Fruit trees are fertilized during the fall or winter to ensure proper absorption before temperatures fall below 50 degrees F. Fruit trees typically enter rest periods during the peak of winter months and cannot absorb nutrients during this time, notes Martha Proctor from University of California Marin Master Gardeners.
Fruit trees thrive best when treated with slow-release fertilizers that are 1/2 water soluble and 1/2 water insoluble. The trees are sensitive to nitrogen, and slow-release formulas allow for optimal absorption without shocking the roots. Fruit trees are typically sprayed with zinc on an annual basis.
Natural fertilizers, such as compost or chicken manure, are ideal treatments for fruit trees. Gardeners must maintain balanced irrigation practices, as over-watering can lead to excessive growth and increase the trees' risk of developing disease.