Small nut trees in the Home Fruit and Nut Garden
All around the world we celebrate today, April 22, as Earth Day, and it is a perfect time to consider planting trees with edible fruits and/or nuts here on our lovely blue planet. If your planting space is small, here are some smaller nut tree suggestions. The dwarf siberian pine with edible pine nuts grows only to about 9 feet tall. A few of the smaller nut producers are actually more of a bush, like the Allegheny chinquapin, and some filberts (hazelnuts) make a great hedge, providing nuts for both you and the wildlife. There are some hybrid nut trees that will bear fruit in as little as 3 years, unlike the large walnuts and butternuts which take at least 10 years to fruit.
|Stages of hazelnuts||Baklava||Hazelnut shrub|
One of the best edible filberts is the European filbert, growing to about 15 feet tall. It thrives in cool, moist climates but is susceptible to winterkill. Here are a couple of filberts from PlantFiles: purple-leaf filbert (Corylus maxima ‘Purpurea’), zones 6 to 10. Hazelnut (Corylus americana) is a small hedge bush, native to the eastern U.S. Two plants are needed to set fruit and they can grow to 8 feet or more. They grow in zones 5 to 8 and their nuts ripen in August. The fruits are edible although often left for wildlife. The wild filberts in the eastern United States often carry Eastern filbert blight, a fungal disease. You should not plant European filberts if eastern wild filberts are growing close by. The wild western filberts do not seem to carry the disease.
Almonds (Prunus dulcis) are a stone fruit like peaches, but you eat the nut. Grown in zones 8a to 10b, they are produced commercially in California in the valleys where it is drier. Cross-pollination is required (hence the rental of honeybee hives by commercial groves). Raintree Nursery lists ‘Reliable’ as an almond that is easily maintained at about 12 feet tall, and is self-fertile. It is not a true almond, but a hybrid seedling of peach and almond for zones 5 to 9. There is an edible ornamental almond (Prunus amygdalus) said to grow 12 to 20 feet tall, bears in 3 to 4 years, is disease-resistant and self-fertile. Two varieties I have seen advertised are ‘Titan’ and ‘Halls Hardy’.
|Cashew ‘apples’ with nuts||Pistachios|
Cashew (Anacardium occidentale) is a fast growing evergreen tropical nut tree growing to a height of 30-plus feet. They are very susceptible to frost. Both the “apple” and the nut growing from the end of it are edible, and they contain five times the vitamin C of oranges. Pistachios (Pistacia vera) originated in Western Asia, where they are used in a variety of dishes; we probably know baklava best. The pistachio tree grows to 20 to 30 feet tall in zones 7a to 10b. They do well in the deserts if they are irrigated and have good drainage, but do poorly in high humidity and are subject to root-rot without good drainage. A male and a female are needed for fruit production.
Pine cone with edible nuts
|Piñon (Pinus edulis)||Piñon cone with nuts|
Pine nuts… oh my, there are so many… and they have been a food source for so long! Over 20 pine species produce edible pine nuts and of those, 5 are commercially important: Siberian pine (Pinus sibirica), Korean pine (Pinus koraiensis), Italian Stone Pine (Pinus pinea), Chilgoza pine (Pinus gerardiana) and singleleaf pinyon (Pinus monophylla), Colorado pinyon (Pinus edulis) and other pinyon (or piñon) species. The Korean Nut Pine is very hardy, tolerates clay soil, is resistant to white pine blister rust; and is a slow grower of medium height in zones 4 to 7. The Italian Stone Pine is not as winter hardy but it tolerates drought and heat better. It is the classic umbrella-shaped pine, said to grow in zones 7 to 9. Many of the edible pine nut trees also make great ornamentals.
