Gardening Help FAQs



Horticulture Questions and Answers

When and how should I fertilize my indoor plants?

How much and how often to fertilize an indoor plant depends on the plant, the season, and the environment. An actively-growing plant in bright light in midsummer may need fertilizing weekly. A mature plant that is spending the winter indoors under low light conditions may need no fertilizer from fall to spring.

When a new plant arrives in your home, do not fertilize it immediately. The sudden change in environment is a shock, it may not grow for a few weeks, it may even lose some leaves. When it shows new growth, you may begin to fertilize, lightly at first.

When foliage begins to turn yellow, one's first thought may be to fertilize. Wait! The problem may be cold temperatures, insufficient light, too much fertilizer, or the plant may be going dormant naturally.

If you suspect a problem, remove the soil-root ball from the pot and examine the roots. Solid, firm roots, red, brown or white, suggest good health, and possibly fertilizer will help. If the roots are soft, mushy, or black, the problem may be over watering, excess fertilizer, or toxic salts. If salts are found, return the soil ball to the pot and pour lots of water through the pot, letting the water drain through the pot, to wash out the fertilizer or salts. Then keep the plant drier than usual for several weeks.

A general lightening in color of the foliage and the production of smaller leaves may indicate the need to start fertilizing. Feed regularly when plants are actively growing. This is generally late spring, summer, and early fall. How bright the light is plays an important role with indoor plants. The brighter the light, and the faster the plant is growing, the more fertilizer it needs. Tropical plants under low-light conditions should not be stimulated with fertilizer in the winter. The fertilizer may encourage new growth that will be leggy or otherwise unsatisfactory.

The type of soil mix also influences how often you must feed and water your plant. A light soil mix - containing lots of peat moss, vermiculite, or perlite - needs water and fertilizer more often. A mixture containing garden soil needs them less often.

There are several ways to fertilize indoor plants. Slow release fertilizers are easy to use but expensive. You can buy tablets or small granules to spread on the soil surface, following the manufacturer's directions. Liquid fertilizers are also satisfactory. Generic dry granules, as 12-12-12, are very satisfactory and the cheapest. Whatever the fertilizer, do not let it touch the foliage and water it in well after application.