Most commonly, the ideal time to feed is in the spring after bud break when plants are in full leaf. During this time the vascular system is most active and able to uptake nutrients. By applying a slow release source (ureaform, UF, or SNT stabilized N) plants will have a consistent nitrogen availability over several weeks or months.
If feeding in the fall, nitrogen is not needed for uptake but is held by the root system as stored energy. Application rates therefore are lower in the fall.
There are times when fertilization is not recommended. If there is an infestation of sucking or scale insects, many of them benefit from nitrogen application and the infestation can increase. Control the pest first, then apply fertilizer to assist the plants is recovery. When to deep root feed trees and shrubs?
During drought situation refrain from fertilizing until plans are well irrigated and begin to recover. Then apply low amounts of fertilizer to aid in the recovery.
It is usually not advantageous to fertilize newly planted trees and shrubs the first season. If plants do show symptoms of needing fertilizer, use low rates.
After analyzing all the various fertilizer application situations, Doggett has the solutions to address the plants nutritional requirements. Find them here.