Allegheny chinquapin shrub
One small nut tree I have on my list to order is the Allegheny chinquapin (Castanea pumila), which is basically a shrub or dwarf tree growing 12 to 15 feet tall in zones 3 to 9. The nut tastes similar to the native chestnuts that were wiped out by the chestnut blight beginning in 1912. It is said to have a more flavorful taste than the modern chestnut hybrids. There is another small chinquapin, the Georgiana chinquapin (Castanea alnifolia), which is more of a creeping 4-foot tall shrub that grows in zones 8 to 10. The Allegheny chinquapin prefers neutral soils, preferably somewhat uphill, and develops a taproot. The Georgiana chinquapin prefers shady, sandy thickets and spreads by very large, underground, shallow roots. Both produce numerous sweet nuts on the female trees, and a male is needed for pollination.
|Ginkgo nuts||Gingko leaves|
Although not small trees, there are some visually interesting trees we don’t generally think of for edible nuts. Those include ginkgo (Ginkgo biloba). Ginkgo, also called maidenhair tree, is the oldest broad-leafed tree on earth, with existing fossils 150 million years old. They grow to 50 to 80 feet tall and are grown in zones 3 to 9 although they do better in zones 4 to 7. They need a male to pollinate the female for fruit, and it can take up to 10 years to produce the first fruits. The 1-inch nuts are stir-fried or roasted and are prized in Chinese, Japanese and Korean dishes. They are also among the few nut trees that are not affected by pests or disease.
Another unfamiliar nut tree is the Monkey Puzzle tree (Araucaria araucana), which is an very sculptural looking tree. It is native to Chile and hardy to -10ºF, or zones 6 to 9. This evergreen tree is not self-fertile so you will need 2 to produce nuts. The 2-inch long nuts are grown on a large cone with as many as 250 nuts per cone. The nuts can be roasted and eaten like chestnuts, or dried and ground for use as a nut flour.
|Monkey Puzzle nuts||Monkey Puzzle nuts on branch|
Nuts are an excellent source of protein, averaging from around 20% to as much as 75% in butternuts. Most nuts also have a high fat content although most of the fat is polyunsaturated. Nuts also contain Vitamin E, many of the B vitamins, and some essential minerals like zinc and magnesium. Almonds are a good source of calcium. Nuts are also low glycemic so they break down slowly and do not cause a surge in insulin levels.
Is there space for a small nut tree in your garden?
Pinenuts: Species, Products, Markets, and Potential for U.S. Production, Leonid Sharashkin and Michael Gold, University of Missouri Center for Agroforestry,
Almonds on branch, iStockPhoto #4632901, used by permission
Ginko Nuts, iStockPhoto #1137307, used by permission
Ginko leaves, iStockPhoto #4794604, used by permission
Hazelnuts, iStockPhoto #4215418, used by permission
Piñon tree, iStockPhoto #1505385, used by permission
Piñon with nuts, iStockPhoto #3658859, used by permission
Pistachios on tree, iStockPhoto #4731667, used by permission
Cashews on tree, iStockPhoto #2769754, used by permission
Pine-cone nuts, iStockPhoto #2675140, used by permission
Baklava, public domain
American Hazelnut, Thanks to Equilibrium for her photo from PlantFiles
Allegheny chinquapin, Thanks to AYankeeCat for use of her photo
Monkey Puzzle Nuts: Thanks to Gustichock for the photo from PlantFiles
The World’s Smallest Fruit
Nature packages its seeds in botanical structures called fruits. Fruits come in an endless variety of shapes and sizes, from papery, inflated pods of locoweeds to fleshy berries of oranges and tomatoes. Since the January 1996 Wayne’s Word Noteworthy Plant was dedicated to the “World’s Largest Fruit,” it seems only fitting that the February 1996 Noteworthy Plant should be dedicated to the “World’s Smallest Fruit.” This lilliputian botanical controversy has come up in Professor Armstrong’s Biology 100 class on several occasions, and it is time to answer the question once and for all. Candidates for the title of “World’s Smallest Fruit” range from tiny individual seed-bearing drupelets of blackberries and figs to the biblical mustard seed. But none of these contenders even comes close. Is is no coincidence that the world’s smallest fruits are produced by the world’s smallest flowering plants. These remarkable plants belong to the genus Wolffia, minute rootless plants of the duckweed family (Lemnaceae) that float at the surface of quiet streams and ponds. In technical botanical terms, the fruit of these tiny aquatic plants is indehiscent, bladderlike, one-seeded and is often referred to as a utricle
The minute one-seeded fruits of Wolffia angusta compared with grains of ordinary table salt (NaCl). The fruits (utricles) were photographed in an ethanol (ethyl alcohol) solution and the salt grains have dissolved slightly resulting in rounded corners. The cubical salt grains are about 0.3 mm on a side. Fruits of W. angusta and W. globosa and are similar in size.
