Why does your Plectranthus scutellarioides have sticky leaves? Diagnose the cause and fix it with our step-by-step guide.
Aphids are small, soft-bodied insects that pierce the tender stems and leaves of Coleus to suck out sap, excreting a sugary substance known as honeydew. This honeydew creates the characteristic sticky residue on the leaf surfaces.
Scale insects attach themselves to Coleus stems or leaf veins, feeding on plant fluids and secreting honeydew as a byproduct. Unlike aphids, these pests often look like small, stationary bumps or shells.
Whiteflies congregate on the undersides of Coleus foliage; as they feed, they release honeydew that coats the leaves in a sticky film. This is often accompanied by tiny white flying insects visible when the plant is disturbed.
While not the primary cause of stickiness, sooty mold is a black fungus that grows specifically on the honeydew left behind by sap-sucking insects. It creates a dark, velvety coating that can block photosynthesis in Coleus.
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