Fertilizing Your Houseplants

Proper fertilizing can produce bigger blooms, better health and added longevity for your houseplants. We've collected a few tips to help you get the most of your houseplant fertilizing this winter:

Types of Fertilizer

Houseplant fertilizers come in a number of formulations. Some are wettable powders or concentrated liquids that are diluted with water then applied to the potted plant. Time release fertilizers are available as coated pellets or as spikes. A few are sold premixed and applied directly to the potting soil.

The label on a fertilizer container states the guaranteed analysis or grade. These are the three numbers listed on the package (i.e. 8-7-6). They refer to the percentage of nitrogen, available phosphorus and water soluble potassium contained in the fertilizer. Plants require large amounts of these three nutrients and they are often referred to as primary nutrients or macronutrients.

Choosing a Fertilizer

Which is the best houseplant fertilizer for you to use? This will depend on the types of plants being grown, cultural conditions and your schedule. In general, foliage houseplants appreciate fertilizers high in nitrogen while flowering plants respond best to those with higher phosphorus analysis.

Purchase a water-soluble powder or liquid concentrate if plants are to be fertilized on a weekly, biweekly or monthly basis. If there will be long intervals between fertilizer applications, select time release formulations in either pelleted or spike forms.

When to Fertilize

The labels on most water-soluble fertilizers recommend monthly applications. Since these nutrients are easily leached from the potting mix, your plants may benefit from more frequent diluted applications. If one teaspoon per quart of water is recommended for monthly feedings, you could feed bimonthly using only one-half a teaspoon per quart or weekly using a quarter teaspoon per quart. This gives the plant a steady, continuous supply of nutrients. This type of regime is often recommended for flowering plants like African violets.

When fertilizing houseplants, always follow the directions on the label. More is not better and excess nutrients can harm roots and leaves. Always apply fertilizer to an already moist potting soil to avoid root damage.