Pocket BotanistCheck these first
- Inspect the undersides of the lower leaves for orange bumps.
- Look for irregular brown spots on the upper leaf surfaces.
- Check if the plant is crowded by other vegetation.
Likely causes
Hollyhock Rust
Most likelyHow to tell: Small orange or rust colored bumps appear on the undersides of leaves. Eventually, the leaves turn yellow and drop off.
What to do: Remove and destroy all infected leaves immediately. Do not compost them. Apply a copper based fungicide every 7 to 10 days during wet weather.
Cercospora Leaf Spot
PossibleHow to tell: Dark brown or gray spots with a lighter center appear on the foliage. These spots often have a yellow halo around them.
What to do: Improve air circulation by spacing plants at least 2 feet apart. Water only at the base of the plant to keep the leaves dry.
When to worry
If the spots cover more than half the leaf surface or spread to the stems, the plant will struggle to photosynthesize. Minor spotting is common in late summer and usually does not kill the plant.
Stopping it coming back
Water at the soil level rather than overhead to keep foliage dry. Clean up all plant debris at the end of the season to prevent spores from overwintering.
Not sure which one it is? Photograph your hollyhock.
This page lists the usual causes. Pocket Botanist looks at your actual leaf and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.
Questions people ask
- Will my hollyhock die from rust?
- Usually no, but it will look unsightly. It weakens the plant over time, so treat it early to keep your hollyhock vigorous.
- Should I cut the plant back if it has spots?
- Yes, removing heavily infected leaves helps slow the spread. If the whole plant is covered, you can cut it back to the ground after flowering.
More problems with Hollyhock
This article was generated with AI from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.