How to grow sweetcorn and best varieties

The sheer joy of biting into intensely flavoured, creamy, home-grown sweetcorn makes it an essential summer crop for many veg gardeners.

Which? Gardening has trialled and tasted different varieties at our UK trial ground to recommend the best ones to you.

We also share tips about sowing sweetcorn, how to plant it and how and when to harvest.

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How to grow sweetcorn: month by month

Best sweetcorn varieties

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Full testing results for sweetcorn

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When to sow sweetcorn

Sow in April into deep, 7cm pots or Rootrainers to reduce root disturbance later on. Use a Best Buy compost for sowing seeds. Provide a minimum temperature of 15°C to encourage germination and good growth. Harden off the seedlings to plant out after all danger of frost has passed.

Discover our Best Buy pop-up greenhouses

Caring for your plants

Planting sweetcorn

Choose a sheltered site in full sun, and dig in garden compost or soil improver. 

Wait until the danger of frost has past in mid- to late May. Plant in blocks of at least 12 plants to ensure good wind-pollination, but keep different varieties separate to avoid cross-pollination, which can affect the quality of the cobs. Spacing plants at 35cm generally gives one good cob per plant. Plant further apart (45cm) if you want to try for a smaller second cob, too. 

Help your plants with a recommended soil improver

Watering 

Water when the cobs start to form and the silks appear on the ears of corn. At this time it is also a good idea to shake the sweetcorn stems on a still evening. This ensures that pollen released by the male flowers at the top of the plant lands on all the female silks in the cobs below and helps to ensure that every kernel develops.

Try a Best Buy watering can

How and when to harvest sweetcorn

Harvest in: August to September

The cobs should be ripe when all the silks are brown and shrivelled. Peel back the sheath and the kernels should be plump and yellow. Push your fingernail into a kernel –the liquid that is released from it should be milky when the cob is ready for you to eat.

Store your crop in a Best Buy freezer

Common sweetcorn-growing problems

Smut

This spectacular disease likes warm, dry areas and hot summers, when it infects ears of sweetcorn. It is rare for losses of sweetcorn to be serious, despite the alarming appearance of the ears.

Remove the affected ears and throw them away.

Animals

Sweet-toothed critters, such as rats, squirrels and crows, love ripe cobs. Badgers and deer are also excellent at telling when cobs are ripe, so we had to protect our trial crops with an electric fence.

How we test sweetcorn

We sowed 14 varieties of sweetcorn in Rootrainers inside at the start of May. We planted them outside at our trial site in north Gloucestershire at the beginning of June. They were planted in blocks of72 plants with a spacing of 35cm between them, through ground-cover fabric to retain moisture and control weeds. They were protected from badger and deer damage by an electric fence. We harvested cobs as they matured from the 20 plants in the centre of the plot. We measured and weighed the cobs, checking how uniform in size and well filled with kernels they were, then measured how sweet the kernels were up to a week after they were picked. All the cobs were tasted by trained taste-testers. These experts can distinguish and rate the individual components of taste, such as the intenseness of sweetness, and can identify subtle differences in aromas. They also rated how appetising the cobs looked when they were raw and cooked, looking for evenly sized, glossy, plump, pearly kernels, set out in neat rows.