The minute one-seeded fruits of Wolffia angusta compared with grains of ordinary table salt (NaCl). The cubical salt grains are about 0.3 mm on a side. The fruits of W. globosa are similar in size.
Microscopic view of three cuboidal grains of ordinary table salt (sodium chloride or NaCl). All three grains are just over one millimeter in length (red bar). Grains of table salt vary slightly in size, but three average grains stacked together adds up to approximately one mm. If three grains equal one millimeter in length, then a single grain is approximately 0.3 mm or 0.03 cm on a side.
The world’s smallest fruits are produced by species of Wolffia, including the Australian W. angusta. The above image shows a mature fruit within the plant body. The larger fruit of Lemna shows a thin, transparent pericarp surrounding a ribbed seed. A pericarp layer is not evident on the wolffia fruits.
Two of the smallest species of Wolffia in the world are the Australian Wolffia angusta and the Asian/African Wolffia globosa. In fact, both species are so small that it is difficult to distinguish between the size of their fruits. Since the entire plant body of these two species is less than one millimeter long (less than 1/25th of an inch), the tiny mature fruit takes up most of its parent plant body. The fruit of W. angusta is only 0.30 mm long (1/100th of an inch) and weighs about 70 micrograms (1/400,000 of an ounce). One can get an idea of how small these fruits really are when you consider that an average, single, cubical grain of ordinary table salt (NaCl) is about 0.30 mm on a side and weighs about 60 micrograms. This fruit is smaller than the individual cells of many plants and animals, and is more than 4 billion times lighter than a massive world class pumpkin. So the next time you put a pinch of table salt on your favorite gourmet dish, think about the world’s smallest fruits which are approximately the size of one salt grain.
A tiny, budding Wolffia globosa plant and the minute one-seeded fruits of W. angusta compared with the eye of an ordinary sewing needle. The fruits are about 0.30 mm long. Fruits of W. angusta and W. globosa are similar in size and are the smallest fruits on earth.
Certain epiphytic orchids of the tropical rain forest produce the world’s smallest seeds weighing only 35 millionths of an ounce. They are dispersed into the air like minute dust particles or single-celled spores, eventually coming to rest in the upper canopy of rain forest trees. The world’s largest seed comes from the coco-de-mer palm (Lodoicea maldivica), native to the Seychelles Archipelago in the Indian Ocean. Although it belongs to a different genus from true coconut palms (Cocos), this enormous seed is often called the “double coconut.” A single seed may be 12 inches (30 cm) long, nearly three feet (0.9 m) in circumference and weigh 40 pounds (18 kg). It should be noted here that the largest seed does not have the largest embryo. In fact, palm seeds are mostly composed of endosperm tissue and generally have relatively small embryos.
Small seeds. Mustard family (Brassicaceae): Black mustard (Brassica nigra). Orchid family (Orchidaceae): Coral-root orchid (Corallorhiza maculata). Duckweed family (Lemnaceae): Watermeal (Wolffia angusta), a one-seeded fruit called a utricle. Poppy family (Papaveraceae): Opium poppy (Papaver somniferum). Without any doubt, the orchids have the record for smallest seeds. The seeds of some species are no larger than fungal spores and occur in a loose cellular sheath. Since the seeds have no endosperm and underdeveloped embryos, there are practically no food reserves. In order to germinate under natural conditions, they must establish a symbiotic relationship with a compatible mycorrhizal fungus. During early stages of development, the fungus supplies critical nutrients to the orchid seedling. Later the orchid may become fully independent, or it may retain its mycorrizal relationship throughout its life. The above coral-root orchid seed (Corallorhiza) grows into a nonphotosynthetic mycotrophic wildflower. It absorbs carbohydrates and minerals from its fungal host, which in turn absorbs these vital nutrients from the roots of nearby forest trees. Wolffia certainly has the record for smallest fruits which are not much larger than grains of ordinary table salt (NaCl). The single seed inside is almost as large as the fruit; therefore, wolffia seeds are not as small as orchid seeds.
