure 6) is a vigorous plant with good field survival and a spreading growth habit. It flowers about the same time as ‘Jewel’ (which is later than ‘Emerald’ and earlier than ‘Star’ or ‘Windsor’) and ripens at about the same time as ‘Jewel’ and ‘Emerald’. The berry is sweet with a crisp crunch at the first bite. It is very firm and has exceptional postharvest life. The berries are smaller than those of ‘Emerald’, ‘Star’, and ‘Windsor’, and are variable in size, depending on the diameter of the twigs bearing the flowers. Flower bud number and berry yield in Gainesville are below average (less than most other cultivars), and it appears to be best adapted to north Florida and south Georgia. Because of its exceptional berry quality and postharvest storage, ‘Sweetcrisp’ has high potential for a garden cultivar in north Florida.
James W. Olstead, UF/IFAS
‘Farthing’ (Figure 7) is a vigorous plant with a dense, compact canopy. The leaves tend to be healthy and relatively free of leaf spot diseases. The berries are large and firm, and they have a good picking scar but tend to be dark in color because of low surface wax content. ‘Farthing’ produces numerous flower buds, and dormant pruning may be required to prevent over-fruiting. ‘Farthing’ flowers later than most Florida cultivars, but before ‘Star’ or ‘Windsor’. The berries on ‘Farthing’ generally ripen at about the same time as ‘Star’, but it produces significantly higher yields than ‘Star’. ‘Farthing’ has performed well in north-central Florida, but it is a new cultivar and its adaptive range has not been fully determined.
Jeffrey G. Williamson, UF/IFAS
Rabbiteye cultivars. Rabbiteye cultivars, as a group, are easier to grow than southern highbush. They are more tolerant to drought and less susceptible to Phytophthora root rot. They flower later in the spring, making them less susceptible to late winter/early spring freezes. They require less organic matter and less mulching, and they are generally more vigorous. Rabbiteye fruit has a slightly tougher skin and slightly larger seed than southern highbush fruit. Fruit from rabbiteye cultivars usually stores better than southern highbush fruit. Rabbiteyes require cross-pollination from another rabbiteye cultivar. The harvest season for rabbiteye blueberries extends from May to July, depending on the cultivar. Rabbiteyes are best adapted to areas of Florida north of Ocala.
‘Beckyblue’, ‘Bonita’, and ‘Climax’ are three early-season rabbiteye cultivars that are widely grown in Florida. These cultivars usually ripen in late May and early June in Gainesville. Early-season rabbiteyes have not been as productive under Florida conditions as the mid- to late-season cultivars. However, they are useful in extending the rabbiteye harvest season. For best pollination, plant ‘Climax’ with either ‘Beckyblue’ or ‘Bonita’. ‘Austin’ is a newer early-season rabbiteye cultivar that appears to grow well where ‘Climax’ is adapted and should cross-pollinate with other early-season rabbiteye cultivars.
Most of the mid- to late-season rabbiteye cultivars are more productive than the early-season rabbiteyes discussed above and are therefore better suited for home gardeners. ‘Brightwell’, ‘Powderblue’, ‘Tifblue’, and ‘Woodard’ have performed very well in north Florida and in the panhandle. These cultivars bloom later than the early-season rabbiteyes, and the flowers and young fruit are much less susceptible to late winter freezes. Other mid- to late-season rabbiteyes that can be grown in Florida but are less popular and may be harder to locate include ‘Chaucer’ and ‘Bluegem’.
Blueberries respond best to frequent, light fertilization. They can be killed or damaged by over-fertilization. It is best to be conservative and gradually increase fertilizer rates as you gain experience with your soil type and the kinds of fertilizer you are using.
Do not put fertilizer in the planting hole. After planting, when the soil is well settled from irrigation or rainfall, give un-mulched plants 1 ounce per plant of 12-4-8 (N-P2O5-K2O) with 2% magnesium (Mg). Use ammoniacal nitrogen or nitrogen from urea or organic sources, rather than from nitrate sources. Chlorine levels should be as low as possible, preferably below 2%. A special formulation called “blueberry special” is available in Florida and meets these requirements. Another possibility is “camellia-azalea” fertilizers. Many of these fertilizers are suitable for blueberries, and they are usually readily available in small quantities for home gardeners. Spread fertilizer evenly over a circle 2 feet in diameter with the plant in the center. Repeat this procedure in April, June, August, and October. If plants are heavily mulched, use 1.5 ounces per plant per application rather than 1 ounce because some of the fertilizer will be unavailable for plant uptake. During the second year, use 2 ounces of 12-4-8 per plant per application and spread it evenly over a 3-foot diameter circle. In the third year and beyond, use 3 ounces of fertilizer per plant per application spread evenly over a 4-foot diameter circle, or broadcast in a continuous band 3–4 feet wide, centered on the plant row. These are general guidelines and should be adjusted based on plant performance. Slightly more fertilizer may be required if plants are heavily mulched. However, more often than not, cultivated blueberries suffer more from over-fertilization than from lack of fertilization.
Mature blueberry plants need about 40 inches of water annually. Most of this water is provided by rain. Water requirements for blueberry plants are low during the winter. During most years, the combination of rainfall and water stored in the soil should limit the need for irrigation on moist soils between December 1 and March 1. The most critical period for irrigation of blueberry plants in Florida is from early fruit set until the end of harvest. For most cultivars, this corresponds with a period of high water use by the plants but low rainfall, meaning best results will be achieved with supplemental irrigation. During March, mature blueberry plants will require about 0.6 inches of water per week (rainfall plus irrigation). As leaf canopies continue to develop, and air and soil temperatures continue to increase, 1.0–1.2 inches of water per week (rainfall plus irrigation) will be needed throughout the late spring and summer months. The frequency of irrigation depends on the weather, soil type, and type of blueberry (rabbiteye or southern highbush). Established rabbiteye blueberries in gardens will require irrigation only during prolonged dry periods. They are as drought tolerant as evergreen azaleas. Southern highbush blueberries planted on very sandy soils may require three or more irrigations per week during dry periods. Most water from deep wells has a pH of over 7.0 and can increase the pH of sandy soils rapidly. If you suspect you have high-pH water, test your soil annually to monitor changes in soil pH.
If blueberry plants are not pruned, they eventually become dense, twiggy, and nonproductive. Pruning mature blueberry plants is largely a matter of cane removal or cane thinning and reducing the height of the canopy. The objective of pruning mature bushes is to stimulate the proper balance between vegetative and reproductive growth. Cane removal pruning stimulates the development of new canes, which tend to be more productive than older canes. Once the plant is four to five years old or older, a general rule is to remove about 1/4–1/5 of the oldest canes each year (usually 1–3 of the oldest canes). This will result in continuous cane renewal so that no cane is more than three or four years old. Mature plants are usually topped by removing several inches to a foot or more from the top of the canopy immediately after fruit harvest. This stimulates new growth that will produce next year’s crop and prevents plants from becoming too tall. Dormant pruning (December – January) to reduce the number of flower buds may also be required on some southern highbush cultivars such as ‘Farthing’ that set heavy crops. Flowers should always be removed from one-year-old plants by rubbing them off before fruit set occurs. Most pruning is usually done immediately after harvest during the early summer. Removal of some of the flower buds to adjust the crop load is usually done during the late winter just before growth begins.
Weeds compete with blueberry plants for water, nutrients, and sunlight. Maintaining several inches of acid-forming mulch (such as pine bark, pine straw, or oak leaves) helps control weeds and acidifies the soil in the blueberry plant’s root zone. Woven nursery fabric ground cover or plastic ground cover may be used as synthetic mulches but will not add to the soil organic matter. Be aware that these ground covers may reduce the availability of water from rainfall and the availability of nutrients from surface-applied fertilizers, and they may complicate irrigation and fertilizer practices. In any case, no weeds should be allowed to grow within two feet of blueberry plants.
