Troubleshooting
Zucchini / courgette problems — and how to fix them
Zucchini / courgette (Cucurbita pepo) 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.
Powdery mildew
Common in late summer; water at soil level and choose resistant varieties.
Blossom-end rot
Inconsistent watering, not a calcium deficiency.
Female flowers but no fruit set
Poor pollination — hand-pollinate in the morning if bees are scarce.
Squash vine borer
Larvae tunnel inside stems; rotate planting site and protect with row cover.
Yellow leaves
Nitrogen depletion in heavy producers; side-dress with compost.
Prevent zucchini / courgette problems before they start
Most zucchini / courgette issues are care-mismatch, not bad luck. Dial in the basics:
Zucchini / courgette problems — FAQ
Why is my zucchini / courgette powdery mildew?
Common in late summer; water at soil level and choose resistant varieties.
Why is my zucchini / courgette blossom-end rot?
Inconsistent watering, not a calcium deficiency.
Why is my zucchini / courgette female flowers but no fruit set?
Poor pollination — hand-pollinate in the morning if bees are scarce.
Why is my zucchini / courgette squash vine borer?
Larvae tunnel inside stems; rotate planting site and protect with row cover.
Why is my zucchini / courgette yellow leaves?
Nitrogen depletion in heavy producers; side-dress with compost.