Microscopic view of the seed of a coral-root orcid (Corallorhiza maculata). The individual seed is only about 0.2 mm in diameter. In fact, there are unusual bacterial cells that are larger than this orchid seed. The resolving power for an unaided human eye with 20-20 vision is about 0.1 mm. With its cellular sheath (seed coat) removed, this seed is barely visible to the naked eye. Certain epiphytic orchids of the tropical rain forest produce the world’s smallest seeds weighing only 35 millionths of an ounce. One seed capsule from a single flower may contain up to four million seeds. They are dispersed into the air like minute dust particles or single-celled spores, eventually coming to rest in the upper canopy of rain forest trees. The seeds of some species are no larger than fungal spores and occur in a loose cellular sheath. Since the seeds have no endosperm and a minute, undifferentiated embryo, there are practically no food reserves. In order to germinate under natural conditions, they must establish a symbiotic relationship with a compatible mycorrhizal soil fungus. During early stages of development, the fungus supplies critical nutrients to the orchid seedling. Later the orchid may become fully independent, or it may retain its mycorrhizal relationship throughout its life. The above coral-root orchid seed (Corallorhiza) grows into a nonphotosynthetic mycotrophic wildflower that is completely dependent on its mycorrhizal fungus. Throughout its life, the orchid absorbs carbohydrates and minerals from its fungal partner, which in turn absorbs these vital nutrients from the roots of nearby forest trees. In a laboratory, orchid seeds can be grown in nutrient agar, like a sterile (axenic) culture of bacteria or fungal spores.
Lemna aequinoctialis from the Sierra San Francisco of Baja California. This view shows the basal root sheath with two lateral wings and a one-seeded fruit (utricle) protruding from a lateral budding pouch. The number of longitudinal ribs on the seed (faintly visible through the transparent pericarp) indicates that this species is L. aequinoctialis and not L. perpusilla. The head of an ordinary straight pin is used for a size relationship. It is 1.5 mm in diameter.
Straight Pin Used In Wayne’s Word Articles
There are several animal reproductive disseminules in fresh water that are about the same size as wolffia seeds and fruits. They range in size from 0.2 – 0.6 mm and often show up in wolffia samples from ponds and streams. The following reference clearly determines that they have an animal origin and not reproductive bodies of duckweeds:
- Pennak, R.W. 1953. Fresh-Water Invertebrates of the United States.
The Ronald Press Company, New York. 769 p.
The brown, disk-shaped structures mixed with these populations of Wolffia columbiana and W. borealis in the San Dieguito River of San Diego County are not wolffia fruits. They are asexual reproductive bodies called statoblasts from a freshwater bryozoan (possibly in the genus Plumatella). Bryozoans are colonial animals in the Phylum Bryozoa. The chitinous statoblasts are produced in large numbers and are dispersed by water currents where they germinate (hatch) and develop into new colonies.
Left: Close-up view of a freshwater sponge (possibly the genus Spongilla) showing needlelike, siliceous spicules which provide the structural skeleton to support the flimsy tissues of the body. Scattered in the sponge body are several spherical gemmules. These are resistant reproductive structures similar in function to the statoblasts of freshwater bryozoans. The structure of gemmules and spicules are used to identify different species of freshwater sponges. Right: Microscopic view of several gemmules. Each gemmule is covered with a protective outer layer and a foraminal aperture. In some species the gemmules are also covered with spicules. Gemmules are commonly produced during the fall, and like the overwintering turions of duckweeds, are able to survive severe winter conditions. They are commonly collected in duckweed samples. The gemmules can withstand repeated freezings and thawings and may be viable for three years are more. Upon germination, a creamy mass of amoebocytes slowly flows out of the foraminal aperture. The amoebocytes differentiate into the several tissue types of the new developing sponge. The following photo of tropical beach sand shows shiny, 3-pronged spicules of a marine sponge.
A magnified view of the tropical beach sand from the Caribbean island of St. John (U.S. Virgin Islands). The grains include porous fragments of brightly-colored corals, minute foraminiferan shells, fragments of sea shells and shiny, star-shaped sponge spicules.
Types of Nuts
Hickory nuts: There are several varieties of hickories, some producing sweet nuts, others producing bitter nuts. Of the sweet variety, the shagbark and the shellbark are the most well known. Shagbark hickory nuts are thin-skinned and easy to shell. Shellbark hickory nuts are larger than shagbark with thicker shells. Both are similar in flavor to pecans and have a limited commercial production. The bitter hickory nut is used to flavor hickory-smoked cured meats.
