Although commercial vineyards produce the majority of grapes for wines, juices and jellies, many home gardeners enjoy growing and experimenting with various grape cultivars. These plants provide fruit for produce, but also enhance and add ornamental value to many landscape designs. Most grape plants require well-drained soils with adequate levels of nutrients. Increasing the health of the soil by adding nutrients to areas containing grape vines increases the fruit yield and encourages healthy and vigorous growth.
Test the soil near your grape vines in the fall to identify possible deficiencies requiring attention. Annual testing provides valuable information regarding the current health of the soil in your vineyard. Collect soil for your sample from the top 8 inches of soil. Avoid sampling soil from the middle or edges of the vineyard. Check the pH level on your test results. Grape vines require a pH level between 5.5 and 6.8 for optimum health.
Add magnesium to soils with a low pH level. This important nutrient may be deficient in soils with low pH readings. Look for symptoms of magnesium starvation by examining the leaves on your grape vines. Yellow sections on the leaves between green veins often indicate a magnesium deficiency. Increase the level of magnesium in your soil by adding dolomitic limestone. Follow the manufacturer's instructions when determining the proper rate of application for feeding this nutrient to your grape vines.
Add potash to soils with a high pH reading if other signs of potassium deficiencies appear in otherwise healthy specimens. Look for potassium deficiencies by examining the leaves of your grapevines towards the latter part of the summer. Leaves that appear bronze in color, or display dark spot and blotches may indicate this deficiency. Increase the level of potassium in the soil by applying a foliar spray containing potash. Mix 6 to 10 pounds of fertilizer per 100 gallons of water. Apply at a rate of 200 to 300 gallons per acre throughout your vineyard.
Apply nitrogen to the soil in your vineyard once each year. Nitrogen increases the stamina of the vines and the yield of fruit. Apply at approximately the same time the fruit begins to appear on the vine. Apply this nutrient at a rate of about 50 to 100 pounds per square acre of vineyard.