New growth should not exceed 2 feet in length annually. Nitrogen is the most important nutrient in fruit production and is usually the only fertilizer element that should be applied regularly in Michigan. As the trees become older, start producing and the danger of winter injury becomes less, nitrogen applications will need to be increased sufficiently to insure an annual terminal growth of 16 to 24 inches to maintain good production. Apply nitrogen in late fall, after mid-November, or before growth starts in spring. Potassium is the only nutrient element, other than nitrogen, that is likely to be needed in Michigan apricot plantings.
Potassium deficiency reduces tree growth, yields and fruit quality.
When needed, potash may be applied in the fall or spring. Phosphorus is utilized in only small amounts by fruit trees compared to either nitrogen or potassium. There is no present indication that apricot trees will benefit from application of phosphorus. However, in some cases, fertilizers containing phosphorus may benefit growth of cover crop. Otherwise, fruits will be small, and the trees will become biennial in bearing habit.