How To Fertilize Your Houseplants

Fertilizing

Newly purchased plants have been well fertilized in the greenhouse. They seldom need additional fertilizer for a few weeks. If plants are to be discarded after flowering, there will be no benefit from fertilizing. Plants to be kept on in the home should be put on a regular fertilization program.

When to fertilize
Fertilizing once a month is usually adequate for most houseplants that are producing new growth or flowers. During midwinter (December, January) when no new growth is apparent, fertilizer should be withheld.

Do not use fertilizer to stimulate new growth on a plant located in poor growing conditions. Lack of growth is more often due to improper light or watering than to nutritional deficiencies. In such cases adding fertilizer may actually cause additional injury.

Drop of lower leaves, overall yellow-green color or weak growth may indicate a need for fertilization. Since these same symptoms may result from poor light or overwatering, evaluate all conditions before fertilizing more than normal.

Kind of fertilizers
Water soluble, complete fertilizers have been formulated for houseplants and are available from many garden shops, florists and nurseries. They are easy to use. Since formulations vary, be sure to follow directions carefully. Do not apply more than directed. The roots of potted plants are quite restricted and easily burned by the application of too much fertilizer at one time.

Never apply liquid fertilizers to wilted plants. Water the plants first and apply fertilizer after the plants have recovered and the soil has dried slightly.

If soluble fertilizers such as 20-20-20 are available, these may also be used for fertilizing houseplants. Make a solution by mixing 1-1/2 teaspoons of this material in one gallon of water.

Some people prefer to use organic fertilizers for houseplants, but either organic or inorganic fertilizers or a combination of both will be satisfactory sources of nutrients.

Fertilizers that release nutrients slowly or over a long time period require less frequent application than liquid forms. They are available in beads, pills, spikes and other forms. Never exceed amounts suggested by the manufacturer's directions.

Which Fertilizer to use

A commercially available fertilizer is recommended. Specially labeled fertilizers for houseplants work well. A good ratio to choose is a 1:2:1, such as 5-10-5 or 10-20-10. Also a balanced ratio is good, such as 10-10-10. Follow the directions on the label. Never use a stronger mixture than what is recommended.

Fertilizers may be liquid, powder or tablet. Also, slow-release forms can be mixed into the potting soil at planting time or applied to the surface. Most last 3-4 months.

To help avoid a salt buildup in the soil, leach the pot every 4-6 months. Pour a large volume of plain water into the pot and allow it to drain through completely. Empty the saucer.

Important Note

Take care not to over-fertilize your plants. Plants should be fertilized only when they are actively growing.

Most houseplants will not need to be fertilized more than once every 1 – 3 months, between March and September. During the short days of winter, plants experience a rest period and usually need very little or no additional fertilizer. This schedule is sufficient to maintain their health.

If you fertilize more frequently, the plants may outgrow their pots and space too soon. Also, plants may be damaged with too much fertilizer, especially when their growth rate is slowed in dim light. Too much fertilizer can burn roots.