- Grapevine Fertilizer: When And How To Fertilize Grapes
- Fertilizing Grapevines Prior to Planting
- When to Feed Grapevines
- How to Fertilize Grapes
- The Best Fertilizer for Grapes
- A Range of Benefits
- Soil sampling vineyards and guidelines for interpreting the soil test results
- Fertilizing Grape Vines
- How to Fertilize a Grape Vine
- How Much and What Kind of Fertilizer to Use
- Table grape growing, non commercial
- Trellising and vine training
- Watering and fertilising
- Spur pruning
- Cane pruning
Grapevine Fertilizer: When And How To Fertilize Grapes
Most types of grapes are hardy in USDA growing zones 6-9 and make an attractive, edible addition to the garden with minimal care. To get your grapes off with their best chance for success, it’s advisable to do a soil test. The results of your soil test will tell you if you should be fertilizing your grapevines. If so, read on to find out when to feed grapevines and how to fertilize grapes.
Fertilizing Grapevines Prior to Planting
If you are still in the planning stages with regards to grapevines, now is the time to amend the soil. Use a home testing kit to determine the makeup of your soil. Generally, but dependent upon the grape variety, you want a soil pH of 5.5 to 7.0 for optimal growth. To raise a soil pH, add dolomitic limestone; to lower a pH, amend with sulfur following the manufacturer’s instructions.
- If the results of your test show the soil pH is fine but magnesium is lacking, add 1 pound of Epsom salts for each 100 square feet.
- Should you find your soil is lacking in phosphorus, apply triple phosphate (0-45-0) in the amount of ½ pound, superphosphate (0-20-0) at the rate of ¼ pound or bone meal (1-11-1) in the amount of 2 ¼ pounds (6 ¾ cups) per 100 square feet.
- Lastly, if the soil is low in potassium, add ¾ pound of potassium sulfate or 10 pounds of greensand.
When to Feed Grapevines
Grapes are deep rooted and, as such, require little additional grapevine fertilizer. Unless your soil is extremely poor, err on the side of caution and amend as little as possible. For all soils, fertilize lightly the second year of growth.
How much plant food should I use for grapes? Apply no more than ¼ pound of 10-10-10 fertilizer in a circle around the plant, 4 feet away from each vine. In successive years, apply 1 pound about 8 feet from the base if the plants appear to lack vigor.
Apply plant food for grapes just when the buds begin to emerge in the spring. Fertilizing too late in the season can cause overly extensive growth, which may leave the plants vulnerable to winter injury.
How to Fertilize Grapes
Grapevines, like almost every other plant, need nitrogen, especially in the spring to jump start rapid growth. That said, if you prefer to use manure to feed your vines, apply it in January or February. Apply 5-10 pounds of poultry or rabbit manure, or 5-20 pounds of steer or cow manure per vine.
Other nitrogen-rich grapevine fertilizers (such as urea, ammonium nitrate and ammonium sulfate) should be applied after the vine has blossomed or when grapes are about ¼ inch across. Apply ½ pound of ammonium sulfate, 3/8 pound ammonium nitrate or ¼ pound of urea per vine.
Zinc is also beneficial to grapevines. It aids in many plant functions and a deficiency can lead to stunted shoots and leaves, resulting in a reduced yield. Apply zinc in the spring a week before the vines bloom or when they are in full bloom. Apply a spray with a concentration of 0.1 pounds per gallon to the vines foliage. You may also brush a zinc solution on fresh pruning cuts after you prune your grapes in the early winter.
Decreased shoot growth, chlorosis (yellowing) and summer burn usually mean a potassium deficiency. Apply potassium fertilizer during the spring or early summer when the vines are just beginning to produce grapes. Use 3 pounds of potassium sulfate per vine for mild deficiencies or up to 6 pounds per vine for severe cases.
The Best Fertilizer for Grapes
The careful process of growing grapes has been studied for centuries, all over the world. Finding the perfect balance of nutrients to grow the crispest grapes as early as possible is a challenge that continues to face grape growers. We tackled this challenge with science, performing extensive research on wine, juice, and table grapes to find the ideal fertilizer for different varieties.
