Fertilizing Indoor Plants
Date: April 1989 (Revised June1996)

Source: NDSU Extension Service Horticulturists

Do not feed most plants for the first three months after they arrive in your home. Northern grown plants often have sufficient nutrient supplies to last approximately two to three months.

It is always a temptation to feed plants when foliage begins to turn yellow. The real problem may be one of excess soluble salts or fertilizers in the soil. Water the soil heavily to remove toxic salts. Using distilled water is which salt-free is most effective for this.

A general lightening in color of the foliage and production of a smaller sized leaf may indicate that you need to start a feeding program.

There are several ways to fertilize indoor plants. Slow release fertilizers are easy to use - you can buy tablets or small granules to spread on the soil surface. Follow the manufacturer's directions. These fertilizers generally last three to four months.

Liquid fertilizers are a second. The manufacturer may recommend the application of a small amount with each watering or larger amounts or longer watering intervals.

Feed indoor green plants regularly when they are actively growing. This generally coincides with late spring, summer and early fall months.

Apply fertilizers when the soil is moderately moist. You can easily injure the root system if you fertilize an overly dry soil ball.

The type of soil mix also influences how often you must feed/water your plants with these mixes. An increasing number of growers have turned to so called lite soil mixes. It is important for you to feed on a regular basis to sustain healthy foliage.

Look at the root systems to help guide your decision whether or not to fertilize indoor plants. Do not apply a fertilizer if the roots are not a healthy white.