Pests, webbing, and leaf spots on purple heart

How to tell

White, cottony fluff tucked into leaf joints and along stems, sometimes with sticky residue.

The fix

Test isopropyl alcohol of 70% or less on a small part of the plant first and wait 1–2 days to check for leaf damage. Then dab each one with a cotton swab dipped in it. If you use a neem product made for houseplants, follow its label. Test the spray on one leaf and wait two days before treating the whole plant, and skip any plant the label warns against. Check weekly: they hide.

How to get rid of mealybugs →

How to tell

Small, brown, limpet-like bumps stuck to stems and the undersides of leaves, often with sticky honeydew.

The fix

Scrape them off gently with a fingernail or old toothbrush, then treat with a neem or horticultural-oil product made for houseplants, as its label directs, and keep checking. Test the spray on one leaf and wait two days before treating the whole plant, and skip any plant the label warns against.

How to get rid of scale →

How to tell

Small black flies run across the soil and fly up when you water. Their larvae live in soil that stays damp.

The fix

Let the top layer of soil dry between waterings and catch adults on yellow sticky traps. A drier surface discourages egg laying and reduces egg and larval survival. If gnats persist, use a treatment labelled for fungus-gnat larvae on houseplants, following its instructions.

How to get rid of fungus gnats →

How to tell

Brown or black spots, often with a yellow halo, usually after the leaves stayed wet or the soil was overwatered.

The fix

Remove affected leaves, improve airflow, don’t leave water sitting on the leaves, and let the soil dry more between waterings.

How to tell

Dry, bleached, or brown patches only where strong direct sun hits the leaf, with no bugs or webbing. Purple heart wants bright light and some direct sun.

The fix

Shade it from the harshest midday sun for a few weeks, then let it back into the bright spot gradually.