Home Gardening

Troubleshooting houseplant pest problems
The Coast Gardener Newspaper and Web Column - March 23, 2002

Even the best gardeners will have indoor plants that do not perform well. Cultural and environmental factors play a big part in the overall success of your indoor gardening efforts. Sometimes, however, insects and diseases can take their toll on your houseplants, too.

As I discussed last week, the two main reasons gardeners fail with houseplants is failure to provide proper levels of water and light. Either too much or too little of each can harm your plants; this depends largely on each plants' water and lighting needs. Not all plants like the same conditions.

Abnormal foliage color can be associated with low light, overwatering, insect or disease pressure, or lack of nutrients. When the very tips of the leaf margins (edges) turn brown, this can be associated with overwatering, exposure to cold, or too much fertilizer. Too much fertilizer causes a buildup of salts that will burn the tips of the leaves. When salt levels are high, you can sometimes see a white ring around the pot. Flushing the soil with plenty of water will usually correct the problem.

Spotted or discolored leaves may indicate root rot from too much water or burn from too much sunlight. Sometimes diseases can cause leaf discoloration, too.

Have you ever noticed your houseplants suddenly dropping all their leaves? This common problem can be associated with water stress caused by too much or too little water. Other times leaves will drop due to transplant shock or a sudden change in light intensity. This can be a common problem when plants that have enjoyed the outdoors all season long are brought indoors for the winter months. Gradual acclimation from higher to lower light conditions is important to lessen this shock and help decrease leaf drop. Cold drafts can also cause leaves to fall off.

Most houseplants that are supposed to bloom need the proper light intensity levels to do so. Sometimes, however, houseplants that fail to bloom may be undernourished or kept in areas that are too warm or too cold.

Botrytis blight, powdery mildew, and root rot are a few common diseases that plague houseplants. Prevention is the best method of control. Provide proper cultural and environmental conditions to lessen the occurrence of these diseases.

Spider mites, cyclamen mites, and mealybugs are common insect pests of houseplants. Several houseplant insecticides are available. Particularly useful on houseplants is insecticidal soap that kills soft-bodies insects quite well. With severe insect infestations, a more potent insecticide may be required. Whatever you choose to use, read and follow label directions carefully.

Remember, it isn't always an easy task to grow plants indoors. Always research your houseplants of choice and learn what makes them happy, because happy houseplants add a bit of coziness and warmth to any décor.

These archived gardening columns were written by Chance McDavid, former Harrison County Extension Agent.