Our grapevine fertilizer program is designed to give grapevines a balanced combination of nutrients, bolstering the health of the plant and helping more nutrients reach the fruit. Using soil testing, tissue sampling, Brix testing and other analyses, we formulated the best fertilizer for grapes to improve yield, taste, and vine health.
A Range of Benefits
Sure-K and Kalibrate liquid fertilizer products will provide the essential potassium – and sulfur when needed – for healthy growth. The slow-release technology in these products, combined with balanced micronutrients, improved the vines’ ability to process and transport sugars throughout the plant. This, in turn, improved the size, appearance, taste and growth of the grapes. In addition to the improved quality, the grapes were also ready to be harvested earlier in the season.
Soil sampling vineyards and guidelines for interpreting the soil test results
Spring is a good time to test the soil nutrient levels in your vineyard. For established grapes, you are monitoring changes in nutrients, pH and organic matter over multiple years. Organic matter content and pH impact nutrient availability in the soil. Extractable nutrients tend to be lower in fall after harvest. Soil pH tends to be higher in spring than fall. To be able to more easily compare soil nutrient changes in the vineyard from year-to-year, it is advisable to make soil tests at the same time of year. For established vineyards, testing every two to three years is adequate. Michigan State University offers soil testing services at the Soil and Plant Nutrient Laboratory. There are also a number of private labs that can test soil.
To sample soils properly, you need a few tools: a soil probe, trowel or spade; a clean plastic pail; sample bags or boxes; a map of your vineyard; and a marker. Separate the vineyard into smaller sections with relatively similar soil texture, slope, organic matter and cropping history. Mark the areas you are testing on the map so that you can retest the same locations next time for comparison.
Sample the vineyard in a zigzag fashion, five acres or less per sample. If your vineyard is very uniform, then no more than 10 acres per sample. Avoid sampling from the ends of the rows and the edges of fields. Collect soil to a depth of 8 inches from 15 to 20 locations, mix them thoroughly in the plastic pail and take out a pint of soil for testing. Testing forms and soil boxes for the MSU soil lab are available at your Michigan State University Extension county office or by contacting the lab.
Cation exchange capacity (CEC) is a measure of the fertility or nutrient holding capacity of the soil. The CEC is calculated by adding together the amount of soil values of potassium (K), calcium (Ca), magnesium (Mg) and hydrogen (H) held on the soil particles. The greater the clay and organic matter content of the soil, the higher the CEC. Nutrient levels and pH tend to be more stable in soils with higher CEC. In soils with a CEC less than 6me/100g K, Ca and Mg may change more rapidly.
Loamy sands and sands usually have a CEC less than 8. The CEC of sandy loams frequently falls between 8 and 12. Loams, clay loams and clays usually have a CEC greater than 12. As the soil pH changes, the CEC value will also vary somewhat. The higher the CEC, the greater the capacity of the soil to hold nutrients.
Soil pH for grapes. pH is a scale used to measure acidity or alkalinity. The pH scale is from 0 to 14. A value of 7 is neutral, less than 7 acidic and greater than 7 alkaline. A soil pH in the range 5.5 to 6.5 is considered optimum for grapes and generally has better nutrient balance for plant growth than soils that are more acidic or alkaline. Vines will grow from pH 4.0 to 8.5, but a pH below 5.5 and above 8 will depress yields and create vine problems. Soil pH affects the availability of nutrients and microbial activity in the soil. The availability of many micronutrients (Mn, Cu, Zn and B, for example) decreases as soil pH increases. Soil pH often drifts down over time with the use of fertilizers and sulfur.
Adjusting soil pH
- Below 5.5: Bring up to 6.0 or 6.5 with lime. Dolomitic limestone will also help raise the magnesium value if it is low. Calcitic limestone will help raise calcium levels.
- Above 7.0: Consider lowering to 6.5 or 6.0 with sulfur, or using acidifying fertilizers such as urea or ammonium sulfate.