Pests and Diseases
Many insects, diseases, and vertebrate pests can attack blueberries in commercial fields. Some can cause serious reductions in growth and yield, or can even cause plant death. However, most are sporadic in occurrence and normally cause little damage in small plantings. The most serious pests and diseases that have been observed on blueberries in Florida are discussed below.
Phytophthora root rot, caused by the fungus, Phytophthora cinnamomi, is responsible for the death of many plants in Florida, especially where soil drainage is poor to marginal. Root rot may result in sudden plant death, usually during the summer rainy season, or it may manifest itself as a slow progressive disease characterized by weak growth and early fall color development (yellow, orange, or red foliage) before adjacent healthy plants. Infested plants are often poorly anchored in the soil and usually have very few healthy fibrous roots. Phytophthora root rot is favored by excess soil moisture and high soil temperatures. The best defense against this disease is having good soil drainage and avoiding excess irrigation. Chemical control is currently available, and some cultivars are less susceptible to Phytophthora root rot than others, but none are immune.
Botrytis flower blight (gray mold), caused by the fungus, Botrytis cinerea, can destroy large numbers of rabbiteye flowers when periods of rainy, cloudy weather occur during bloom. This disease can occur on southern highbush blueberries but is generally more severe on rabbiteye cultivars. Under conditions favorable for disease development, all parts of the flower are susceptible to infection. Flowers may even become infected before they open. Flowers and flower buds should be kept as dry as possible. Overhead irrigation should be avoided during bud swell and bloom. Protective fungicides are available for control of this disease.
Blueberry stem blight, caused by Botryospheria spp., has resulted in significant plant mortality of southern highbush blueberry plants in Florida. The causal fungi are usually present in orchards and blueberry fields and cause a number of different diseases on various host plants. Rabbiteyes are usually not seriously affected by this disease, but some southern highbush cultivars are extremely susceptible. Various plant stresses such as over-fruiting, poor leafing, drought, and nutritional deficiencies predispose blueberry plants to stem blight. The best defense against stem blight is good horticultural practices that minimize plant stress. There is no chemical control for blueberry stem blight. The best methods of control available are pruning out infected wood, removing flower buds and fruit from young plants, pruning mature bushes to thin crop loads, and minimizing drought and other plant stresses.
Several insect pests damage blueberries in Florida, but, as with diseases, chemical treatments are usually applied only where serious damage is being inflicted. Some insects that can occasionally cause serious damage include flea beetles, various scale insects, cranberry fruitworms, caterpillars, root weevils, thrips, and blueberry gall midge. Spotted wing drosophila, a new pest in Florida, lays its eggs in blueberries and other fruit, and the resulting larval infestation can cause serious damage to the crop (for more information, see http://edis.ifas.ufl.edu/in839). Birds are the most serious vertebrate pest of blueberries, although the severity of their damage varies greatly from year to year. Cedar waxwings, robins, and crows have all caused economic damage at some locations in Florida during some years. Small blueberry plantings in the dooryard provide both food and cover for many attractive songbirds. Many homeowners welcome the bird life that blueberry plants attract to their yards, but few blueberries may be harvested from these garden plants unless they are protected by nets.
More information on blueberry pest and disease management can be found at http://edis.ifas.ufl.edu/topic_blueberry_ipm.
Blueberries can be grown successfully for the home garden in Florida. Rabbiteye, southern highbush, or both may be used depending on geographic location, site characteristics, and anticipated harvest season. Generally, rabbiteyes are the best choice for areas north of Lake City and southern highbush blueberries are usually preferred for areas south of Ocala. Only the low-chill cultivars that have been specifically bred for mild climates are suitable for Florida. Proper site and cultivar selection are probably the two most critical decisions for the blueberry gardener. Plants located too close to hardwood trees produce few fruit, although blueberry plants and pine trees are surprisingly compatible. Rabbiteye requires cross-pollination, and southern highbush benefits from cross-pollination. Cultivars of each type (rabbiteye with rabbiteye and southern highbush with southern highbush) should be mixed together, and natural bee populations should be encouraged for good pollination and fruit set. Growing several cultivars will also lengthen the harvest season. Major yield reductions occur from spring freezes and birds. Blueberry stem blight and Phytophthora root rot are major causes of plant mortality in Florida.
This document is Circular 1192, one of a series of the Horticultural Sciences Department, UF/IFAS Extension. Publication date: April 2004. Reviewed June 2015. Revised January 2012 and July 2018. Please visit the EDIS website at http://edis.ifas.ufl.edu.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.
U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.
I have several blueberry plants that didn’t blossom or fruit. I sprinkled aluminum sulfate and ammonium sulfate on them. Now the leaves are falling off and they seem to be going dead. Did I burn them? Will they come back?
There are two basic types of blueberries – highbush and lowbush. Highbush are the cultivated blueberries that grow best in a line extending from Muskegon to the lower end of the Saginaw Bay. Lowbush are the wild blueberries that grow throughout the state and are about 20 inches tall. Blueberries are considered to be a long-term crop as it takes between 8 and 12 years for them to reach maturity. With proper care, they can live for 20 to 40 years. I wonder how old your plants are and if they have ever produced flowers or fruit? Blueberries have fairly specific soil and climatic requirements for good production. Let’s go through these requirements and see if we can solve the mystery of no flowers and no fruit.
First, blueberries must have acidic soil with a pH below 5.5 and do best in soil with a pH between 4.5 and 5. Your soil should be tested before planting and regularly thereafter. If your soil pH rises above 5.1, add elemental sulfur or aluminum sulfate. Several pounds of sulfur or aluminum sulfate are needed per 1,000 square feet to lower the pH one unit. Ideally, your soil should have good drainage with a water table 14 to 22 inches below the surface. Blueberries need a consistent water source throughout the growing season but don’t like “wet feet.” When choosing plants, it is recommended that you choose a 3- or 4-year-old bare-root or container-grown plant, as younger plants have more difficulty getting established enough to maintain their winter viability and will take longer to bear fruit. Young plants are also fertilized differently than the older plants. Again, a soil test is preferable but in the absence of a soil test, these are the recommendations:
- Planting year – 2 to 4 weeks after planting, sprinkle 1 ounce of 20-0-10-5 (NPK magnesium) within 10 to 12 inches of the plant.
- Years 2-3 – Spread 2 ounces of 20-0-10-5 in a 2-foot diameter around the plant.
- Years 4-5 – Spread 3 ounces of 20-0-10-5 in a 3-foot diameter around the plant.
- Years 6-7 – Spread 4 ounces of 20-0-10-5 in a 4-foot diameter around the plant.
- Years 8-9 – Spread 5 ounces of 20-0-10-5 in a 4-foot diameter around the plant.
- 10th year to mature bush – Spread 3 ounces of 20-0-10-5 in a 4-foot diameter around the plant.
On an established planting, apply the fertilizer around the drip line of the plant. On sandy sites, you may want to use two applications of fertilizer: half before bud break and half at petal fall. This will help reduce leaching. If 20-0-10-5 fertilizer is not available, use urea or ammonium sulfate.
