Troubleshooting
Rough Marshmallow problems — and how to fix them
Rough Marshmallow (Althaea hirsuta) 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.
Mallow rust
Puccinia malvacearum can affect all Althaea species. Orange-yellow pustules on leaves reduce vigour. Remove affected foliage and avoid wetting leaves when watering. In annual culture, simply discard infected plants and start afresh from seed.
Damping off
Seedlings sown in moist, warm conditions may collapse at soil level due to Pythium or Rhizoctonia. Sow thinly in free-draining compost, water sparingly from below, and ensure good ventilation.
Failure to establish in heavy soils
This species strongly dislikes clay or waterlogged ground and will decline rapidly if not given free-draining conditions. The primary cause of poor performance in cultivation.
Prevent rough marshmallow problems before they start
Most rough marshmallow issues are care-mismatch, not bad luck. Dial in the basics:
Rough Marshmallow problems — FAQ
Why is my rough marshmallow mallow rust?
Puccinia malvacearum can affect all Althaea species. Orange-yellow pustules on leaves reduce vigour. Remove affected foliage and avoid wetting leaves when watering. In annual culture, simply discard infected plants and start afresh from seed.
Why is my rough marshmallow damping off?
Seedlings sown in moist, warm conditions may collapse at soil level due to Pythium or Rhizoctonia. Sow thinly in free-draining compost, water sparingly from below, and ensure good ventilation.
Why is my rough marshmallow failure to establish in heavy soils?
This species strongly dislikes clay or waterlogged ground and will decline rapidly if not given free-draining conditions. The primary cause of poor performance in cultivation.