Troubleshooting
Marshmallow problems — and how to fix them
Marshmallow (Althaea officinalis) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Rust fungus
Hollyhock-family rust (Puccinia malvacearum) shows as orange pustules on leaf undersides in humid conditions; remove affected foliage and improve airflow.
Drought stress
Wilting, scorched leaf margins and stunted roots follow dry soil; this wetland species needs steady moisture, so mulch and irrigate in dry weather.
Sawfly and caterpillar damage
Mallow sawfly larvae and caterpillars can skeletonise leaves; pick off by hand or tolerate minor damage on this vigorous regrower.
Flopping stems
Tall stems lodge in rich soil, wind or shade; site in full sun, avoid excess nitrogen and stake in exposed spots.
Prevent marshmallow problems before they start
Most marshmallow issues are care-mismatch, not bad luck. Dial in the basics:
Looking for marshmallow in general rather than its problems? Read the full marshmallow care guide — light, water, soil and feeding.
Marshmallow problems — FAQ
Why is my marshmallow rust fungus?
Hollyhock-family rust (Puccinia malvacearum) shows as orange pustules on leaf undersides in humid conditions; remove affected foliage and improve airflow.
Why is my marshmallow drought stress?
Wilting, scorched leaf margins and stunted roots follow dry soil; this wetland species needs steady moisture, so mulch and irrigate in dry weather.
Why is my marshmallow sawfly and caterpillar damage?
Mallow sawfly larvae and caterpillars can skeletonise leaves; pick off by hand or tolerate minor damage on this vigorous regrower.
Why is my marshmallow flopping stems?
Tall stems lodge in rich soil, wind or shade; site in full sun, avoid excess nitrogen and stake in exposed spots.