Growing Grapes (Vitis vinifera) have the reputation of being fragile and difficult to cultivate. Growing grapes in your backyard are not that difficult as some assume it to be. One of the best things about growing grapes is their adaptability to varied climate and soil.
Another important thing to know when growing grapes is knowing when and how to fertilize the soil for enhanced growth. The best fertilizer for grapevines should be rich in macro and microelements. Once established, a well-tended plant can be productive for 40 years or more.
Pre-planting Fertilization of Grapevines
Grapes (Vitis vinifera) planted in most soil types require some fertilizer to grow their best. Excessive soil nutrients, however, cause vines to grow rapidly while fruit production and quality decrease. Different types of nutrients should be applied to grapes throughout the growing season.
If a soil test reveals rich soil, you might want to err on the lighter side when it comes to fertilizer applications. Grapevines will generally require more nutrients as they mature. If the results of your test show the soil pH is fine but magnesium is lacking, add 1 pound (0.5 kg.) of Epsom salts for every 100 square feet (9.3 square meters).
Should you find your soil is lacking in phosphorus, apply triple phosphate (0-45-0) in the amount of ½ pound (0.22 kg.), superphosphate (0-20-0) at the rate of ¼ pound (0.11 kg.) or bone meal (1-11-1) in the amount of 2 ¼ pounds (1 kg.) per 100 square feet (9.3 square meters). Lastly, if the soil is low in potassium, add ¾ pound (0.34 kg.) of potassium sulfate or 10 pounds (4.5 kg.) of greensand.
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 a 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. For a more productive harvest, plant grapes in raised beds or hills.
When to Feed Grapevines
Grapes are deep-rooted and, as such, require little additional grapevine fertilizer. Unless your soil is extremely poor, be cautious, 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 (0.11 kg.) of 10-10-10 fertilizer in a circle around the plant, 4 feet (1.2 m.) away from each vine. In successive years, apply 1 pound (0.45 kg.) about 8 feet (2.4 m.) from the base of 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.
Grapevines Nitrogen Requirement and Application
Grapevines require nitrogen when they grow rapidly during the spring. If you want to fertilize grapes using manure, the University of California recommends applying it in January or February. Apply 5 to 10 pounds of poultry or rabbit manure or 5 to 20 pounds of a steer or cow manure per vine.
Other nitrogen fertilizers, such as urea, ammonium nitrate, and ammonium sulfate, should be applied after bloom or when the grapes reach 1/4-inch in diameter. You can apply 1/2-pound of ammonium sulfate, 3/8-pound of ammonium nitrate or 1/4-pound of urea per vine.
Grapevines Zinc Requirement and Application
Zinc helps grapevines with pollination, hormone production, and other essential plant functions. Signs of zinc deficiency include stunted shoots and leaves, as well as reduced fruit set. The best time to apply zinc is during spring about a week before they bloom or when the vines are in full bloom.
A zinc spray with a concentration of 0.1 pounds per gallon should be applied to the foliage of each vine. Alternatively, pruning cuts can be dipped into a zinc solution immediately after pruning vines during early winter.
Grapevines Potassium Requirement and Application
If grapevines show signs of a potassium deficiency, such as decreased shoot growth, chlorosis (yellowing), and burning during summer. Potassium fertilizer should be applied during the spring or early summer when the vines are beginning to produce fruit.
You may also want to apply potassium if soil tests reveal a deficiency. Experts at the University of California recommend applying 3 pounds of potassium sulfate per vine for a mild deficiency. For a severe potassium deficiency, up to 6 pounds per vine should be applied.
Tips on Planting, Growing & Harvesting Grapes
Planting and management of grapes have some requirements that need to be satisfied. Below are tips to assist you to plant grapes successfully.
- Varieties best suited to your region should be selected.
- Start from cuttings or nursery stock
- Plant in full sun in compost-rich soil
- Locate where breezes can dry off moisture
- The plant must be fertilized early in the season and be watered regularly
- The plant must be pruned carefully to minimize side shoots
- A trellis or other support should be provided.
Site Preparation for Grapes
All types of grapes require a warm planting site with full sun and moderate water. An area that has adequate sun, a soil with a pH of 5 – 6.5, well-drained but not soaked with enough nutrients to grow just well must be chosen.
Too much fertilizing can make them grow fast but they will not bear grapes that well. So, make sure you do not fertilize your grapevines more than necessary. The soil at the planting site should be loose, rich, and deep.
The roots of grapevines grow deep into the earth. Amend to a depth of 24 to 36 inches with good organic compost or well-rotted animal manure to improve existing soil. Pruning during the dormant season will control growth and produce abundant fruit.