Troubleshooting
Arugula problems — and how to fix them
Arugula (Eruca vesicaria) 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.
Bolting in warm weather
The primary challenge with arugula — triggered by long days (>13 hours) and temperatures above 22°C. Once bolted, leaves become small, increasingly pungent, and unsuitable for salads. Make successive small sowings every 2–3 weeks from early spring through early summer and again in late summer through autumn. Choose slow-bolt varieties for summer growing.
Flea beetle damage
Tiny circular shot-holes in leaves created by flea beetles (Phyllotreta species) — extremely common on arugula and all brassicas. Damage is mostly cosmetic on established plants but can devastate seedlings. Cover with fine insect-proof mesh (0.8 mm) immediately after sowing as the most effective control; remove mesh at harvest.
Downy mildew
Yellow patches on upper leaf surfaces with a white-grey fungal sporulation on the undersides, caused by Peronospora parasitica. Most common in cool, humid, damp conditions. Improve plant spacing, avoid overhead watering, and remove affected leaves. Crop rotation and not growing brassicas in the same spot in consecutive years reduces soil-borne spore loads.
Prevent arugula problems before they start
Most arugula issues are care-mismatch, not bad luck. Dial in the basics:
Looking for arugula in general rather than its problems? Read the full arugula care guide — light, water, soil and feeding.
Arugula problems — FAQ
Why is my arugula bolting in warm weather?
The primary challenge with arugula — triggered by long days (>13 hours) and temperatures above 22°C. Once bolted, leaves become small, increasingly pungent, and unsuitable for salads. Make successive small sowings every 2–3 weeks from early spring through early summer and again in late summer through autumn. Choose slow-bolt varieties for summer growing.
Why is my arugula flea beetle damage?
Tiny circular shot-holes in leaves created by flea beetles (Phyllotreta species) — extremely common on arugula and all brassicas. Damage is mostly cosmetic on established plants but can devastate seedlings. Cover with fine insect-proof mesh (0.8 mm) immediately after sowing as the most effective control; remove mesh at harvest.
Why is my arugula downy mildew?
Yellow patches on upper leaf surfaces with a white-grey fungal sporulation on the undersides, caused by Peronospora parasitica. Most common in cool, humid, damp conditions. Improve plant spacing, avoid overhead watering, and remove affected leaves. Crop rotation and not growing brassicas in the same spot in consecutive years reduces soil-borne spore loads.