Quick answer
Visible pests or suspicious leaf spots on your flaming Katy should be addressed early. Use the signs below to identify the problem and choose the right treatment.
Mealybugs. 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.
Not a match? Compare the signs below to find the one you have.
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 tell
Fine webbing in the leaf joints, tiny moving dots, and a stippled, dusty look to the leaves. They thrive in the dry air many homes have.
The fix
Dab the leaves and stems clean with a damp cloth rather than rubbing them, give the plant good airflow, and treat with an insecticidal soap or neem product made for houseplants, repeating as its label directs until they are gone. Test the spray on one leaf and wait two days before treating the whole plant, and skip any plant the label warns against. Isolate it from other plants.
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 tell
Silvery, shiny patches on the leaves, dotted with tiny black specks of droppings that wipe off. The insects are slim, 1 to 2 mm long, and run or drop when disturbed.
The fix
Move the plant to another room, rinse the tops and undersides of every leaf, cut off the worst leaves and treat in rounds with an insecticidal soap made for houseplants, as its label directs. Depending on the species, non-feeding stages shelter in the potting medium, plant crevices or on leaves. Sticky cards monitor flying adults. Keep checking for several weeks.
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. Flaming Katy 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.
Inspect new plants before bringing them home, check the undersides of leaves now and then, give it good airflow, and isolate anything infested. Keep pets away from a treated plant until the spray has dried.
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