Visible pests or suspicious leaf spots on your Rex begonia should be addressed early. Use the signs below to identify the problem and choose the right treatment.
Spider mites. Wipe the leaves gently with a damp cloth and dry them off, then 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.
Not a match? Compare the signs below to find the one you have.
How to tell
White, cottony fluff tucked into leaf joints and along stems, sometimes with sticky residue.
The fix
Dab each one with a cotton swab dipped in rubbing alcohol, then treat with a neem product made for houseplants, as its label directs. 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 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
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 of the soil dry out between waterings and catch the adults on yellow sticky traps. The larvae die off once the surface stays dry.
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. Rex begonia wants medium, indirect light.
The fix
Move it back from the glass, out of the strongest sun.
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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