Blueberries are self-fruitful and will set fruit without cross-pollination but they do require “busy bees” for pollination and fruit set. Native bees will do the trick in the backyard garden. Regular pruning is necessary for a high yield production. The most fruitful canes are 4 to 6 years old and 1 to 1-1/2 inches in diameter. Bushes should have 15 to 20 percent young canes that are less than 1 inch in diameter, 15 to 20 percent old canes that are 2 inches in diameter and 50 to 70 percent canes that are of intermediate size. Prune the plants when they are dormant (fall to spring). In early spring, you have the advantage of being able to see the canes that were damaged during the winter. There are a number of diseases that can plague our Michigan blueberries and your local extension office can provide you very specific information on each of them.
Now back to your mystery… How old are your plants? Have they ever set flowers or fruited? If not, maybe they need more time. Blueberries are very susceptible to early fall and late spring frosts. What is your soil pH? You can contact your local extension about having a soil test done. Take a good look at the canes. What needs to be pruned? How is your drainage and do your plants get consistent water? Don’t give up! You will likely be rewarded by a little more detective work and patience.
Michigan State University Blueberry Facts
List of MSU Extensions
Tips on growing raspberries
Learn how to grow strawberries
Blueberry Plants Not Producing – Getting Blueberries To Bloom And Fruit
Do you have blueberry plants that are not producing fruit? Maybe even a blueberry bush that isn’t even flowering? Fear not, the following information will help you sleuth out common reasons for a blueberry bush that is not flowering, and about getting blueberries to bloom and fruit.
Help for Blueberries Not Fruiting
Blueberries, and their relatives, the cranberries, are the only native crops of North America that are commercially produced. There are two types of blueberry — the wild lowbush (Vaccinium augustifolium) and the cultivated highbush blueberry (Vaccinium corymbosum). The first hybrid blueberries were developed for cultivation in the early 1900’s.
There may be a number of reasons for no flowers on blueberries. While blueberries can grow in a number of soil conditions, they will only truly thrive in acidic soil with a pH below 5.5, ideally between 4.5 and 5. Test your soil to see if you need to amend it. If the soil pH is above a 5.1, incorporate elemental sulfur or aluminum sulfate.
Blueberries, like most plants, also need well-draining soil. Although they need consistent irrigation during the growing season, blueberries dislike “wet feet.” You should also plant them in full sun. A shaded area may prevent the plant from blossoming, hence setting fruit.
Additional Reasons for Blueberry Plants not Producing
While blueberries are self-fruitful, they will benefit from the close proximity of
another blueberry plant. If you have no flowers on your blueberries, you may have insufficient pollination.
Planting another blueberry within 100 feet (30 m.) of another will help bees cross pollinate the blossoms, boosting your chances for fruit production. In fact, planting a different variety nearby may result in larger as well as more plentiful berries.
If it seems that your blueberries are not fruiting, maybe you need to think again. Not only do we love fresh blueberries, but our bird friends do too. The blueberry may have fruited, but if you have not kept a close eye on it, the birds may have gotten to the fruit before you did.
The age of your blueberry may also result in low or non-existent production. First year blueberries should have their blossoms removed. Why? By doing so, you will allow the plant to put all of its energy into producing new foliage, which will lead to better fruit production the next year.
That said, one-year-old blueberries have a high mortality rate. It’s better to plant two- to three-year-old blueberries that are more established.
Older plants need to be pruned. Regular pruning is important to the health of blueberries and can affect fruit set. The most fruitful canes are not the largest. The most productive canes will be between four to eight years old and 1-1 ½ inch (2.5-3.75 cm.) across.
When you prune the plant, the goal is to have a plant that has 15-20 percent young canes less than an inch across, 15-20 percent older canes that are around 2 inches (5 cm.) in diameter and 50-70 percent in-between canes. Prune when the blueberry is dormant in the fall to spring.
Remove low growth around the base of the plant and any dead or weak canes. You should prune the plant in this manner each dormant season, removing about one-half to one-third of the wood.
Getting blueberries to bloom and fruit will probably also require some fertilization. Nitrogen for blueberries must be in the form of ammonium since nitrates are not taken up by blueberries. Don’t fertilize the first year the plant is set out since the roots are easily damaged.
Once the blueberry has flowered in the second year, apply 4 ounces of ammonium sulfate or 2 ounces of urea to the plant. Just sprinkle it in a ring around the plant; don’t work it into the soil.
For each year of growth, increase the amount of ammonium sulfate by one ounce or ½ ounce of urea up until the bush’s sixth year. Thereafter, use 8 ounces of ammonium sulfate or 4 ounces of urea per plant. A soil test will help determine if you need any supplemental NPK fertilizer.
Selecting Blueberry Varieties for the Home Garden
The blueberry bush makes a wonderful choice for the home gardener as a flavorful food crop or as an ornamental landscape shrub. There are several important considerations in deciding which particular varieties are best suited to the gardener’s goals, planting site, and climate.
Highbush blueberry has been commercially bred over the last 100 years and has developed a large number of diverse and productive varieties. Most home gardeners will select for taste, fruit size, and color in consuming berries fresh off the bush. Others may prefer smaller, firmer, and more flavorful fruit for baking, processing, or storage. Some gardeners are selecting landscaping varieties from a bush size and color standpoint to be utilized in specimen plantings, hedging, or accent pieces. Some varieties change their blue/green foliage to a striking orange, yellow, purple, or red color in the fall. Flower colors range from white to pink in a profuse springtime display.
Figure 1. Flower clusters on blueberry bush bloom for a one to two week period.
New Jersey encompasses three different plant growth zones; 6, 7, and 8. The cooler northern region 6 has a seasonal growing period of about 140 days from last spring frost to first fall frost, while the warmer southern region zone 8 has a much longer growing period of about 220 days. Low winter temperature in the north may range from -5° to 10°F compared to 10° to 20°F in the south. The central portion zone 7 is intermediate between these two growth zones. These climatic factors limit the culture of Rabbiteye (Vaccinium ashei) and southern highbush hybrid blueberry species. The lowbush blueberry species (Vaccinium angustifolium), native to New England and Canada, is also not very well adapted to our more moderate climate. The best selection is the highbush blueberry (Vaccinium corymbosum), our native species which is ideally suited to all three growth zones of the Garden State.
Highbush blueberry cultivars have an inherent resistance to many diseases of fruit, flower, and foliage. If the home gardener or small farmer is situated several miles away from large commercial blueberry production areas, insect pests will seldom cause significant damage. (See fact sheet FS106, “Blueberry Pest Management for the Homeowner”.)
Nonetheless, certain varieties have been selectively bred for resistance to common diseases in our area. These characteristics may be listed on the varietal label used by the commercial nursery.
There are also choices to be made in terms of transplant size and age. Bushes may be bare-rooted or pot-grown and one, two, or three years old. One year old plants are the least expensive but will not bear fruit for two years. The fruit buds need to be stripped off by hand in order to grow more foliage and deeper roots for a more productive harvest in the fourth year. Two year old plants are much more dependable in establishment and need only one more season of non-bearing. (See fact sheet FS750, “Establishing Blueberries in the Home Garden”.) Three year old plants are, of course, the largest and most expensive. This extra expense may make sense when only purchasing a few bushes for the home grounds in order to reach a faster harvest. Sources of certified virus and disease free blueberry plants can be found in commercial nursery catalogs, at home garden suppliers, accessed on the internet, or from your county extension offices.
Figure 2. A new variety, “Duke”, is noted for large fruit and high yield.
Late fall planting is preferred but a March timing is acceptable. This timing is less important when the plant is containerized, which suffers less from root disturbance and transplant shock. Purchase at least two varieties and plant them close together (3&en;4 feet) to increase cross-pollination. While most highbush blueberry varieties are self-fertile, all bushes benefit from exchanging pollen which increases fruit size, ripening, and yield. Another important consideration is the length of the harvest season which generally ranges from 2 to 6 weeks per cultivar. The gardener should select a mix of varieties having early, middle, and late season harvest times which can ripen in succession and cumulatively extend production periods (Chart 1).
