The most important food for plants is water, sunlight and carbon dioxide. About 94% of plant dry weight consists of carbon, hydrogen and oxygen, derived from the process of photosynthesis. The remaining 6% is composed of 13 essential mineral elements, the largest portion of which is nitrogen, phosphorus, and potassium. All these mineral nutrients are important for plant growth, they cannot make up for insufficient water or sunlight.
Spring is the best time to apply fertilizer to fruit crops except for strawberries. If the site was well prepared prior to planting, and if the soil contains some organic matter, fruit plants generally only require an annual application of nitrogen fertilizer. Before planting perennial fruit crops, amend the soil with organic matter and add some complete fertilizer that contains nitrogen, phosphorus, and potassium. Spray or till the organic matter and fertilizer into the soil before planting.
Fruit trees require about an ounce of actual nitrogen per year of tree age up to about eight ounces of nitrogen per tree per year. Another way to gauge the amount of nitrogen required is to see the amount of new growth produced by the trees. Young trees that are not yet producing fruit should grow 12 to 18 inches of new growth per year. Berrying trees should produce eight to 12 inches of new growth per year. If growth is less than this, they would benefit from additional nitrogen. If growth is more than this, then reduce the application of nitrogen by half.
Strawberries should not be fertilized in the spring. The best time to fertilize strawberries is in the summer, just after the fruit are harvested.
Applications of micronutrients usually is not necessary for fruit crops. One exception, however, is iron, especially for peaches. Fertilizer won't make up for other poor management, but fertilizer is important to get the best growth from our plants.