Macadamia nuts: These “gourmet” nuts were named for Dr. John Macadam, an Australian who reputedly discovered that they were deliciously edible. Indigenous to Australia and now one of the best-known products of Hawaii, macadamias have a sweet, delicate taste and creamy, rich texture. However, they contain more fat and calories than any other nut. On the plus side, macadamias supply some iron, magnesium, and thiamin. Most commonly eaten as a dessert nut, macadamias are nearly always sold shelled because their shiny round shells are thick and require some 300 pounds of pressure to crack. They are harvested five or six times a year, but the demand still exceeds the supply. Consequently, they’re usually quite expensive.
Peanuts: Peanuts are actually a type of legume, but are commonly used as nuts.
Pecans: Similar to the walnut in taste and appearance, pecans are available shelled and unshelled. Shelled pecans come as halves or pieces. There are roasted and salted versions as well.
Pine nuts: Pignoli, pine nuts, piñon nuts, pinyon nuts, and Indian nuts are all names for the seeds of various types of nut pine trees, which grow in several areas of the world. The seeds come from pinecones and range in size from that of an orange seed to more than 2 inches in length. To harvest the nuts, the pinecones are dried to free the nuts, then the nutshells are cracked to release the kernels. Because of the intricacy of harvesting pine nuts, they are quite expensive. Slender ivory-colored pignoli are an important cooking ingredient in the Mediterranean region, while the pinyons of the American Southwest have been a staple of the Native American larder since ancient times. In general, European species of pine nuts are richer in protein and lower in fat than the American varieties, but American pine nuts offer more vitamins and minerals. Pine nuts are available in Europe, as well as Russia and China. Imported pine nuts are usually sold shelled where American pine nuts—or pinyons—are sold both ways, in-shell and shelled.
Pistachio nuts: Related to peaches, mangos, and cashews, pistachios are buttery, sweet, and delicate-flavored. Over the years they have grown in popularity as a snack food in the United States.
Walnuts: Walnuts are available shelled (in halves and pieces) and unshelled. They are also processed for their oil and are one of the few sources of alpha-linolenic acid, an omega-3 fatty acid found only in plant foods.
Nut Trees In Containers: How To Grow A Nut Tree In A Pot
In this day and age, many folks are living in homes with a smaller footprint, often lacking any sort of garden space, so lots of people are container gardening. While this generally involves small crops or flowers, there are dwarf fruit trees on the market suited for growing in containers. What about nut trees? Can you grow nut trees in pots? Let’s learn more.
Can You Grow Nut Trees in Pots?
Well, growing nut trees in containers is generally a little problematic. You see, typically nut trees run about 25-30 feet (8-9 m.) in height, making container grown nut trees size prohibitive. That said, there are some nut varieties that have better potential for use as container grown nut trees than others. Read on to find out how to grow a nut tree in a pot.
How to Grow a Nut Tree in a Pot
The best nut tree to grow in a container is the pink flowering almond. This small almond only gets to about 4-5 feet (1-1.5 m.) in height. This gorgeous tree offers stunning bi-color pink blossoms in the spring and vibrant yellow autumn color. Additionally, the tree is very resilient, easy to care for and even fairly drought tolerant, all which make growing this type of nut tree in a container a win-win.
Be sure to use a well-draining potting soil and make sure that the pot you use when growing nut trees in containers has sufficient drainage holes. Water the tree weekly; check the soil to be sure it has dried out a few inches down. If the tree is still moist, hold off on watering for a day or two.
This flowering almond tree is resistant to frost damage but when nighttime temps drop below 45 F. (7 C.), bring the tree indoors. Place the tree in a sunny window that gets plenty of afternoon sun. Unlike citrus trees that over winter in containers indoors, this almond isn’t picky about humidity; it actually prefers dry, arid conditions.
As to growing other types of nuts in containers, there are some hybrid nut trees that bear fruit in as little as 3 years. There are also some filberts (hazelnuts) that become more of a bush, which have potential for growing in a pot, but I would think since you need two plants to set fruit and they can grow to about 15 feet (4.5 m.) in height, they aren’t for anyone concerned with saving space.
Really, the only other potential containable nut tree I can think of is one that produces pine nuts. There are five of commercial importance and of these, the one that would be most ideal grown in a container is the dwarf Siberian pine, which only gets to about 9 feet (under 3 m.) in height and is very cold hardy.
