When to Fertilize a Tree:
Again, for young trees, the time to put out fertilizer is late March through early June. When a tree reaches the desired height you may want to decrease the fertilizer application to only once a year.
How to Fertilize a Tree:
An application of between .10 and .20 pounds of nitrogen per 100 sq. ft. will be adequate.
Again, read the lable. Keep solid or concentrated fertilizer off stems and leaves and adequately water the fertilizer into the soil as that prevents fertilizer burn injury to roots. Stick with the higher ratio nitrogen fertilizers unless your tree is determined to be deficient in potassium or phosphorus (soil test). N-P-K rates of 18-5-9, 27-3-3, or 16-4-8 are good bets.
Organic ferilizers are harder to find than inorganic fertilizers and often more expensive but they are the least harmful and less exacting when applying. The best organic fertilizers are cottonseed meal, bone meal, manure and chicken litter. Read the label (if packaged) for application methods and amounts to use.
General purpose fertilizers are complete with N-P-K which is usually defined as the ratio of nitrogen, phosphorus and potassium in the mixture. You can use these excellent fertilizers but don't overdo. Use high-ratio nitrogen products unless a soil test suggests a lack of other nutrients. Inorganic fertilizers can come in slow-release, liquid or water-soluble for foliar application.
Read the label for application rates.
Remember Organic Soil Amendments:
Peat moss, leaf mold, pine bark, sawdust, and stable manure can improve the soil while adding nutrients. These amendments increase the fertilizer and water-holding capacity of many soils. Mulching with these amendments aid in root development.