While primary criteria for cultural choice by home gardeners are berry flavor, aroma, sweetness, and tartness; other considerations include berry size, berry color, cluster density, productivity, plant structure, bush size, vigor, and cold hardiness. Varietal information is compared in Table 1. If possible, visit your local “pick-your-own” blueberry farms several times during the season and sample all the varieties the growers have to offer.
|Variety||Season||Fruit Size||Color||Plant Type||Flavor|
|Earliblue||Very Early||Large||8||Upright/Spreading||Good||Firm, good aroma, good dessert quality|
|Bluetta||Very Early||Medium||5||Spreading||Mild||Soft, fair, short size|
|Ivanhoe||Early||Medium||7||Upright||Excellent||Firm aromatic, high dessert quality|
|Patriot||Early||Large||8||Upright||Very Good||Firm, aromatic, tasty, small bush|
|Stanley||Early||Medium||7||Upright||Very Good||Firm, aromatic, high dessert quality|
|Blueray||Late Early||Large||8||Spreading||Very Good||Aromatic, high dessert quality|
|Duke||Late Early||Large||8||Upright||Good||Firm, big bush, high yielder|
|Collins||Late Early||Large||8||Upright/Spreading||Good||Firm, good aroma, good dessert quality|
|Bluecrop||Mid Season||Large||9||Upright||Good||Firm, slightly aromatic, most popular|
|Berkeley||Mid Season||V Large||8||Spreading||Mild||Firm, good for storage|
|Concord||Mid Season||Small||6||Upright/Spreading||Excellent||Soft, slightly aromatic, good dessert quality|
|Pioneer||Mid Season||Medium||6||Spreading||Very Good||Firm, aromatic, high dessert quality|
|Atlantic||Late Mid||Large||7||Very Spreading||Very Good||Firm, slightly aromatic, medium dessert quality|
|Herbert||Late Mid||V Large||7||Very Spreading||Excellent||Soft aromatic, very high dessert quality|
|Legacy||Late Mid||Large||8||Upright/Spreading||Excellent||Firm, sweet, aromatic, stores well|
|Dixi||Late||Large||6||Very Spreading||Very Good||Firm, aromatic, high dessert quality|
|Elizabeth||Late||Large||8||Very Spreading||Excellent||Slightly acidic, aromatic, very high dessert quality|
|Darrow||Late||V Large||8||Upright||Excellen||Firm, slightly acidic, high dessert quality|
|Wareham||Late||Medium||6||Spreading||Excellent||Soft, aromatic, good dessert quality|
|Tophat||Late||Medium||7||Dwaft patio type||Fair||Firm, 2′ tall, no pollinator needed, baking|
|Coville||Late||Large||7||Very Spreading||Very Good||Firm, highly aromatic, tart, very high dessert quality|
|Bluegold||Late||Medium||8||Upright/Spreading||Excellent||Medium, firmness, productive, winter hardy|
|Jersey||Very Late||Medium||6||Upright||Good||Classic taste, stores well|
|Late Blue||Very Late||Small||8||Upright||Very Good||Firm, strong flavor|
|Elliott||Very Late||Medium||8||Upright||Mild||Firm, reddish wood, good dessert quality|
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This popular small fruit bears plenty of berries that are delightful when eaten fresh, used in pies, muffins, or pancakes, or added as a fruit topping for breakfast cereals. Also, blueberry plants add beauty to the landscape when grown in beds, rows or as a hedge along the property border. Blueberry-growing presents a challenge because the plants require soils that are acid, well-drained, loose and high in organic matter. These types of soils are not common in most areas of the state. However, blueberry plants can be very long-lived (25 years or more), so the considerable time and expense in preparing the soil is well worth the effort.
‘Premier’ Rabbiteye blueberries (Vaccinium virgatum) ripening in late June.
Joey Williamson, ©2015 HGIC, Clemson Extension
There are three main types of cultivated blueberries that can be grown in the Southeast: rabbiteye, Southern highbush and Northern highbush. This fact sheet focuses on the rabbiteye and Southern highbush types, as they are more adapted to the South Carolina climate and soils.
In general, rabbiteye blueberries (Vaccinium virgatum) are the most adaptable, productive and pest-tolerant of the three types of blueberries. Except for higher mountain elevations, rabbiteye cultivars are adapted to all of South Carolina. In general, rabbiteye blueberries have a great degree of self-incompatibility; therefore, a minimum of two varieties is required for adequate cross-pollination to ensure maximum fruit.
Chilling hours are listed for many cultivars, and this requirement means that the blueberry plants need to be exposed to a sufficient number of hours of winter temperatures below 45 °F in order to produce flowers. The chilling hours in SC range between 1000 to 1200 hours in the upper Piedmont to as low as 400 to 600 hours near the coast.
Southeastern U.S. Region map showing approximate minimum number of chilling hours by state/region. Note: four chilling hour zones for South Carolina with yellow arrows.
The following rabbiteye cultivars are recommended in South Carolina.
Early season cultivars:
- Climax: Plants require 450 chilling hours. This cultivar has a concentrated fruit set with small to medium sized fruit. Recommended cross pollination with Premier or Austin.
- Krewer™: PP 28623. Requires 400 to 450 chilling hours. Fruit are very large and have a very favorable firmness and sweet flavor. It is a companion to Titan and suitable for commercial growing, pick your own operations, and home gardens.
- Vernon: PP19291. Requires 450 hours of chilling. Flowers 7 days after Climax, but ripens before Climax and Premier. Fruit are large, firmness is excellent, and have good flavor and color. Recommended cross pollination with Alapaha.
- Alapaha: PP16266. Requires 450 to 500 chilling hours. This cultivar has a medium size fruit with good firmness and flavor. Flowers 7 to 10 days after Climax, which helps avoid spring freeze damage to flowers. Recommended cross pollination with Vernon.
- Austin: Plants require 500 chilling hours. Plants are productive and produce medium-large berries. Recommended cross pollination with Climax or Premier.
- Titan™: PP24135. Requires 500 to 550 hours of chilling. Fruit are very large – larger than Vernon or Premier. Flavor and color are good, but fruit may crack under wet conditions during ripening. Recommended cross pollination with Vernon and Krewer.
- Premier: Requires 550 chilling hours. Plants produce medium to large sized fruit. Recommended cross pollination with Austin or Alapaha.
- Brightwell: Requires 400 chilling hours. Fruits are medium to large size, but may split during wet weather. Recommended cross pollination with Austin or Premier.
- Powderblue: Plants require 600 chilling hours. Plants have good production of medium sized, light blue fruit. Recommended cross pollination with Tifblue or Brightwell.
- Tifblue: Requires 650 chilling hours. Plants produce small to medium size fruit, which must get fully ripe or they will be tart.
Late season cultivars:
- Baldwin: This late maturing cultivar requires 450 to 500 chilling hours. The plants have moderate yield and high vigor. The fruit are large, of good quality and very dark blue color. Cross pollinate with Brightwell, Powderblue, and Centurian.
- Centurian: Centurian plants need 550 to 600 chilling hours for fruiting. The fruit are very good quality, medium-sized, firm, and darkish-blue. The fruit may crack with heavy rainfall. Pollinate with Brightwell, Ochlockonee, and Powderblue.
- Ochlockonee: PP17300. Requires 650 to 700 chilling hours. This cultivar is very productive with fruit larger than Tifblue. Fruit has good color, firmness and flavor. Recommended cross pollination with Powderblue.