Of course, it’s perfectly fine to start nearly any nut tree in a container and then transplant in a suitable location once reaching a foot or so in height.
Pecan Planting Guide
Selecting a Variety
In selecting a pecan variety for your yard, disease resistance is the most important factor. Other factors to consider are tree size, productiveness, attractiveness of the tree and nut, and quality of the nut. Suggested pecan varieties for the home are listed in two groups: (1) those that come into production fairly early, 5-6 years, such as Desirable, Cape Fear, Elliott, and Pawnee; and (2) those that require 8-10 years for production, such as Stuart, Gloria Grande, and Forkert. To determine the ideal variety for you, please consult Plant Me Green’s Pecan Variety Guide which can be found on our website.
Care Before Planting (Heeling in Your Plant)
Realize that all bare root stock, though dormant, is also in a state of shock. They have been dug up from the field with an inevitable loss of roots, and need special care even before planting. The most important thing to remember is KEEP THE ROOTS MOIST. Even for brief periods, i.e. while transporting them to the planting site. If you have not pre-dug the holes for your trees and must keep them for more than a few days, they should be HEELED IN (buried in a moist medium), in a shady spot and watered thoroughly. Keep the roots packed in sand, peat moss, potting mix or aged sawdust (avoid fresh sawdust or wood shavings as they may contain compounds that inhibit root formation). Trees can be kept like this for several weeks if necessary, but should always be permanently planted before showing any signs of bud swell or growth. Protect trees from freezing before planting. Prior to planting, SOAK TREES IN WATER FOR 12 TO 24 HOURS. This will afford them a good long drink to compensate for any moisture loss in storage and shipping.
Selecting Best Planting Site
The most important factors to consider in choosing a site for planting pecan trees are: soil type, depth, and drainage.
Pecans will grow in almost any soil in southern states, except poorly drained soil, hardpan or stiff clays, or thin sands with a high water table. Soils for planting pecan trees may be red, brown, or gray in color, but it is necessary they contain sand or sandy-loam and that the subsoil be of clay or semi-clay structure. It is most important that the soil should have good water holding capacity. For proper root penetration, it should be several feet deep.
In selecting a planting site, keep in mind the desirable soil characteristics described above. Avoid badly eroded hills. If not eroded, hilltops and north, east, south, or west slopes are satisfactory. In most cases, even bottom land along streams has proved a good location if well drained. The greater movement of the air often causes faster drying of morning dews and rains which help prevent scab infection.
In addition to the above, select a planting site away from buildings and power lines. Always consider the mature size of pecan trees when deciding on a planting site. If planting more than one pecan tree, space at least 40-60 feet apart so they have adequate space to grow.
Pecan trees can be planted as bare-root or container-grown. Bare-root pecan trees should be transplanted during the dormant season; mid December through early spring are preferred. Container-grown trees are less likely to receive transplant shock if planted while dormant, but with adequate attention and irrigation, they can be planted October through June.
To plant, dig a hole at least 24 inches wide at the bottom and 2 ½ to 3 feet deep. If planting bare-root, soak roots in water for 24 hours just prior to planting. Examine the roots and remove all broken or injured roots but keep root trimming to a minimum. Occasionally the taproot and/or some of the lateral roots will need to be pruned to fit the hole. Never twist lateral roots in the hole as this could eventually cause death to that part of the root system.
Plant the tree level with where it grew in the nursery (i.e. the soil line, which is indicated by a color change on the bark) but not too deep. Fill the hole about ⅓ full of topsoil and saturate the soil with water to settle, repeating this operation until the hole is almost full. Have a soil test done to determine the pH level of the soil, and if the soil is below 5.6 add lime to your soil as the hole is being filled to raise the pH. Once the hole is filled, construct a basin around the tree 3 or 4 feet in diameter and 6 to 8 inches deep.
During the first growing season, water the trees once a week on clay soils and twice a week for light soils. The roots of a bare-rooted tree help to provide anchorage and to serve as a source of new feeder roots following transplanting, but they are of little value in direct absorption of moisture and nutrients from the soil. New roots are necessary for this function, and they develop from the older roots. The tree must remain alive during the critical period of new root development, which is slow. So, for this reason adequate moisture must be available to the tree throughout the entire first summer.
