Fertilize hardy fruit trees, such as apple, peach, pear and plum, and fruit bushes, such as blackberry and blueberry, during the month of February. Use a general purpose fertilizer or a fruit tree fertilizer and follow label directions.
For blueberries, use an acid-loving plant fertilizer. Hardy fruit trees should be pruned now.
Keep beds mulched to a depth of 2 to 3 inches to control cool-season weeds. Use leaves, pine straw, or other available materials.
If you miss the moment and the trees have begun to bloom, you can still fertilize until June.
Don’t fertilize in late summer or fall, though, because the new growth put on by the tree can be damaged by frost.
Most trees get a fertilizer with a 4-1-1 ratio of nitrogen, phosphorus, potash. But giving that much nitrogen to a fruit tree will encourage it to put out a tremendous flush of vegetative growth with very few flowers and not much fruit.
A low nitrogen 1-1-1 or 1-2-1 ratio is better. Ideally, the nitrogen component should be half water insoluble, or slow release, and half water soluble. Water-insoluble nitrogen breaks down slowly and feeds the tree over a period of months. Compost or horse and chicken manure are great slow release fertilizers. Water-soluble nitrogen breaks down all at once when it comes in contact with water and gives the tree a quick spurt.
The Roles of Different Fertilizer Ingredients
Nitrogen (N) is the nutrient most frequently found deficient in plants. The symptoms of nitrogen deficiency are:
- Foliage lighter green in color
- Poor growth
- Smaller leaves
Potassium (K) is mobile and needed in many reactions in the plant. Except for sands, most mineral soils are originally high in total K. The symptoms of potassium deficiency are:
- Restricted growth
- Shoots die back in extreme cases
- Leaves in the middle of the shoot area are affected, not basal leaves or shoot tips
- Leaf margins and/or areas between veins may scorch
- Interveinal chlorosis
- Fruits tend to be smaller; fruit may shrivel when deficiency is severe
- Leaf curling or cupping may be present
Phosphorous (P) deficiency is not often found except on red foothill and mountain soils. Available P comes from the breakdown of soil minerals or organic matter, and it is quite mobile in plants. Foliage of deciduous or evergreen trees deficient in P becomes dull and bronzed (even purplish) in late summer.