Garden Corner – Why Houseplant Leaves Turn Brown

Kelly Jackson
Christian County Extension Office

Why Houseplant Leaves Turn Brown

If you have houseplants, you may have noticed their leaves turning brown?  There are many reasons this can happen.  Over and under-watering are the most common causes.  Dry air, insects, and diseases may also cause brown leaves.

Over-watering causes leaves to yellow and brown.  Remember to check the soil before you water by feeling the soil with your finger.  If it is wet about an inch down in the soil, wait before watering.  Some plants like the soil constantly moist, while others need to go dry between each watering.  Check your plant’s requirements to determine how dry the soil should be before watering again. Watering a plant a little each day sounds good but can cause the build-up of salts from fertilizer and poor root development.

Reduce the risk of over-watering by growing plants in containers with drainage holes.  The holes allow excess water to flow out of the pot.  Pour off excess water or fill the saucer with pebbles so that the excess water collects in the pebbles, and the plant’s roots are above the water.  This saves time and mess in pouring off excess water.  You can also use an unglazed clay pot as a container which dries out faster, helping to reduce the risk of over-watering.

Under-watering can also cause leaf edges to brown.  Wilted and limp leaves may mean the soil is too dry.  If the soil is drying out too quickly, check the soil moisture more often.  Water a plant before it wilts in order to avoid injuring the plant.

Pot-bound houseplants are also more susceptible to brown leaf edges.  The soil in a pot-bound houseplant is filled with roots.  This reduces the amount of water the soil can hold.  The solution is to increase the watering frequency or repot the plant into a container 1 or 2 inches larger in diameter.  A larger container and new soil mix will reduce the frequency of water.  Check the soil to determine how often you need to water your newly-transplanted houseplant.

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 the plants have been pruned.  Check the fertilizer label and needs of the plant to develop a fertilization schedule.  A water-soluble complete fertilizer containing nitrogen, phosphorus, and potassium is recommended for most houseplants. If over-fertilizing is a problem, take steps to reduce further damage.  White crusty salts on the soil or the pot is one sign of excess fertilizer.  Leach the soil to wash out the excess fertilizer by watering 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 further browning of the leaves occur.  Leaching washes out excess fertilizer and reduces damage.  To help prevent a buildup of salts, avoid over-fertilizing and water the plant thoroughly each time by letting water run out the bottom of the container.

Reduced humidity is another reason leaves turn brown.  Beware of 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 to use an air humidifier or vaporizer to increase the humidity around your plants.

Insects and diseases can cause leaves to turn brown.  Check stems and undersides of leaves for signs of insects.  Light infestations of mealybugs, aphids, and scale insects can be removed with tweezers or by wiping them off with a wet cloth.  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 when present, 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, water your plants carefully and use a well-drained sterilized soil mixture.  Allow air to circulate around the plant and avoid wetting the foliage.  Leaves with disease problems should be removed from the plant.

 

Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin.

UNIVERSITY OF KENTUCKY, KENTUCKY STATE UNIVERSITY, U.S. DEPARTMENT OF AGRICULTURE, AND KENTUCKY COUNTIES, COOPERATING

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