Soil organic matter. Organic matter (OM) improves soil structure, moisture retention and fertility. Two to 3 percent is considered ideal for grapes. Nitrogen is released from organic matter at approximately 20 pounds N per acre per year for each 1 percent of organic matter present. So at the optimum 2 to 3 percent OM for grapes, there is 40 to 60 pounds N per acre per year released from the soil. Grapes grown on high organic soils tend to be less winter hardy. With the indeterminate growth habit of grapes, excessive N promotes vegetative growth late into fall, and shoots don’t have time to acclimate for winter.
Recommended application amounts for potassium and phosphorus will be listed on the soil test results. Nitrogen recommendations will also be listed. Usually, half the nitrogen should be applied at bud break and the other half at bloom. Nitrogen applications should be completed by veraison, allowing vines to take up and use the nitrogen during the growing season. Nitrogen applied during the mid to late summer will encourage vegetative growth into the fall season, when vines should be hardening off and preparing for dormancy.
Source: Midwest Grape Production Guide
- Wine Grape Production Guide for Eastern North America, Tony Wolf et al.
- Grapevine Nutrition, Mark Chien, Penn State Cooperative Extension
- Midwest Grape Production Guide, Ohio State University
- Ontario Crop IPM soil diagnostics
- Monitoring grapevine nutrition, USDA-ARS and Oregon State University
- Raising Soil pH and Soil Acidification, University of Minnesota
- MSU Soil and Plant Nutrient Laboratory
It only takes a few minutes of reading anything about wine for soil to come into play. Whether it’s a long feature on Germany’s Mosel region, or the shelf-talker at Bevmo, experts, sommeliers, and marketers love throwing in tidbits about the ground that makes their wares extra special.
Luckily, you don’t have to go licking rocks (though some sommeliers do) to understand how fancy lingo like “clay loam” and “well-drained limestone” make grape-growing possible and the resulting wine delicious.
Soil does two things for wine. It impacts how grapes absorb (or don’t absorb) nutrients, and it provides drainage for the roots of grapevines. There are, of course, lots of other nuances that contribute to the terroir of a wine and exist in the soil, like concentrations of iron or nitrogen, for example. But when it comes to the huge difference between a vine that is thriving, versus one that’s just surviving, pH and drainage are the major players.
Grapevines are a hardy crop, which allows them to ripen almost anywhere. But the best grapevines (and resulting wines) come from balanced vineyards, where water, nutrient, and underground Nirvana align with the sun-soaked environment above ground. The phrase “moderation in all things” applies to vineyards as well as chocolate and Netflix binges.
When it comes to drainage, that means providing vines with enough water to thrive, but not so much that the roots end up waterlogged and prone to rot or root diseases.
In winemaking, “drainage” refers to the ability of the soil to retain water. Essentially, gravelly, loose, sandy soils allow rainwater to rush away from the roots of grapevines. Clay and volcanic soils retain water, keeping it in place and available for thirsty grapevines.
For example, the stony island of Santorini, which produces some of Greece’s most famous (and most delicious) white wines, is made up primarily of hard, crumbly volcanic soil. In the dry Mediterranean, this soil retains the small amount of annual rainfall, allowing grapes to ripen. Here and in other arid regions like central Portugal, water retention is historically what allowed vines to flourish before modern irrigation systems. In wet, rot-prone areas, well-drained soils did the opposite, allowing vines to grow and preventing root diseases. Most regions combine a mix of soil types, either due to erosion or historical events like massive floods, glacial movement, or volcanic eruptions. In a moderate climate, like Napa Valley or Bordeaux, where moderate temperatures and adequate rainfall collide, that mix is a good thing.
When growers plant new vineyards, a large part of soil evaluation involves looking at drainage to determine how much water will be retained in the soil. Specific rootstocks have even been designed to grow better in well-drained and poorly-drained environments.
Once grapes have enough water, they look to the soil for other nutrients they need to thrive, like iron, nitrogen, and phosphorus. But the existence of these and other minerals in the soil doesn’t necessarily contribute to the wines, which is why pH is so important in vineyard soils.
The pH scale measures the acidity or alkalinity of a substance, and in soil that contributes to how available those nutrients are to vines. Soil pH has a huge range from three to 10 (on a scale of 14). Grapes can be grown throughout that range, but soils closer to the neutral rating of seven are preferred. These soils, coupled with adequate water, have a chemical makeup that encourages what’s called “cation,” the fancy scientific word for nutrient absorption by vines. Grape lunch, as I like to call it.