- Onslow: This cultivar has fruit slightly larger and darker than Powderblue. For fruiting the plants require 500 to 600 chilling hours. The plants are productive and vigorous. It has been reported that Onslow may tolerate soils of a higher pH than other cultivars. The fruit are large, with very good firmness and a medium blue color.
Southern highbush blueberries are hybrids derived from crosses between Northern highbush blueberries (V. corymbosum) and native Southern species, mainly Darrow’s evergreen blueberry (V. darrowi). Southern highbush cultivars, in addition to lower chilling requirements, also have greater tolerance to high summer temperatures, somewhat greater drought tolerance and develop superior fruit quality under Southern growing conditions. Mulch plants with pine straw to conserve soil moisture, but do not over-water Southern highbush plants if grown in heavy, poorly drained clay soils.
As a rule, Southern highbush blueberries are self-fertile. However, larger and earlier-ripening berries result if several cultivars are interplanted for cross-pollination. The following Southern highbush blueberries are recommended for the home garden.
Early season cultivars:
- Georgia Dawn™: PP16756. Plants require 300 to 400 chilling hours. Fruit are medium to large size with a medium dark blue color. Fruit have acceptable firmness with outstanding flavor. Plants are vigorous growers and very early ripening. Recommended cross pollination with Rebel.
- Palmetto: PP17656. Chilling requirement is 350 to 450 hours. Fruit are medium sized with a medium dark blue color with acceptable firmness. Plants are very productive and have good vigor. Recommended cross pollination with Suziblue.
- Rebel: PP18138. Plants require 400 to 450 chilling hours. The fruit are large with good to excellent color and firmness. Fruit can become bland if they remain on the plant too long. Plants are productive. Recommended cross pollination with Suziblue.
- Southern Slendour: PP22692. Fruit are medium to medium-large, very firm and with outstanding flavor. Plants produce a medium yield. The chilling requirement is 450 to 550 hours. Recommended cross pollination with Suziblue.
- Blue Suede™: PP21222. Plants are productive with attractive light blue fruit. Fruit are large and flavorful. The chilling requirement is 500 to 550 hours. Recommended cross pollination with Camellia or Palmetto. The fall foliage has a deep red color.
- Summer Sunset™: PP applied for. Chilling requirement is 500 to 550 hours. Fruit are medium sized and multi-colored as they go through the stages of ripening (first yellow-green, then orange-red, to red, to purple, and finally black). The plant is vigorous. Recommended cross pollination with Titan.
- Suziblue: PP21167. The chilling requirement is 400 hours or less. This cultivar has fruit that are large, with very good firmness, and good flavor. Plants are vigorous. Recommended cross pollination with Rebel.
- Camellia: PP18151. The chilling requirement is 500 hours. The fruit are large, firm and flavorful. The plants are vigorous growers. Recommended cross pollination with Suziblue.
Dwarf blueberry plants for containers: These smaller cultivars are all hybrids and are self-pollinating. However, self-pollinating cultivars will produce both a larger quantity of fruit, and the berries will typically be of a larger size if they are cross-pollinated by another cultivar. The dwarf cultivars listed below are recommended for South Carolina because of their heat tolerance and low chilling requirement for fruiting. Place containers in full sunlight for best flowering and fruit production.
- ‘Blueberry Sunshine’: Fruiting requires 150 chilling hours, and plants grow well in USDA zones 5 to 10. Flowers are white to pink. Fruits ripen mid- to late season, and berries are medium sized. Foliage turns burgundy in fall. Plants grow to 3 to 4 feet tall and wide.
- Peach Sorbet®: PP23,325. This dwarf cultivar has white flowers and emerald green leaves with new foliage in shades of pink and orange. It grows well in USDA zones 5 to 10 and is semi-evergreen. These compact plants grow to 1½ to 2 feet tall and wide.
- Pink Icing™: PP23,336. This cultivar has pink flowers and grows to 3 to 4 feet tall and wide. It grows well in USDA zones 5 to 10, and its fruit ripen in mid-season.
- Blueberry Glaze®: PP25467. This is a dwarf cultivar that requires a bit more chilling hours than the others (500 to 600 hours below 45 degrees). Plants grow to 2 to 3 feet tall and wide and grow well in USDA zones 5 to 8. The fruit are small black berries with intense flavor and ripen mid-season.
Plant Growth Cycle & Yields
Two-year-old bare-root nursery plants 1 to 3 feet tall are transplanted in late winter or early spring. Potted plants can be transplanted in the fall. Growth begins with bud swell in the spring and continues into late summer and fall. The blueberry produces several flushes of rapid shoot growth. Each growth flush ceases when the uppermost or apical bud aborts (this is not a disease). Soon after, a bud “breaks” near the tip to begin another flush of shoot growth. Each shoot may experience several of these growth flushes during the season, and each flush may result in 6 to 10 inches of growth with adequate moisture and nutrition. Shoot growth usually stops in midsummer.
Typically, five to eight flower buds can develop on a healthy shoot. Each flower bud can produce from five to 10 flowers that continue to develop inside the bud throughout the fall and early winter months. Both vegetative and flower buds become dormant in winter. Flower buds open sequentially in the spring, with the flower buds on the tip of the cane opening first. The flowers inside a bud open up in a similar sequence with the flower nearest the tip opening first. Shoot thickness affects blooming sequence, with blossoms on thinner wood opening up earlier than buds on thicker wood.
It is best to remove all flower buds in both the first and second years after planting to stimulate good shoot and root development. Blueberry flowers and fruits sap considerable energy from the plant, and fruit yields in subsequent years can suffer because of poor plant development in the first two years of establishment. In addition to removal of the flower buds, head-back the top one-third to one-half of all shoot growth on rabbiteyes at the time of transplanting.
Blueberry fruit ripens over a two-month period after bloom. This will vary with the cultivar, weather conditions and plant vigor. Plants should produce about a half-pound per bush in the third year, and 1 to 2 pounds per bush in the fourth year. With good care, mature Southern highbush plants can produce more than 8 pounds of fruit each year. Rabbiteye can produce 12 to 25 pounds.
Soil pH Adjustment: Have a soil test taken in the fall before planting in late winter or early spring. If the pH is above 6.0, select another planting site. If the soil pH is below 6.0 but above the 5.5 limit, apply wettable sulfur (90 percent sulfur). A very low soil pH caused by excess sulfur can be detrimental. Some soils in the Piedmont are very high in manganese. When growing blueberries on these soils, keep the pH above 5.0 to avoid problems with manganese toxicity. Any sulfur applications should be made at least three months prior to planting because it takes several months for sulfur to reduce the pH. Check the pH once or twice during the first growing season to determine if still more sulfur is required later in the season.
Sometimes, the impatient home gardener will insist on planting without a soil test. In this case, mix 1 cubic foot of peat moss with an equal amount of sand. It is important to use a sand that has not been limed or that does not contain a liming material. Most builder’s sand, referred to as “sharp” sand, does not contain liming materials.
Soil Water Drainage: On a heavy clay soil or a soil that sometimes remains wet, apply the peat-sand mixture to the soil surface and plant. If the soil has good drainage, part of the peat-sand mixture can go in a hole or furrow several inches below the soil surface. However, leave enough of the peat-sand mixture to form a mound (for single plants) or a ridge (for a row of plants) at least 6 inches above the surrounding soil surface. The mound or ridge will protect plants from excess water; however, with this method of planting, water thoroughly two to three times per week during dry spells in the summer and early fall. Logs, landscape timbers, stones, bricks or concrete blocks can be used to contain the soil mixture in the raised bed.
