Sticky Plant Foliage: What Causes Sticky Plant Leaves

Have you noticed your houseplant has sap on leaves, and on the surrounding furniture and floor? It’s sticky, but it’s not sap. So what are these sticky leaves on indoor plants and how do you treat the issue? Read on to learn more.

What Causes Sticky Plant Leaves?

Most likely sticky leaves on indoor plants is a sign that you have an infestation of scales, tiny insects that latch onto your plant and suck out its moisture, excreting it as this sticky substance called honeydew. Scales won’t necessarily harm your plant, but a large infestation can stunt growth and the honeydew can get everywhere. It’s best to get rid of them if you can.

 First, check to see if it is scale that is causing your sticky plant foliage. Look at the undersides of the leaves and the stem. Scale insects appear as tiny bumps that are tan, brown, or black in color and look kind of like seashells. What you’re looking at is the insects’ hard outer shells that are impervious to insecticidal soap. 

There are a few ways to get around this. One way is suffocation. Apply a horticultural oil or soap to the plant - it won’t get through the scales’ armor but it will stop them from breathing through it. Another option is to dissolve the scales’ armor. Using a soft cloth or cotton swab, apply 2 tsp. (9 ml.) of dish detergent mixed with a gallon (3.5 L.) of water to the plant, then wipe it again with clean water. 

Alternatively, apply a small amount of rubbing alcohol on a cotton swab. Try to wipe away as many scales as possible without harming the plant. You may have to repeat these process every couple of weeks to get all the insects. If the infestation is heavy, follow up with a routine spray of insecticidal soap. Be sure to lay a piece of plastic wrap over your plant’s soil before taking any action, otherwise you might just knock some scales into the soil and prolong the infestation.

In some instances, the sticky leaves on plants may be due to mealybugs or aphids. These can normally be treated by washing the plant down first with water and then thoroughly applying neem oil to the foliage, front and back, and along the stems where the pesky insects are known to gather. 

As with scale, additional treatments may be needed to completely eradicate them.

Cleaning Sticky Plant Leaves

If any leaves are completely covered in scales, they are probably too far gone and should just be removed. For the rest of the plant, even if the scales are gone, you still have the task of cleaning sticky plant leaves. A cloth dampened with very warm water should do the trick. 

This method can be applied to sticky furniture as well as sticky plant foliage.