Troubleshooting
Sweetcorn problems — and how to fix them
Sweetcorn (Zea mays var. saccharata 'Incredible') 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.
Poor pollination / gappy cobs
Caused by single-row planting or drought at silking. Plant in a square block of at least 4x4 and keep well watered while silks are receptive.
Cold-soil rotting of seed
Sown into soil below ~10°C, seed rots before germinating. Wait for warm soil or start in modules under cover and transplant.
Wind rock / lodging
Tall plants topple in exposed sites. Earth up stem bases as roots brace, and grow in a sheltered block.
Corn earworm / corn smut
Caterpillars enter cob tips; smut forms grey galls. Inspect tips, remove galls promptly and rotate beds to limit carry-over.
Prevent sweetcorn problems before they start
Most sweetcorn issues are care-mismatch, not bad luck. Dial in the basics:
Looking for sweetcorn in general rather than its problems? Read the full sweetcorn care guide — light, water, soil and feeding.
Sweetcorn problems — FAQ
Why is my sweetcorn poor pollination / gappy cobs?
Caused by single-row planting or drought at silking. Plant in a square block of at least 4x4 and keep well watered while silks are receptive.
Why is my sweetcorn cold-soil rotting of seed?
Sown into soil below ~10°C, seed rots before germinating. Wait for warm soil or start in modules under cover and transplant.
Why is my sweetcorn wind rock / lodging?
Tall plants topple in exposed sites. Earth up stem bases as roots brace, and grow in a sheltered block.
Why is my sweetcorn corn earworm / corn smut?
Caterpillars enter cob tips; smut forms grey galls. Inspect tips, remove galls promptly and rotate beds to limit carry-over.