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Home & garden.

16 August 2021

How to grow sweetcorn

Find out how to grow delicious sweetcorn in your garden or allotment. Discover our best sweetcorn varieties and tips for how to grow them.
CT
Ceri Thomas
Sweetcorn

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


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How to grow sweetcorn: month by month

January
February
March
April
May
June



SOW
SOW/PLANT
PLANT
July
August
September
October
November
December

HARVEST
HARVEST



Best sweetcorn varieties

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Best Buy sweetcorn
What it looks like
Variety name
Yield per 16 plants
21 usable cobs
A Best Buy in our previous trial, this variety gave us 21 good cobs from 16 plants. These were long with succulent kernels; all our harvested cobs had 90-100% cob fill, meaning they had kernels all the way to the tip of the cob or just the very tip exposed with no kernels. A supersweet type, we found it tasted sweet and juicy.
What it looks like
Variety name
Yield per 16 plants
18 usable cobs
This is an unusual white-kernelled corn, bred for its crisp texture and intense sweetness. It lived up to its billing in our trial, giving us completely filled and easy-to-pick cobs. Our testers rated it joint-top for its wonderful sweetness and flavour. Being a white-kernelled corn it needs to be isolated from yellow varieties to stop cross pollination.
What it looks like
Variety name
Yield per 16 plants
15 usable cobs
Despite some mechanical damage showing on the seed we bought, this variety germinated well and produced vigorous seedlings that became strong plants. The supersweet type, bred for the British climate, produced a good number of uniform cobs, all with 100% cobfill. The golden kernels were plump, juicy and sweet - and got full marks for flavour.

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.

When to sow

Sow in April into deep, 7cm pots or Rootrainers to reduce root disturbance later on. 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.

Caring for your plants

Planting

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. 

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.

How and when to harvest

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.

Common growing problems

Smut

Sweetcorn can suffer from smut –a disease that causes cobs to erupt with black mould. It’s not common, but destroy affected plants and grow your corn in a different spot next year

Read more about sweetcorn smut.

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.

Read more about badgers.