As soon as trees are set, prune the top to balance with the roots. For bare root, prune ⅓ to ½ of the top, and for container pecans, prune about 10 percent off the top. Make the cut just above a healthy bud.
Care of Young Non-Bearing Trees
To get good growth, prune no more than necessary. The larger the number of leaves left to grow, the more food will be manufactured for more rapid tree growth. Cut out narrow crotches early to prevent serious splitting when the tree comes into heavy production. Try to space the lateral limbs equally around the trunk of the tree, and have each limb at least 8 inches above another. Select three to five branches for the permanent scaffold system. The lowest of these branches should be no less than 6 feet above the ground.
The pH range for pecans should be from 5.6 to 6.5. To determine the pH, have the soil tested through your local county extension agent, and he or she in turn will suggest the amount of dolomitic limestone to apply, if any is needed.
Newly transplanted trees should NOT be fertilized at the time of planting, but should receive 2 to 3 pounds of 8-8-8 or 10-10-10 containing at least two units of zinc per tree in May the year they are transplanted. Be sure to keep the fertilizer at least 12 inches away from the trunk. Each succeeding year until the tree begins production, apply 1 pound of 8-8-8 or 10-10-10 plus minor elements for each inch of trunk diameter measured one foot above the soil surface – apply in late February or early March.
Strive for an average terminal growth of about 3 feet annually. If the growth is shorter than this, apply additional nitrogen at the rate of ½ to 1 pound of ammonium nitrate or an equivalent amount of nitrogen from another source of quickly available nitrogen.
For their first three years, pecan trees require 10-15 gallons of water at regular weekly intervals either through rainfall or irrigation.
Pollination and Fruiting Habit
The male flower and the female flower of the pecan are separate, but they are on the same trees. The male flowers, commonly known as catkins, are produced from lateral buds on the previous season’s growth. These buds are formed late in the previous season.
The female flower, a tiny nut-like flower with flared terminal ends, is produced at the end of the current season’s new growth. The flared ends (stigmas) of the tiny nuts are the portion of the female flower on which the pollen falls when pollination occurs. Since the female flowers are borne on the current season’s growth, the tree must have stored an abundance of food from the previous season. Also, an adequate amount of fertilizer should be applied early enough – late February or early March – to be effective.
Pecans are pollinated by wind only. When the catkin matures, the pollen is released. The pollen floats in the wind, and by this means it reaches the flared tips or stigmas of the female flower. Pollination then occurs if the pollen is viable (alive) and the stigma is receptive. Should the catkins mature before or after the female flower is receptive, pollination does not occur. And should heavy rains occur during pollination, the pollen will not be wind borne and pollination will be poor. Thus, to assure pollination, it is important to plant more than one variety in an area.
Care of Bearing Trees
To realize good annual production, trees must be adequately fertilized and insects and diseases controlled. You can determine whether an adequate amount of fertilizer has been applied by the amount of terminal twig growth. An average annual growth of 6-8 inches is ideal, with 4 to 6 inches as the minimum, if trees are expected to produce large crops.
The recommended fertilizer program should be determined by your soil test but a general rule is to apply 4 pounds of 8-8-8 or 10-10-10 fertilizer per inch of trunk diameter measured 4 feet above the soil line. Apply fertilizer in late February or early March. On sandy soils split application can be made – the first half being applied in late February or early March and the second near blooming time in May. To prevent deficiency of zinc and other minor elements, the 6 fertilizer listed above should contain 1 to 2 percent of the deficient minor element(s). Lack of enough zinc and nitrogen reduces production more than any other factor.
Apply fertilizer beneath the spread of the limbs and beyond the edge of the limbs to a point equal to the distance from trunk to limb-spread. If a lawn grass is not present, broadcast fertilizer on the soil surface and water into the soil. Where trees are in the lawn, do not spread the fertilizer on the surface as injury to the grass may result. Instead place fertilizer beneath the soil surface by plugging or probing.
Use post-hole digger, probe, or orchard auger to place the fertilizer below the soil surface. If a post-hole digger or auger is used, remove the sod plug and then dig a hole about 6 inches deep. Place the fertilizer in the hole, replace the soil, pack, and replace the sod plug. If a probe is used, it should be at least 1 inch in diameter and have a sharp point. Force the probe into the soil about 12 inches deep. Remove the probe, and fill the hole with fertilizer up to within 3 inches of the top. Close the top of the hole by packing the soil along the side with the heel.
