What kind of fertiliser do grapes require?

Answer 1

The fertilizer recommendations I've seen vary. One reference says a general purpose fertilizer will do. An old Encyclopedia of Organic Gardening says that potassium is especially important and you should apply 2 to 3 pounds of finely ground granite rock to the soil around a vine in the fall. Roots go out 3 to 6 feet from the base so spread out the rock. But where the heck are you going to find finely ground granite rock? To get potassium into the plant I've been using spray on kelp rated at 1-0-4. They say nitrogen is important too but phosphorus is not.

Grapes often get mildew (white powder) on the leaves or suffer from other fungus diseases. Problems like these can be minimized by growing the grapes in a very sunny area with lots of air circulation. Then there are varieties that are immune to these diseases and others that are only resistant, choose your variety carefully especially if you want to avoid spraying. If you have to spray the standard spray to use is Bordeaux spray, a mixture of copper sulfate and lime. These chemicals are safe in the sense that VERY small amounts of them inside your body will probably not do any kind of obvious damage. (Copper comes in Certs for instance, sulfate comes in glucosamine sulfate (said to cure osteo-arthritis), calcium (from lime) is just plain good for building strong bones.) On the other hand, copper sulfate is an acid salt, a solution of it is pretty much like sulfuric acid, the acid found in a car battery and it can cause burns. So you must be careful not to get any of it in your eyes, lungs, mouth, into cuts, into children or pets, etc., etc.. More than likely it would cause metal to corrode as well. The spray can be applied dry or dissolved in water.

Fertilizer for Grapes

Prior to planting is the only time elements such as phosphorus, boron and lime can be effectively worked into the soil. Nutrient levels in the topsoil considered to be adequate for vineyard establishment are 12-20 ppm phosphorus, 120-150 ppm potassium, 100-250 ppm magnesium, and 1,000-5,000 ppm calcium.

If the soil has been properly prepared, including deep cultivation and addition of organic matter, there should be an adequate supply of other nutrients to sustain the vine in the juvenile years. On coarse-textured, infertile soils, the use of a starter solution at planting time (e.g., 10-52-10 or 20-20-20) may give the vines a needed boost. High nitrogen levels can result in excessive growth and incomplete vine hardening. The use of cover crops to check late season growth in cultivated vineyards is strongly recommended, especially in new plantings. Cover crops such as Italian ryegrass, sown about July 1, will take up much of the available nitrogen in the soil and in this way have the desirable effect of checking vine growth.


Nitrogen (N)
Petiole analysis is the most accurate way to determine nitrogen requirements of grapes. In the absence of such information, 34 kg N/ha is usually sufficient for most cultivars. This nitrogen is best broadcast before the 1st cultivation or applied as early as possible in the spring in sod vineyards. Nitrogen application can be reduced or eliminated if manure is used or growth has been excessive. Foliar applications of nitrogen should be considered in some years, based on vine performance and petiole analysis.

If, because of severe winter temperatures, there has been fruit bud damage, it may be necessary to split applications. Apply the 1st application in mid-Apr. and the 2nd application, if necessary, after bloom in late May. Excessive spring rains can leach away spring applied nutrients. Apply additional fertilizer or foliar sprays after bloom. During dry springs, irrigation may be necessary to move the fertilizer into the rooting zone of the soil just before 1st bloom or immediately after petal fall.

Phosphorus (P)
Phosphorus is not required in large amounts by grapes. With few exceptions, the level of phosphorus in Ontario soils is presently adequate. Phosphorus does have a place for sod or cover crop maintenance. A soil test is the best way to determine if there is a need to apply this nutrient to the sod cover. In the absence of a soil test, a complete fertilizer (100 kg/ha 10-20-20) could be broadcast and incorporated before seeding a cover crop in a vineyard. Apply phosphorus before planting a vineyard, when it can be thoroughly incorporated in the soil if a soil test indicates a need. Phosphorus soil test values between 12-20 ppm are considered adequate for vineyard establishment and production

Potassium (K)
An excess amount of potassium can lead to deficiency of magnesium (Mg); avoid unnecessary potassium applications. Grapes require a larger quantity of potassium than tree fruits. In the absence of petiole analysis, 400 kg/ha of muriate of potash (0-0-60) every 2nd year on clay soil and 200 kg/ha every year on sandy soil may be adequate.

