Fertilizing Houseplants

Wild West District Blog Article

By Ron Honig

September 3, 2025

Fertilizing Houseplants

Properly fertilizing house plants can pose a challenge for some as the purpose is different from fertilizing a garden. Once grown to an adequate size, houseplants only need to be fertilized well enough to maintain a healthy foliage. Unlike a garden crop, a homeowner should not be looking for maximum foliage production from their houseplants, as long as the plant remains healthy and produces satisfactory flowering.

It is very easy to over-fertilize potted plants and thus have to take measures to remedy the build up of salts in the potting soil.

It is difficult to provide a specific fertilizing recommendation due to the fact that houseplants and their containers vary in size and plant type. Following are a few recommendations from several university horticulture experts on how to best fertilize your houseplants.

Less is Better

Follow the directions on the specific fertilizer product you are using, and if you are the type of person that tends to get carried away applying fertilizers, dilute the fertilizer in half to start with and only fertilize every second or third watering to prevent over fertilizing.

Extension Agent Debbie Dillion from North Carolina writes the following comments about fertilizing house plants. “People often say they are feeding their plants with plant food rather than fertilizing. One does not feed a plant when you fertilize. Plants make their own food in the process of photosynthesis. Fertilizer allows plants to make and utilize this food.”

Dillion adds, “Never fertilize a diseased, injured, or damaged plant. Fertilizer is not medicine. Wait for the plant to recover before encouraging it to put its energy reserve into new growth.”

Winter fertilizing

During the winter months, indoor plants don’t need fertilizer because reduced light and temperature result in reduced growth. Experts say fertilizing at this time could harm some plants. Only fertilize houseplants from March through September.

Over-Fertilizing

Excessive fertilizer results in the buildup of salts in the plant’s potting soil and can lead to unneeded, leggy growth. The white residue around the outside of old clay pots is fertilizer salt buildup. Plant roots near the accumulated fertilizer salt will likely be burned as will leaves or leaf petioles resting on the fertilizer salt residue at the edge of the pot.

Typical symptoms of fertilizer toxicity are browning or dieback of the leaf tips and margins. Other symptoms can include reduced growth, lower leaf drop, dead root tips, and wilting. Sometimes yellowing or stunting may occur.

Fertilizer salts may also accumulate on the surface of the potting media as a white crust, especially if bottom watered, and cause stem collapse at the soil line.

The best remedy for smaller pots is to repot the plant with fresh potting soil. For larger pots with good drainage holes, flushing the soil with clean water can carry out the salts with the draining water. Repeat this procedure several times with a volume of water at least that of the pot size.

Simple Fertilizers Work Fine

There are hundreds of fertilizer choices sold on the market today. Many are what we might call “Fancy Formulations” of nutrients in various forms. The thing to remember is, in the end all formulations break down into the same elements or combinations of elements that are actually used by the plant.

Consumers should look at the concentration percentage of the active ingredients in the fertilizer products and calculate the cost per unit of the nutrients it is supplying. Simple, basic fertilizer formulations are usually the most cost-effective products to purchase.