Between the pH of 5.5 and 7.0, the cation rate, or ability of grapevines to absorb the nutrients in the soil around them, increases, making more nutrients available and easily digestible for grapevines. It enables them to absorb everything they need to grow properly, rather than struggle along, like eating a healthy diet versus surviving on vending-machine fare. Some research also suggests that soils in this range allow grape berries to retain more acidity as they ripen, leading to brighter, more acidic finished wines. In Champagne, Burgundy, and Santorini, growers often attribute the finesse of their wines to the high pH found in calcium-rich soils.
Together, pH and drainage form the baseline for the success of grapevines across the world. While other factors like temperature, fertilizers, and cover crops also play a role, these simple elements remain critical.
Next time you’re in a vineyard, don’t look at the grapes, look at the ground.
Fertilizing Grape Vines
What do you think of Kelp as a fertilizer for grape vine? I’ve got 50 grape vines; St Pipen, St Croix and Foch. What fertilizer is best?
Kelp contains .9% nitrogen, .5% phosphorous and 1 to 4% potassium and has been used for fertilizing ornamental and food crops. Sea kelp does contain sodium in several forms. No matter what fertilizer you prefer it is best to start with a soil test. This will tell you what type and how much fertilizer your grapes need. Your local University Extension service can provide information on how and where to have your soil tested. Plus many states are requiring soil tests before you can apply fertilizers containing phosphorous. If you skip the test consider with a low nitrogen slow release fertilizer like Milorganite. Most urban soils have high to excess levels of phosphorous and potassium. So before adding more make sure you need it. Many books and pamphlets recommend 10-10-10 fertilizers. The idea is to keep things in balance. But most plants do not use these nutrients in equal amounts resulting in a build up of phosphorous and potassium in the soil. So test first for best results.
How to Fertilize a Grape Vine
Grapes have been bred to grow in almost every climate and every type of soil. Table grapes, wine grapes and raisin grapes have similar growing needs. Once your grape vines are established, you can expect them to produce crops for up to 40 years. Knowing when and how to fertilize your grape vines will keep them healthy and productive.
Grape flowers and fruits grow only on new growth from cane buds that formed the previous year and were dormant over the winter. Grape vines need well-developed root systems to produce good fruit year after year, so soil structure is an important factor.
How Much and What Kind of Fertilizer to Use
First year plantings of grape vines do not require fertilizer. They will expend energy on developing roots during their first season, so if you feel obligated to provide fertilizer, use something with low nitrogen (N), high phosphorus (P) and low potash (K). Bone meal is a good organic source of phosphorus; for new grape vines, mix about one teaspoon of bone meal into the planting hole. Nitrogen fertilizer will encourage excessive leaf growth instead of the root system the grape needs to make it through the winter. Phosphorus will encourage root development.
The optimum soil pH (acidity level) is between 5.0 and 6.0. Do soil testing before adding any corrective lime. Grapes will grow quite nicely in soil that falls outside the realm of the perfect pH.
Keep competitive weed growth at least 2 feet away from the vines on each side. Manage weeds with organic mulch and by pulling and hoeing.
The second year after planting grape vines, you might want to fertilize lightly with a layer of compost or use a balanced 5-5-5 organic fertilizer one time in the early spring just as the vines break dormancy. Keep compost or fertilizer at least 6 inches away from the trunk of the vine.
The third year and thereafter, a light layer of compost in the early spring is all your grapes should need.
Grapes have a symbiotic relationship with mycorrhizae, which are naturally occurring fungi that live in the grape roots and aid in the breakdown and absorption of nutrients from organic material. This is one reason why the layer of compost and organic mulch is so efficient in providing the needs of grape vines. Avoid using garden chemicals, which will upset the balance of mycorrhizae.
Grapes (Vitis vinifera) have the reputation of being fragile and difficult to cultivate. In fact, many home gardeners are convinced that growing organic grapes in your backyard is far too complicated and not worth the effort.