In cultivated vineyards, broadcast potassium before the 1st cultivation in the spring. With grapes on clay soils, apply potassium in a band to reduce potassium fixation in the soil. Potash can injure roots and trunks if applied too closely to the trunk.

Foliar application of potassium for grapes
In dry growing seasons potassium is not readily available to the plant. Where a potassium deficiency has been confirmed, foliar applications of potassium may be beneficial. Foliar potassium applied at veraison may improve fruit yield and quality.

Magnesium (Mg)
Magnesium deficiency is becoming more evident in vineyards, particularly when high rates of potash are used.

Magnesium deficiency can lead to premature fruit drop at harvest. Magnesium deficient vines have older leaves that are pale in colour, as magnesium is a part of the chlorophyll molecule. Petiole analysis is the best way to evaluate magnesium levels.

Foliar sprays of magnesium have been effective in correcting this deficiency for the current year only. For more permanent correction, soil applications of magnesium may be required. Magnesium soil test values between 100-250 ppm are considered adequate for grapes.

Fruit or foliage injury is possible from a mixture of pesticides with magnesium sulfate. It is best to apply magnesium sulfate separately or try it on a few plants first. Check manufacturer's label regarding mixing magnesium chelates with pesticides.

For long-term corrections, soil application of magnesium can be made. The response will not likely be immediate. Also, on some soil types a single, early-spring application of soil applied magnesium has not worked well. A 2nd or 3rd application the following spring may be required before the magnesium level in the plant improves. Foliar sprays are recommended for the first 2 yr, in addition to soil applications.

Dolomitic limestone can be used on acidic soils to raise the soil pH and to supply magnesium.

Calcium (Ca)
Calcium deficiency has been associated with stem and bunch breakdown of Canada Muscat and Himrod grapes. Some formulations of calcium chloride (CaCl2) have resulted in poor fruit finish if applied too close to harvest. Calcium sprays must contact the fruit for uptake to be effective. Apply adequate water volume to wet the entire vine. The more calcium applied, the better the control; but high concentrations can cause foliar burning. Use CaCl2 (77% flakes) at 4 kg/1,000 L of water from early July to mid Aug. Apply 3 sprays, 10-12 days apart. Do not apply calcium formulations containing nitrogen after the end of July or fruit quality may suffer.

For all the formulations, be sure to consult label directions for concentrations to use and for compatibility with pesticides. The product used is not as important as the total amount of actual (elemental) calcium applied. For example, calcium chloride (77% flakes) contains 28% actual calcium. For acceptable results up to 12 kg/ha of actual calcium is often required in a total of 4, or more, sprays. Calcium sprays may damage foliage and fruit if applied during low temperatures and wet weather. These conditions delay the drying of the spray. Injury can also occur if calcium is applied in hot (over 25 C) or humid weather.

| Top of Page |
Micronutrients for Grapes

Deficiencies of micronutrients or trace elements are not widespread in Ontario plantings. The desirable range for micronutrients is quite narrow. More damage is possible if micronutrients are applied in excess rather than from deficiencies. For this reason, do not apply micronutrients to fruit crops unless leaf analysis or visible symptoms confirm a deficiency. Only apply the nutrient that is deficient and in sufficient quantities to correct the problem.

Boron (B)
Boron deficiency is perhaps the most common of micronutrient deficiencies. It occurs mainly on alkaline soils (pH greater than 6.5), acid soils (pH 3.5-4.5), dry soils, soils low in organic matter, or on sandy knolls. Boron deficiency can have an effect on growth and fruiting. There is currently no accredited soil test for boron in Ontario. Use a petiole analysis to check for boron deficiencies. Boron levels should be 20-60 ppm. Where a boron deficiency has been confirmed, soil or foliar applications of boron may improve boron in plant tissues. There are several sources of boron. Check the manufacturer's recommended rates and timing of applications..

Answer 2

Use ammonium sulfate to fertilize your grape vines. The general recommendation is a half pound for each vine. You should apply the fertilizer when the grapes are at least a quarter-inch big.

You should keep in mind that too much nitrogen can result in more vine growth and fewer grapes. So, be conscious of the nitrogen content in any fertilizers you use on your grape vines.

Answer 3

grapes grow in very poor soil, and don't require fertilizer

Answer 4

depends on the type of soil

Answer 5

depends on the type of soil