Preplant Additions of Organic Matter: Blueberries are naturally adapted to high organic matter soils where soils have 3 percent or more organic matter as opposed to most mineral soils with organic contents usually less than 1 percent. Organic materials such as peat moss, composted pine bark or rotted softwood sawdust should be incorporated in soils of less than 2 percent organic matter prior to planting to greatly improve blueberry plant survival and growth. Hardwood sawdust is not as effective as softwood sawdust or peat moss for lowering soil pH. Undecomposed softwood sawdust should not be used.
Follow this popular step-by-step pre-plant program to modify soils with less than 2 percent organic matter:
- Establish the plant mounds or ridges (3 feet wide) to provide the required drainage on poorly drained soils;
- Apply 4 to 6 inches of organic matter over the row in a band 18 to 24 inches wide and incorporate thoroughly using a rototiller or spade to a depth of 6 to 8 inches;
Steps 1 and 2 should be completed in the fall prior to planting in late February to late March, depending on location. If the organic matter is incorporated in the fall, any sulfur required to lower the pH can be added at the same time.
Note: Water and nutrient management is difficult in pure organic material, and the plants are more likely to struggle and die.
Plants: Two- or 3-year-old nursery plants 1 to 3 feet tall will transplant well. Keep the roots moist at all times between digging and replanting.
Time: Late winter (February-March) as soon as the soil can be worked is best for bare-root plants; fall (November-December) planting has been successful on sandy soils with bare-root plants and in other areas with potted plants.
Spacing: Southern highbush – 4 to 5 feet in the row and 8 to 10 feet between rows. Rabbiteye – 6 feet in the row and 10 to 12 feet between rows.
Depth: Plant to the same depth that the plants were growing in the nursery or the container. Lightly firm the soil around the plant with your feet and water thoroughly.
Cut Back: Remove all shoot tips that have flower buds (plump rounded buds). Avoid making cuts near the base of the plants that will provide an entryway for stem blight disease. To enhance survival and subsequent growth and development, prune away two-thirds of the top growth on bare-root and one-half on potted plants. Leave only one to three of the most vigorous upright shoots and any other growth near soil level.
Surface Mulch Application: Organic material such as bark, wood chips, sawdust or pine straw as a 2- to 3-inch mulch on the surface after planting results in more uniform soil moisture, moderates soil temperature and generally promotes better growth and survival. Pine bark chips or sawdust have a pH between 3.5 to 4.5 and are more desirable than the same mulches from hardwoods with a pH above 5.0. However, surface-applied hardwood mulches have been satisfactory. Avoid sticky hardwood sawdust that will “seal” the bed and prevent water infiltration.
Use Caution: Blueberries are easily damaged by excess fertilizer. Apply the recommended amount and allow 4 inches of rain or an equivalent amount of irrigation between applications.
First Year: Do not fertilize immediately after planting. Wait until the first leaves have reached full size, then apply 1 tablespoon of a special azalea fertilizer (such as a 10-5-4, 10-8-8 or 11-7-7) within a circle 12 inches away from each plant. Repeat at about six-week intervals depending upon rainfall or irrigation until mid-August in the Sandhills and Coastal Plain, and mid-July in the Piedmont. Use a half-tablespoon of ammonium sulfate instead of a complete fertilizer for the second and subsequent applications if high levels of phosphorus are present as determined by a soil test.
Second Year: Double the first year’s rates, but increase the circle around the plants to 18 inches. Make the first application when new growth begins in the spring.
Bearing Plants: When growth begins in the spring, apply 1 cup of a complete fertilizer, such as an Azalea fertilizer within a circle 3 feet from each plant. For more vigorous growth, sidedress with a quarter-cup of ammonium sulfate at six-week intervals, but stop fertilizing after July 1. On mature bushes, 6 to 12 inches of new growth is adequate. Any additional growth must be pruned away to keep the plants from becoming excessively large and resulting in a loss in production. Judge the sidedressing requirement on the amount of shoot growth and leaf color.
Lowering pH: If the soil pH is slightly high in an established planting based on soil test results, sidedress with ammonium sulfate, and apply iron sulfate if needed to correct the yellowing of foliage.
If mulch is applied following planting and replaced at the rate of 1 inch per year, few weed problems should develop. Pine straw is acidic and makes an excellent mulch. Handpull or hoe the occasional weed growth. Avoid deep cultivation since blueberry roots are very near the surface. Hoe no more than about 1 inch deep.
Since blueberries are produced from buds on 1-year-old wood, pruning should be severe enough to encourage the production of vigorous new growth each year. Because rabbiteye blueberries are vigorous and can support and develop heavy crops of large-sized fruit, they generally require less pruning than southern highbush blueberries. During the first five years little pruning will be required. Remove lower twiggy growth, dead or damaged shoots, and weak, spindly growth. Tip back excessively long and limber shoots to stimulate lateral branching and to thicken the shoots. Prune young plants during the dormant season and immediately after harvest with older plants.
If plants become too tall to harvest easily, selectively remove about one-third of the older canes in the winter. Generally up to seven canes are left each year after pruning mature rabbiteyes, with the oldest or largest cane removed each winter beginning in the fifth year. These selective cuts should be made to open up the center of the plant to improve light penetration and to allow new canes to develop to replace old canes.
Southern highbush blueberries require annual pruning to prevent overbearing and to maintain vigor. Prune during the dormant season; late winter is most desirable, especially in the mountains.
If the flower buds were removed after planting, little pruning will be required the second year except to remove all flower buds and any weak, damaged or diseased growth. After two growing seasons, leave some flower buds on vigorous shoots to produce a small crop in the third year. To prune bearing-age plants, remove low spreading branches and branches growing through the center of the bush, especially weak and older branches. Cut back extremely vigorous 1-year-old shoots and remove most small slender branches. If earliness is important, remember that berries produced on small slender laterals will usually be the first to ripen, so this should be taken into account in determining the number of these shoots to remove. Also, long-fruiting lateral shoots need to be tipped back so that no more than four to six flower buds remain.
Highbush blueberry plants generally reach their peak production between 8 and 10 years of age. To maintain bush vigor with the continued production of high-quality fruit, renewal pruning must be practiced. Begin the renewal process when the bushes are about 6 years old. First, remove any weak or diseased canes entirely. Among the remaining canes starting with the older ones, cut back about two per year either to strong lateral branches or to within 1 foot of the ground. New strong lateral branches will usually develop below the cut. Through renewal pruning, a new upright framework can be developed over a four- to five-year period.
Blueberries may be troubled by fungal leaf spots, fruit rots, root rot and gray mold. The primary insect problems are cranberry fruitworm (which ties berry clusters together with silk), Oberea stem borer (the larva bores down the stem resulting in stem death), Japanese beetles, and yellownecked caterpillars. The latter two insect pests feed on blueberry foliage.
The yellownecked caterpillars (Datana ministra) feed in groups and can quickly strip all of the foliage from blueberry stems.
Joey Williamson, ©2018 HGIC, Clemson Extension
Bird Protection: Birds also harvest blueberries, often the complete crop from a small planting. Plastic or cloth netting draped over the bushes or supported on a framework is the only practical control.
Frequency: Southern highbush blueberries have the best quality when picked every five to seven days depending on temperature. Rabbiteye flavor improves if berries are picked less often, about every 10 days, which allows for maximum flavor with few soft overripe fruit.
Taken from “Small Fruits in the Home Garden,” by E.B. Poling, North Carolina Master Gardener Manual, NC State University.
Important stages in the development of fruit and vegetative growth in blueberries: (A) dormant stage after leaf drop showing one flower bud; (B) blooming stage that shows the cluster of flowers and vegetative shoot that developed from the top two buds of the dormant stage; (C) fruit set stage where pollinated flowers begin developing into small fruits; (D) fruit development stage that extends from fruit set to mature fruit. Both flower and vegetative buds for the next season are often easily recognized on vegetative shoots at the time fruit ripens.
