Troubleshooting
Stock problems — and how to fix them
Stock (Matthiola incana) 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.
Club root (Plasmodiophora brassicae)
Distorted, swollen roots causing wilting and stunted growth. Matthiola is susceptible as a Brassicaceae member. Improve drainage, lime to raise pH above 7.0, and rotate planting sites annually. No effective chemical cure.
Downy mildew
Yellow patches on upper leaf surfaces with a grey-purple mould beneath, prevalent in cool, damp conditions. Ensure good air circulation, avoid overhead watering, and remove affected leaves promptly. A copper-based fungicide can help.
Failure to bloom (running to seed)
Heat above 18°C (65°F) triggers premature bolting and seed set. Sow at the correct season — autumn in mild climates, very early spring in cool climates — so flowers open during the cool part of the year.
Prevent stock problems before they start
Most stock issues are care-mismatch, not bad luck. Dial in the basics:
Looking for stock in general rather than its problems? Read the full stock care guide — light, water, soil and feeding.
Stock problems — FAQ
Why is my stock club root (plasmodiophora brassicae)?
Distorted, swollen roots causing wilting and stunted growth. Matthiola is susceptible as a Brassicaceae member. Improve drainage, lime to raise pH above 7.0, and rotate planting sites annually. No effective chemical cure.
Why is my stock downy mildew?
Yellow patches on upper leaf surfaces with a grey-purple mould beneath, prevalent in cool, damp conditions. Ensure good air circulation, avoid overhead watering, and remove affected leaves promptly. A copper-based fungicide can help.
Why is my stock failure to bloom (running to seed)?
Heat above 18°C (65°F) triggers premature bolting and seed set. Sow at the correct season — autumn in mild climates, very early spring in cool climates — so flowers open during the cool part of the year.