Sweet Corn
Zea mays
Sweet corn is wind-pollinated, so plant in a block formation (at least 3×3) rather than a single row to ensure good pollination and full cobs. Start seeds individually in pots under cover in April — sweet corn hates root disturbance, so use deep modules or biodegradable pots that can be planted whole. Transplant after the last frost in late May or early June. Don't rush — cold soil causes poor germination and stunted growth. Choose fast-maturing varieties bred for the UK climate like 'Swift' or 'Sundance'. The cobs are ready when the tassels (silky threads at the top) turn brown and a kernel squeezed with your fingernail releases milky juice. If it's watery, wait longer; if it's doughy, you've left it too late. The sugars convert to starch rapidly after picking, so ideally cook within hours of harvest for the sweetest flavour. Intercrop with beans and squash for a traditional 'three sisters' planting.
Plan where to grow Sweet Corn using our vegetable garden planner.
When to Sow Sweet Corn
Sow sweet corn in April, May, June.
Time to Harvest Sweet Corn
Expect to harvest approximately 3 months after sowing, usually from August to October.
Companion Plants for Sweet Corn
- Cucumber
Outdoor cucumbers can trail beneath the corn block, shading the soil while the tall stems take the light above.
- Runner Bean
Runner beans can climb sturdy sweetcorn stems, as in the 'three sisters' system; give the corn a few weeks' head start, as the beans are vigorous.
- French Bean
Climbing French beans can scramble up sweetcorn stems and add nitrogen to the soil, as in the traditional 'three sisters' planting.
Expected Yield
1–2 cobs per plant; a block of 16 plants typically gives enough for several meals.
Growing Tips
Plant in blocks rather than rows for better pollination
Sweet Corn: common questions
When should I sow sweet corn in the UK?
Sow sweet corn from April to June. Sow under cover (a greenhouse, windowsill or heated propagator) and plant out once the weather has warmed.
How far apart should I plant sweet corn?
Space sweet corn about 30cm apart. It grows to around 1.8m tall. Sow seeds 3–4cm deep.
How long does sweet corn take to germinate?
Sweet Corn seeds usually germinate in 7–10 days (needs soil temperature above 10°C), depending on temperature.
When is sweet corn ready to harvest?
In the UK, sweet corn is usually harvested from August to October. It's ready about 3 months after sowing.
Does sweet corn come back every year?
No. Sweet Corn is an annual: it grows, flowers and dies in one year, so sow it again each year. Some annuals self-seed if a few flowers are left to set seed.
What grows well with sweet corn?
Good companions for sweet corn include Cucumber, Runner Bean and French Bean. See the companion plants section above for why each one helps.
Is sweet corn frost hardy?
No. Sweet Corn is tender and is damaged by frost, so keep it under cover until all risk of frost has passed and bring it in, or grow it under glass, when nights turn cold.
Sweet Corn guides
Plan your sweet corn in the allotment planner
Drag and drop plants onto your plot and get personalised sowing reminders.
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