Peach trees (Prunus persica) like other fruit trees require a careful balance of nitrogen and other minerals to ensure the proper growth of foliage without sacrificing fruit growth. At certain times of the tree's growth, a straight nitrogen fertilizer like ammonium nitrate is needed instead of using a balanced fertilizer. Peach trees are hardy in U.S. Department of Agriculture plant hardiness zones 5 through 9.
About Ammonium Nitrate
A number of nitrogen-only fertilizers are available, and ammonium nitrate is one of them. The numbers on packages of fertilizer give you the percentages by weight of nitrogen, phosphorous and potassium. Packages of ammonium nitrate bear the numbers 33-0-0 because this material offers 33 percent nitrogen by weight. When using ammonium nitrate, check the pH level of your soil regularly, because frequent use of this type of fertilizer will lower the soil's pH. Peaches grow best in slightly acidic soil with a pH between 6.0 and 6.5. If you experience problems with the pH lowering too much by using ammonium nitrate around your peach trees, neutralize the effects by adding 3 pounds of limestone to the soil for every pound of ammonium nitrate you use.
Fertilizing your peach trees supplements the nutrients that may not be inherent in the soil. In some locations, potassium or phosphorous is needed because the soil lacks this nutrient, but nitrogen is usually needed for growing plants to help the plant grow foliage. To apply the fertilizer, spread it directly on top of the ground and water it in to ensure all of the nitrogen reaches the soil instead of being lost to the air. Keep the fertilizer at least 1 foot away from the trunk of the tree to prevent burning the bark.
Amount to Use
The amount of ammonium nitrate used for peach trees depends on the tree's size and age. For newly planted peach trees, a total of 1 cup of ammonium nitrate is needed, but this increases to 1-1/2 cups for the second year. Mature peach trees will need an average of 3 pounds of ammonium nitrate distributed at intervals throughout the growing season.
The fertilization frequency is determined by dividing total amount of fertilizer needed over the course of the year by the number of times you fertilize. Start in the spring, around the first of April, with the first application. Young trees in their pre-bearing years should have monthly fertilizer applications, but older trees can be fertilized three times a year. Mature trees should have fertilizer applied in the spring, summer and just after harvest in the late summer or autumn.
Fine Tuning Fertilization
Adjust your fertilization schedule or amounts if you notice signs of nitrogen deficiency or excess. Too much nitrogen prevents the tree from producing fruits because its growth is concentrated on growing large leaves. If the leaves on your peach tree look pale green or yellow with red margins and have stunted growth, you may need to increase the amount of fertilizer you use to resolve this nitrogen deficiency.
- University of California Davis Cooperative Extension: Fertilizing Temperate Tree Fruit and Nut Crops at Home
- University of Georgia College of Agricultural and Environmental Sciences: Peach Orchard Establishment and Young Tree Care
- University of California Davis Cooperative Extension: The California Backyard Orchard: Peach (Prunus Persica)
- Harvest to Table: How to Grow Peaches
- Penn State University Extension: Nitrogen Fertilizers
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