The First Year

• Do not fertilize a new orange tree until it begins growing at the beginning of the season. Use a total of one cup ammonium nitrate, split into three or four applications. Scatter the fertilizer at the base of the tree and water thoroughly.
  
  

Juvenile Tree

• For the second through fourth years of the tree's life, use the same early-season fertilizer scatter, but increase the total amount of ammonium sulfate by one cup per year.
  
  

The Mature Tree

• By the time the tree is about 5 years old, it will require fertilizing in February, May and September. Continue using a total of one additional cup of ammonium sulfate per year of the tree's age, simply scattering it around the base of the tree.
  
  

Mulching

• While mulch can nourish the soil of most plants, it is not recommended for citrus trees. If weather conditions require mulch to keep moisture in the soil, keep it at least 12 inches from the base of the tree.
  
  

Bonus Boost

• Some orange growers have found success using a weekly application of seaweed solution on the base of the tree in summer months. This gentle formula is organic, and provides a small influx of trace elements the tree may otherwise be missing.