Blueberries: Origins – Consumption – Nutrition Facts – Health Benefits
- Geographic origin and regions grown
- History of consumption
- Common consumption today
- Nutrition Facts: Vitamins, minerals and phytochemical components
- Health Benefits: Medicinal uses based on scientific studies
Geographic Origins and Regions Grown
Blueberries are flowering plants from the genus Vaccinium. This plant species is native to North America, most of Asia, and Scandinavia. Blueberry shrubs grow in a variety of sizes that vary from a few inches to 10 feet. The plant also makes colored flowers which may be one of many colors like white, pale pink, red, and sometimes light green. The plant bares small blueberry fruits that have a dark purple color.
They have a sweet taste when ripe and the plants produce fruit once a year during the summer months. Vaccinium is the name for the entire blueberry family and includes hundreds of other related plants. Other names by which the blueberry is known include: cowberry, cranberry, farkleberry, lingonberry, partridgeberry, whortleberry, and sparkleberry.
North America is the number one producer of blueberries, with an astounding nearly 90 percent of world’s blueberries being grown in the US currently. Although the USA and Canada are the largest producers and consumers of blueberries, the market around the world is on the rise with Japan in particular becoming a blueberry loving nation.
History of Consumption
The blueberry has been consumed by the native North American Indians for hundreds of years. Surprisingly, the blueberry plant is associated with more folklore than most American fruits. Many years ago after the Europeans arrived in North America, they began to cultivate blueberry farms and took the blueberry plant back to Europe with them. Soon after that, blueberries became popular in many European countries and were no longer a popular fruit in just North America. Today the fruit is well recognized for its sweetness and is sold worldwide.
Besides the fruit, the berries are also crushed and the juice is extracted. The North American Indians have used blueberry juices for years to treat numerous medical ailments as well as a dying agent for their clothes. The dried berries were also crushed into a powder and rubbed into meat for flavor.
As the centuries progressed, blueberries became an important food source and were preserved, and later canned. In addition, a beverage made with blueberries was an important staple for soldiers during the Civil War. In the 1880s a blueberry canning industry began in the Northeast of the USA. The leaves and roots of blueberry plants were also used quite often in combination with the fruit for medicinal purposes.
Common Consumption Today
Delicious fresh blueberries are a summertime treat and tradition in North America. About 50 percent of all blueberries produced are dedicated to the fresh fruit market. Blueberry season takes place in the summer when the berry has a deep blue color. During this season the blueberries are carefully handpicked and immediately packaged. To preserve their flavor, they are chilled and rushed to markets in the nearby cities and shipped by air freight around the world.
Blueberries are usually sold fresh or first processed and then sold as frozen fruits, juice, purée or dried fruits. Regardless of the way blueberries are purchased, they are typically used in a variety of foods such as pies, jams, snacks, muffins and cereals.
Nutrition Facts: Vitamins, Minerals and Phytochemical Components
Blueberries have earned the reputation of a super fruit and evidence indicates that the fruit is rich in nutrients like fiber, vitamin K, vitamin C, iron, and large amounts of manganese. Blueberries also contain resveratrol, which is a phytoalexin that is produced by plants when they are experiencing a bacterial or fungal infection. Phytoalexins are antibacterial and anti-fungal chemicals that are produced by plants as a means of protection against pathogens.
In 1997, it was discovered that resveratrol also has anti-inflammatory properties (2). Recently resveratrol has been labeled as a nutraceutical because its chemical properties provide protection against chronic diseases (1). In addition to resveratrol, blueberries contain anthocyanins and polyphenol antioxidant pigments that have been shown to help reduce the risk of getting some diseases such as certain types of cancers (4).
Health Benefits: Medicinal Uses Based on Scientific Studies
Laboratory studies with blueberries have revealed that its phytochemicals like tannins, flavonols, anthocyanins and proanthocyanidins inhibit some of the ways by which cancer cells grow and develop (4). Blueberries have also been shown to diminish the signs of dementia and improve cognition in Alzheimer’s patients (3).
Other preliminary research has determined that blueberries can lower the amount of damage after a stroke (6). Blueberries also improve symptoms caused by urinary tract or bladder infections, improve skin tone and turgor, and lower cholesterol (5).
Current studies are being performed to determine which compounds in blueberries are most beneficial for heart disease. As of now, the blueberry can be simply enjoyed as a delicious fruit and all the other medical benefits are just a bonus.
1. Health Canada. (1998) Policy Paper on Nutraceuticals/Functional Foods and Health Claims on Foods. Health protection branch, 1-29.
5. Sumner, Judith (2004). American Household Botany: A History of Useful Plants, 1620-1900. Timber Press, 125.
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SEE ALSO: Blueberry Terminology & Names
The blueberry of the genus Vaccinium, is a native American species. In fact the blueberry is one of the few fruits native to North America.
Native American Tradition
For centuries, blueberries were gathered from the forests and the bogs by Native Americans and consumed fresh and also preserved. The Northeast Native American tribes revered blueberries and much folklore developed around them. The blossom end of each berry, the calyx, forms the shape of a perfect five-pointed star; the elders of the tribe would tell of how the Great Spirit sent “star berries” to relieve the children’s hunger during a famine.
Parts of the blueberry plant were also used as medicine. A tea made from the leaves of the plant was thought to be good for the blood. Blueberry juice was used to treat coughs. The juice also made an excellent dye for baskets and cloth. In food preparation, dried blueberries were added to stews, soups and meats. The dried berries were also crushed into a powder and rubbed into meat for flavor. Blueberries were also used for medicinal purposes along with the leaves and roots. A beef jerky called Sautauthig (pronounced saw’-taw-teeg), was made with dried blueberries and meat and was consumed year round.
During the seventeenth century, settlers from England arrived in the New World to begin colonies. Immediately, they set about clearing the land and establishing farms for they could not rely solely on supplies from England. But the land and the climate were far different from what they left behind. Many early attempts at farming failed.
In the winter of 1620, the Pilgrims established a settlement at Plimoth (spelled Plymouth today). Many perished during the first few months, but those that survived went on to build homes and establish farms. Their neighbors, the Wampanoag Indians taught the settlers new skills that helped them survive. They showed them how to plant corn and how to gather and use native plants to supplement their food supply. One important native crop was blueberries!! The colonists learned from Native Americans how to gather blueberries, dry them under the summer’s sun and store them for the winter.
In time, blueberries became an important food source and were preserved, and later canned. A beverage made with blueberries was an important staple for Civil War Soldiers. In the 1880s a blueberry canning industry began in the Northeast USA.
Vacinnium is the family of all blueberries and includes more than 450 plants. This plant grows wild around the world and there are many names given to different blueberries.
For practical and commercial purposes we concentrate on three different varieties:
Vacinnium corymbosum. (Northern Highbush) Grow in the forests wild in North America and were used to cultivate the modern highbush or cultivated blueberry industry along with the V. Ashei.
Vacinnium ashei. (Southern Rabbiteye). You may be suprised to learn that blueberries thrive in the Southern USA. A variety called the Rabbiteye is named this because the calyx on the berry resembles the eye of the rabbit!
Vacinnium angustifolium. (Lowbush or also called “Wild blueberries.” These dwarf bushes are very cold hardy, surviving in the wild as far north as Arctic North America. These Blueberries only reach a height of 1 or 2 feet. and include the low sweet Blueberry (V. angustifolium), which is found from the Arctic to Minnesota and the mountains of New York and New Hampshire, and the sour-tasting velvet-leaf Blueberry (V. myrtilloides), which is found wild throughout New England and west.