Fresh fruit lovers (and winemakers) rejoice! A number of grape varieties are well-suited to the colder regions of every state and they are now grown in almost every part of the country, including Montana where I live. The trick is choosing the right grapevines for your hardiness zone.
Once established, a well-tended plant (or vinyard) can be productive for 40 years or more. Plus you’ll have peace of mind knowing that the sweet, juicy fruits you harvest contain no chemical residues, unlike the non-organic kinds found at the supermarket.
Fun Fact: The United States has been the world’s largest wine market since 2010. According to Wines & Vines total U.S. wine sales were $62.7 billion in 2017 and steady growth is expected.
Quick Guide: Planting, Growing & Harvesting Grapes
- Choose varieties best suited to your region
- Start from cuttings or nursery stock
- Plant in full sun in compost-rich soil
- Locate where breezes can dry off moisture
- Fertilize early in the season; water regularly
- Prune carefully to minimize side shoots
- Provide a trellis or other support
- Check regularly for pest damage, cover with netting to protect fruit from birds
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All types of grapes require a warm planting site with full sun and moderate water. Consult with a nursery professional to select a variety that will do well in your area. The soil at the planting site should be loose, rich and deep. The roots of grapevines go deep into the earth. Amend to a depth of 24 to 36 inches with a good organic compost or well-rotted animal manure to improve existing soil.
Pruning during the dormant season will control growth and produce abundant fruit, so keep reading for our recommendations.
Tip: To reduce the chance for disease, make sure breezes that can dry moisture from foliage are not obstructed by fences, shrubs or buildings.
How to Plant
Grape plants grow easily from cuttings. Select a healthy stem about 2 feet long with at least 4 buds. Place the cutting in fast draining, sandy soil in a location with full sun. Two buds should be below the ground and two above. The bottom half of the cutting should be dipped in rooting hormone. Early spring is the best time to plant from cuttings.
Plant from nursery stock by digging a hole as deep as the container. Prior to planting, soak the roots in compost tea for 20 minutes and dust roots with a mixture of 2 cups of kelp meal and 1 cup of bone meal. When planting, make sure that the top 1 inch of the root ball sits above the surface to prevent sucker growth from the graft. Space the plants 6 to 8 feet apart.
Water young vines for the first two years during the summer. Water deeply and infrequently to encourage strong, deep roots.
Provide support for mature grape vines in the form of a trellis or fence. Vines can be trained to cover arbors and gazebos.
Apply organic fertilizers rich in nitrogen two weeks after planting. Reapply annually in early spring right before growth starts. Do not apply nitrogen later in the season as it will delay ripening, inhibit coloring and create tender, late-season growth that will be damaged in the winter. Four to six inches of mulch may be applied to help control weeds and conserve soil moisture.
Tip: For a more productive harvest, plant grapes in raised beds or hills.
All grape varieties produce fruit on one-year-old wood. That means that the growth produced during the previous year will produce fruit for the coming season.
After planting, do no pruning at all during the first full year. Immature grapevines need abundant stems and leaves to help develop a strong root system.
The second year, select the strongest and most vigorous stem that developed during the first season. Remove all other stems and leaves as close to the base as possible. Stake the one remaining stem to provide support. This stem will become the main trunk of the vine. Pinch the top of the main stem to encourage side shoots.
After the second year, select two of the best-looking stems that are growing horizontally from the main trunk. Ideally they should be on opposite sides and about the same height on the trunk.
Remove all other side growth. By the end of the second year, you should have a plant that looks like a ‘T’. This is now the basic frame of the vine.
In following years, new shoots will form on the arms of the ‘T’. Leave 10 to 12 buds along each arm and remove all other growth along the main trunk. The buds will produce fruit, and every year thereafter should be pruned down to 1 or 2 new buds on each of twelve on the ‘T’.
- First year, no pruning.
- Second year, create a ‘T’.
- Third year, allow the top of each ‘T’ to form 12 buds.
- Fourth year +, prune the 12 buds down to 1 or 2 new buds during the dormant season.
