The methods of fertilizing interior plants is quite varied. Some people prefer one of the many slow release fertilizers currently available. The "life" of these types of fertilizers may vary from two to three months to a year and a half, depending on the type selected. The difficulty with these type of fertilizers is in determining when it should be reapplied. Temperature, frequency of watering, and growing conditions affect how rapidly these slow-release fertilizers are depleted. For this reason, many fertilize interior plants with a water-soluble fer tilizer such as 20-20-20.
If a water soluble fertilizer such as 20-20-20 is used, a diluted solution is ap plied once every two weeks during the summer and once a month during winter when the plant is less actively growing. The solution may be made by mixing one teaspoon of 20-20-20 in each gallon of irrigation water solution.
An alternative fertilizer program is to use one-fourth teaspoon of the water soluble fertilizer per gallon of irrigation water solution. This may be applied at each irrigation. With either method, make sure that some drains out of the bot tom of the pot. This will help prevent the build-up of fertilizer residue and pos sible root injury.