Many different names have been given to the numerous varieties of Vacinnium that produce edible fruits, such as Blueberry, Bilberry, Cowberry, Cranberry, Crowberry; Farkleberry, Lingonberry, Partridgeberry, Huckleberry (not the true Huckleberry, which is Gaylussacia), Whortleberry, and Sparkleberry to mention a few.
THE IMPROVED BLUEBERRY
For years, blueberries maintained popularity in the USA, with a thriving commercial business in the Northeast USA and Canada. An important step in the development of the highbush blueberry industry came in the turn of the century. Efforts in the early 1900’s by Elizabeth White and Dr. Frederick Coville to domesticate the wild highbush blueberry resulted in today’s cultivated highbush blueberry industry. They selected desirable plants from the wild forests of the Northeast USA and cultivated them to develop blueberries that could be commercially grown by farmers. Their initial breeding work has resulted in the plump, juicy, sweet and easy to pick cultivated blueberry we enjoy today. Without this cultivation work we would not have fresh blueberries in the markeplace as we do today.
Over the decades, plant breeders and pathologists have worked to identify and enhance the desirable features of various cultivars of highbush blueberries. For decades “cultivated” or “highbush” blueberries have been improved through natural selection and plant breeding programs to produce an optimal blueberry with desirable flavor, texture and color for fresh and processed markets. Cultivated varieties have been enhanced to offer magnificent plump berries with deep, rich color and a delicious fruity flavor. These plant breeding programs have resulted in the development of superior berries both for the consumer and the food processing industry. Our industry owes a great gratitude to the many agriculturalists in the USA and abroad who have pioneered the development of the US Highbush Blueberry industry!
The Modern Highbush Blueberry Industry
Today, the highbush blueberry is grown commercially in more than 38 states and provinces of Canada. Highbush blueberry industries have also developed in South America, Australia, New Zealand and Europe and according to the United Nations Food & Agricultural Organization, more than 42,000 metric tons are harvested each year. Although the USA and Canada are the largest producers and consumers of blueberries, the market around the world is also on the rise with Japan in particular becoming a blueberry loving nation.
Courtesy of the US Highbush Blueberry Council
Blueberries are a delicious summer treat. But wait, how did these blueberries get to your fridge?
To understand this, let’s understand the story of Elizabeth Coleman White—otherwise known as the “Blueberry Queen.”
Before White, blueberries were only a wild crop. Though there were many attempts to grow blueberries on a farm-like setting, all of these attempts were unsuccessful.
The first commercial blueberry harvest was in 1916—100 years ago. This harvest was on Whitesbog, a giant berry bog owned by J.J. White, called the “King of Cranberries.” His daughter was Elizabeth.
In 1910, Elizabeth found a USDA publication that struck her interest, which was titled “Experiments in Blueberry Culture.” She decided the write to the scientist behind this pamphlet, Dr. Fredrick Coville, writing:
“Dear Sir: I recently received from Washington, the report on ‘Experiments in Blueberry Culture,’ which I have read with great interest, and I write to make a suggestion in regard to future experiments. My father, Joseph J. White, is one of the largest cranberry growers in the country, and on his property are considerable areas of land too high for cranberries, but admirably suited to blueberries, judging by the way the wild ones flourish. Very respectfully yours, Miss Elizabeth C. White”
Dr. Coville was a botanist who had spent four years studying blueberries and writing almost 200 papers on blueberry cultivation. He decided to work with Elizabeth to cultivate blueberries, and they needed the help of an often-scorned group of people: the “pinies.” These were the poor and uneducated people who lived in the New Jersey woods. It wouldn’t be expected that a wealthy woman like Elizabeth or an esteemed scientist like Dr. Coville would interact with these people.
Elizabeth paid the pinies $1 for each blueberry bush they found, which was more than a day’s work worth of money. She had them mark the bluest and best berries, then Dr. Coville would breed the blueberries together. Their exchanges were central to this project.
Elizabeth later wrote that “they contributed one essential part, Coville contributed central part, my father and I contributed another essential part. Without the cooperation of all 3, this work would not have been possible.”
Consider that it took thousands of years to domesticate the apple, but less than a decade to domesticate the blueberry! This is one example of the blueberry coverage.
But the new developments would have been pointless without good marketing efforts, which Elizabeth mastered. She decided to wrap the new berries in cellophane, which she had seen as an appetizing technique used to sell chocolates. Blueberry fields across this area of the United States sprouted up, because she sold trimmings of blueberry bushes across the county. Blueberries were an immediate hit among growers, because they grew during a typical “off-season” and in acidic soil.
But this success was not without controversy. Child labor was an extremely controversial issue at this time, like debates about immigration of gun control nowadays. And Elizabeth was right in the center of this issue.
In 1913, Good Housekeeping published an inflammatory article titled “Who Picked Your Cranberries?” This article talked about the hardships that child laborers faced. This article said,
“In the state of new Jersey, between one thousand and fifteen hundred little children are worked like purchased slaves…. helping harvest this cranberry crop…The children, from 3-14 years of age or thereabouts, are driven with curses, urged with blows, and forced to live in condition that would shame a dog-breeder if he kenneled his animals in a place approximately as bad.”
Berry growers often lived in conditions like this.
The article called out Whitesbog, the bog that Elizabeth ran, specifically.
“The bogs of Mr. Joseph J. White… are considered to be the best in the state, so far as conditions of operation are concerned. This may be because they are under the supervision of his daughter. Here the housing is as perfect as it can be under the condition that requires the employment.”
Elizabeth responded publicly to attacks that she mistreated workers. For example, she wrote:
“That these efforts were ‘false or exaggerated in the light of my experience, …a grossly exaggerated picture of the evil in hopes of arousing public.’
She also defended the bog laborers, writing that
“These Italian cranberry pickers have an outing in the country and go home with many times as much money in their pockets as when they came. The good, steady-working (Italian) mother who can speak no English, and can never hope for work that pays much better; and I see what fine young women her daughters have become, speaking English easily. The children have the freedom of out-of-doors and the proud consciousness of earning their own school clothes. They come in close association with English-speaking Americans and both sides lose their prejudices. The children learn industry and thrift, drop the scabs of the… disease they brought from the city and grow rosy and plump. These and many other things like them I see year after year, and know that employment on the cranberry bogs, in spite of its occasional hardships, has furnished to many field-working Italian peasants a valuable stepping-stone, broken and imperfect though it may be, in their struggle upward into the more perfect American citizenship;, and by which they can earn much more than at most other work available for the newcomer who speaks no English, and at the same time enables them to give their children the advantages of the better schools in the city the greater portion of the term… If we can reconcile the fact that Nature’s chosen season of ripening the fruit clashes with man’s chosen time of starting children to school, make these picking seasons simply ideal outings for thousands of poor but self-respecting city people.”
The story of a woman growing blueberries may not seem revolutionary. But Elizabeth Coleman White’s story certainly demonstrated these characteristics. She explored science by using then state-of-the-art technologies to create a new, unimagined product—the domesticated blueberry.
Elizabeth touched the lives of many diverse people, including immigrant fruit pickers and poverty-stricken rural citizens. It was extraordinary that a rich businesswoman would promote immigrants’ rights, or work hand-in-hand with poor, rural Americans.
By introducing a new crop to the world market, Elizabeth pioneered a novel exchange. Before her work, blueberries were only a wild crop that picnicking children snacked on. A blueberry isn’t quite like a voyage to the New World, but Elizabeth certainly explored science, encountered a wide variety of people and societal hurdles, and altered American exchange.
A list of sources you can use to learn more about Elizabeth Coleman White can be found here.