Zinc deficiency is called rosette. The most common and noticeable symptoms of rosette are the following: bronzing and mottling of leaves; early defoliation; dead twigs in top of trees; abnormally small nuts; small yellowish chlorotic leaves; short thin twigs growing on older scaffold branches with rosette of small yellowish green leaves at the tips. An early sign is wavy margin of the leaflets.
The most important factor influencing yield is proper fertilization including zinc to prevent rosette. Controlling diseases and insects is equally essential.
Pecan trees tend to exhibit alternate bearing, meaning that a high production year is followed by one or more years of low production. This happens when trees set a large nut crop and nutrients and moisture are not enough for the nuts to mature and for the tree to store enough plant food causing low production the following year. Early defoliation in the fall usually means no nut crop the next year.
Diseases and insects affecting the leaves also contribute to alternate bearing by causing early leaf drop in the fall. To help prevent alternate bearing, use sound cultural practices. These include disease and insect control, adequate use of fertilizer and zinc, and an extra application of fertilizer in late May or June in years when nutset is heavy. Keeping healthy, dark green leaves on the tree until first frost is a sure step toward achieving annual nut production.
Growing nut trees in your back yard or orchard
CORVALLIS, Ore. – Oregonians who love the variety of nuts that grow in the state, and would like to harvest their own every year, have the opportunity to grow butternuts, chestnuts, hazelnuts and walnuts in their back yard or orchard.
Detailed advice on how to do it is available in an Oregon State University Extension publication, “Growing Tree Fruits and Nuts in the Home Orchard” (EC 819), which is available online.
Before deciding to plant nut trees, ask whether you will have the time and interest to prune, spray, harvest and use what could become abundant crops. Also, consider the space needed and available soil.
“Large trees such as walnuts and chestnuts make good shade trees, but they’re more difficult to prune and spray than smaller trees,” said Jeff Olsen, OSU Extension horticulturist. “The soil must permit rooting to a depth of at least three feet. Too much sand or clay can be a problem, although some kinds of trees will tolerate extremes of soil texture.”
Here are some of Oregon’s most popular and common nut varieties.
Butternuts. The butternut tree closely resembles black walnut. It’s the most winter-hardy of all nut species, the most likely to succeed in poor soil and can be grown throughout the state. It’s an attractive landscape tree because of its gray bark and interesting tree form. The nut is pointed and oblong with deep ridges and in most varieties, difficult to remove from the shell.
Chestnuts. Also grown everywhere in Oregon, chestnuts grow into large, attractive shade trees that bear fragrant, creamy white catkins in spring. Nuts are enclosed in golden-colored prickly hulls in the fall. The nuts are delicious roasted fresh, but they mold easily in storage. Although the trees will bear some nuts with their own pollen, pollen from a second tree will often increase nut production and size.
Hazelnuts. Unless you remove suckers from the crown of a hazelnut tree every year, it grows as a bush. You can propagate hazelnut trees from rooted suckers, but nurseries usually can supply better trees. Every hazelnut variety requires another variety for pollination. To increase a tree’s productivity, prune out the older, more downward-hanging wood. Make sure to plant hazelnut varieties that are completely resistant to Eastern Filbert Blight, which has killed many trees. Examples of blight-resistant varieties include “Jefferson,” “Santiam,” “Yamhill” and “Gamma.” Hazelnuts grow only in the Willamette Valley and coastal regions of Oregon.
Walnuts, black. Black walnut trees grow rapidly into very large shade trees. The nuts are delicious but hard to crack. Like English walnuts, they’re subject to infestation by the walnut husk fly. Varieties available from nurseries usually have larger kernels and are easier to crack than seedlings. They grow only in the Willamette Valley and mid-Columbia and eastern Oregon regions.
Walnuts, English. Trees make good nut-bearing shade trees in western Oregon, but are subject to several serious problems. Early fall and winter freezes frequently damage or kill walnut trees. Early-blooming varieties are subject to spring frost and infestation of the husk fly. Hardy Carpathian walnut varieties can be grown in the mountain and high plateau areas of the state.