Harvesting and Storage
Do not harvest grapes until ripe. Unlike tomatoes, they will not ripen further after harvest. Most varieties should be picked in bunches when all of the fruits in the cluster are fully colored, taste sweet and slide off easily. Other varieties, like muscadine berries, should be spot-picked because they do not ripen evenly.
Grapes taste best when used fresh. Can or freeze whole fruits or make jellies, jams and wine.
Insect & Disease Problems
Grapes are susceptible to a large number of insect and disease pests. Select disease-tolerant cultivars when possible and utilize good sanitation practices. Monitor vines closely and if problems occur, treat early with organic pest solutions.
Birds can be a major pest. The only sure method of protection is placing garden netting over the vines as soon as fruit begins to ripen.
Table grape growing, non commercial
Trellising and vine training
Vines can be trained over a pergola or a post-and-wire trellis. To begin this process, vines should be trained up a garden stake, bamboo stake or something similar. It is important during the first year to let the vine grow vigorously to achieve the desired height. This will allow the vine to establish a strong root system and framework (e.g. the trunk and arms of the vine). Only one single shoot should be trained throughout the first growing season; select two to three shoots initially, and remove all others. Tie the two to three shoots to the garden stake with string or plastic tape (flagging tape/budding tape). Once one of the shoots reaches 0.5-1.0 m in length, remove the other shoots, leaving the favoured shoot. Remove the lateral shoots that emerge at the base of each leaf. Do not remove the leaves during the growing season, these leaves will supply the vine with the food they require for the next growing season.
If the vines fail to reach the desired height in the first year, the shoot (now redish-brown in colour and called a mature cane) should be cut back in winter, to two to four buds above the beginning of it’s growth point. Repeat this training process again in the second year. If the vine establishes well in the first year, it will start producing bunches in the second year. A couple of bunches can be left to ripen if desired. We don’t want to overload (stress) the young vine with fruit at this stage of it’s life, as this will stunt it’s growth for future years.
Young grape vine on post and wires.
Watering and fertilising
Watering regimes will vary depending on where you are growing your vines. For the Perth region, regular watering of vines in the home garden is necessary from early November to late March in most seasons. Applying mulch will help retain moisture in the soil during summer months. Mulch can be placed all around and touching the trunk without risk of encouraging disease. Disease risk is minimised if the water can be kept off the foliage.
A mature vine will require about 500g of NPK fertiliser with trace elements each season. This should be applied as a 350g dressing at or near the start of budburst and a 150g dressing four weeks later.
There are two basic methods of pruning table grapes, these are spur pruning and cane pruning. If you are in the Perth region, pruning is best carried out in late August, however pruning can be done anytime after the leaves have turned yellow or the leaves have fallen. In regions where the temperature is not cold enough to induce leaf fall (e.g. the Gascoyne), vines should be pruned mid July.
Spur pruning is used on highly fruitful varieties such as flame seedless, italia, muscat grodo and cardinal. These varieties produce one or two bunches on every shoot every year.
Cane pruning is used on low fruitful varieties such as sultana, dawn seedless, red globe and crimson seedless. These varieties only carry bunches on less than half the shoots that emerge after pruning. If the name of the variety of grape is unknown, the best pruning method is to have a combination of spurs and canes until the fruitfulness of the vine can be determined.
*Photo of spur pruning*
Highly fruitful varieties that can be spur pruned only have bunches in the first 2-4 buds on each cane. How many spurs that will be left after pruning will depend on whether the vine is on a pergola or a post and wire trellis. If the vine is growing on a pergola, then 20-40 spurs can be left. If the vine is on a post and wire trellis then 16-20 spurs will be sufficient.
These spurs are shortened lengths of the previous season’s shoot growth and should be spaced 10–20cm apart on the permanent arms of the vine. Each spur should be two or three buds long which will produce a maximum of two new shoots in the spring.
The most common fault with pruning vines in the home garden is overcrowding of spurs.
*photo of cane pruning*
Varieties that need to be cane pruned carry bunches on the previous season’s growth towards the end of the cane. There are very few bunches to be found in the first four buds along each cane. These varieties require 6 to 12 canes at the end of pruning. Each cane will have 8 to 16 buds, but be no longer than 75cm. These canes are tied onto the wires of the trellis for support.