With the added stress this year has brought many of us, and now the busyness of the holiday season, it is nice to turn to my houseplants for a moment of relaxation and enjoyment.

Houseplants add form, movement, texture, and life to indoor living areas. It is therapeutic to water and enjoy them while the weather is cold outside. As with outdoor plants, houseplants may have browning leaves due to under- and over-watering, low humidity, salt build-up from fertilizer, insects, and diseases.

When leaves begin to wilt or the edges turn brown, the first thought is the plant needs water. Before watering the plant, check the soil by feeling it with your finger. If the soil is dry, apply water. It is best to water a plant before it wilts to avoid injuring it.

On the other hand, if the soil is wet, wait before watering. Over-watering also causes wilting and brown leaves. If the plant’s roots cannot obtain oxygen in flooded potting soil, the plant will wilt.

Some plants like constantly moist soil while others need to go dry between waterings. Check each plant’s requirements to determine how dry the soil should be before watering again. Watering a plant a little each day causes the buildup of salts from fertilizer and results in poor root development.

The risk of over-watering plants can be reduced by growing them in containers with drainage holes, which allow excess water to flow out of the pot. Pour off excess water or fill a saucer with pebbles so the water collects in them and the pot is above the water.

You can also use an unglazed clay pot for a container; this dries out faster and helps reduce the risk of over-watering.

Pot-bound houseplants are more susceptible to brown leaf edges because the soil is filled with roots. This reduces the amount of water the soil can hold. Increase the frequency of watering, or repot into a container 1 or 2 inches larger in diameter.

A larger container and new soil mix will reduce the need for water. Check the soil to determine how often to water the newly transplanted houseplant.

Another reason leaves turn brown is due to a lack of humidity in the home, especially in the winter. Watch out for the drying effect of heated air that blows from the furnace in winter and air-conditioned air in summer. You may find it necessary to place plants on a moistened pebble tray or use an air humidifier or vaporizer to increase the humidity around your plants.

Over-fertilizing can also cause leaf browning. In general, fertilize plants every one to three months with a water-soluble fertilizer. Fertilize plants more often when they are growing rapidly or after they have been pruned.

Check the fertilizer label and needs of the plant to develop a schedule. A water-soluble, complete fertilizer containing nitrogen, phosphorus, and potassium is recommended for most houseplants.

If over-fertilizing is a problem, you can reduce further damage. White crusty salts on the soil or the pot result from excess fertilizer or hard water. Leach the soil to wash out excess fertilizer.

To do this, water the soil until the excess runs out the bottom of the container four times in one hour. Then water the plant as needed, and wait one to two weeks to see if this procedure has stopped further browning of the leaves.

Leaching will not only wash out excess fertilizer but will reduce damage. To help prevent a buildup of salts, avoid over-fertilizing and always water the plant thoroughly by letting water run out the bottom of the container.

Insect feeding may also cause brown leaves. They may have come in on the plants when they were brought in from outdoors. Check stems and undersides of leaves for signs of insects and sticky honeydew. The honeydew is produced by aphids, mealy bugs, and/or scale sucking sap from the plant.

Broadleaved plants can be washed with soapy water and a soft brush or cloth to remove or kill insects that stay on the plant constantly. Use one teaspoon of mild detergent or soap in a gallon of water.

Although this method is time consuming, it may be the best alternative to insecticide sprays, which could injure the plant. Repeat washing if the infestation reappears. A thorough washing often holds scale infestations at bay for several months.

Spider mites also cause leaf browning. These tiny insects make little webs when the population is high. Wash spider mites off plants with a tepid shower of water every three to four days.

Plant diseases are rarely a problem for houseplants but may cause brown spots, blotches, internal browning, or leaf-edge browning. Root- and stem-rotting diseases typically occur after plant roots are damaged by over-watering.

To help prevent problems with diseases, avoid wetting the foliage when watering, and use a well-drained soil mixture that has been sterilized. Also, allow air to circulate around the plant. Leaves with disease problems should be removed from the plant.

For more information about growing houseplants, contact the Daviess County Cooperative Extension Service at 270-685-8480 or annette.heisdorffer@uky.edu.

Annette’s Tip

Still looking for holiday gifts for your friends and family? Consider gardening books, a collection of seeds to plant in the spring, or a gift certificate for a garden center. If you have any questions, contact the Daviess County Extension Service Office at 270-685-8480 or annette.heisdorffer@uky.edu.

Annette Meyer Heisdorffer is the Daviess County extension agent for horticulture. Her column runs weekly on the Home & Garden page in Lifestyle. Email her at annette.heisdorffer@uky.edu.


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