Cherry trees are famous for their delicate pink blossoms that contrast with their dark, twisted branches. They provide backyard shade and the first crop of tree fruit of the season, but they must be properly cared for to perform optimally.
According to the British Columbia Ministry of Agriculture and Lands (BCMAL), cherry trees do not require fertilizer for the first two years if you keep weeds in check and soil nutrients are balanced. Heavy mulch around the base of the tree protects and nurtures the soil, keeping the roots moist and cool.
Until your cherry trees bloom, fertilize in spring. Trees growing in good soils will need only nitrogen fertilizers. Once trees begin bearing, however, the National Gardening Association recommends waiting until after harvest, and applying nitrogen by midsummer, rather than in spring.
According to Purdue University Cooperative Extension Service's (PUCES) Department of Horticulture, a mature cherry tree should receive about one tenth of a pound of actual nitrogen per year of the trees age, up to one pound. The exact quantity depends upon the concentration of nitrogen in your ammonium nitrate fertilizer; check the label for the percentage. Apply the fertilizer around the base of the trunk about 12 inches away, and extend the band to the edge of the branches.
The PUCES indicates cherry-growing success with occasional applications of both nitrogen and potassium, unless the soil is phosphorus-deficient. If a soil sample indicates low phosphorus, use a fertilizer containing 12 percent nitrogen, phosphorus and potassium (12-12-12), otherwise use a fertilizer with 15 percent nitrogen and potassium (15-0-15).