Palm trees thrive when given a special palm tree fertilizer. Because indoor palm trees tend to be potassium deficient, this type of fertilizer has more potassium than the usual fertilizer given to other plants.
The best type of palm fertilizer is an 8-2-12 + 4 or 12-4-12 + 4 mix. This means that every 100 pounds of fertilizer has 8 or 12 pounds of nitrogen, 2 or 4 pounds of phosphorous, 12 pounds of potassium and 4 pounds of magnesium. The fertilizer also needs to have trace minerals such as manganese, zinc and copper, and it is better if the nitrogen, magnesium and potassium are the slow-release type.
A palm tree is best fertilized three times over the growing season.