Dull, sticky leaves on your indoor plants might only need cleaning, or be a sign of something more serious. Scale insects and whiteflies suck sap from plants and excrete a sticky substance called honeydew, which coats plant leaves and stems. Both pests infect indoor plants and can seriously damage plant health if the infestation isn't controlled. Scale insects have a waxy coating that protects them from sprays, though soap and alcohol can dissolve it. If you spot pests on your indoor plants, check other plants nearby. Isolating infected plants can help prevent the spread of an infestation in its early stages.
Wipe indoor plant leaves gently with a damp cloth, removing any sticky film, dust or dirt. Work from the top of the plant downwards to avoid wiping dust onto clean leaves. Buff leaves gently with a dry cloth.
Check indoor plants for scale insects, which are flat and oval, and look like tiny shells stuck to plant stems and the undersides of leaves. Spread a sheet of plastic wrap over the soil surface in the pot to catch any insects that fall off when you clean the plant. Add 2 teaspoons of mild dish detergent to a gallon of water and wipe plants with the solution on a soft cloth. Remove as many insects as possible. Rinse with clean water and discard the plastic wrap. Alternatively, remove insects with tweezers or a toothpick, or rub them with rubbing alcohol on a cotton bud. Repeat every two or three weeks for as long as the infestation lasts. Spray with a ready-to-use insecticidal soap weekly or bi-weekly, or according to the manufacturer's instructions, if the infestation is heavy.
Check plants for whitefly, which are tiny white insects that cluster on the undersides of leaves and fly away when disturbed. Hold the plants at a slight angle to avoid whiteflies falling into the soil, and spray with a strong jet of water to dislodge the insects; or vacuum them up in the early morning while they're cold and slow, taking care not to harm the plants. Empty the vacuum bag into a plastic bag and seal it before discarding. Alternatively, spray all parts of plants with insecticidal soap, which kills whiteflies on contact. Repeat twice a week or weekly, or according to the manufacturer's instructions.
Prune off leaves and stems heavily infested with scale insect or whitefly with pruning shears, seal them in a plastic bag and put them in the trash. Disinfect the pruning shears after use by soaking in a solution of 1 part household bleach and 3 parts water. Leave for five minutes, then rinse with clean water and dry.
Things You Will Need
- Soft cloths
- Mild dish detergent
- Plastic wrap
- Toothpick or tweezers
- Rubbing alcohol
- Cotton buds
- Insecticidal soap
- Vacuum cleaner
- Pruning shears
- Household bleach
- Honeydew can turn black when colonized by a fungus called "sooty mold," which is generally harmless. Wet a soft cloth and wring it out until it's damp, then wipe the sooty mold off the plant.
- Quarantine new indoor plants in a separate room for a week and check for signs of infestation before putting them near your other plants.
- Very heavily infested plants are unlikely to recover and should be discarded.
- University of California Ventura County Master Gardeners: Controlling Whiteflies in Your Garden
- Oregon State University Extension Service: Don't Forget to Clean House Plant Foliage
- Cornell University Insect Diagnostic Laboratory: Scales on Houseplants
- University of Florida IFAS Extension: Disinfecting Pruning Tools
- Jupiterimages/BananaStock/Getty Images