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27 January 2021

How to grow sweetcorn

Find out how to grow delicious sweetcorn in your garden or allotment.
Sweetcorn
CT
Ceri Thomas

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

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

Best Buy sweetcorn
What it looks like Variety name Yield per 20 plants
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6.1kg
This supersweet variety has been bred to get a good start in colder climates, with claims that it gives you a week’s head start on other varieties. But in our trial, which was started in May, the cobs were not the earliest, maturing mid-season in late-August for two weeks. However, even if it wasn’t particularly early, it produced a great yield of the biggest cobs in the trial, with pale yellow kernels that turned a golden colour when cooked. The cobs were very sweet, with a full corn flavour with hints of creamy butteriness. The tender, crisp kernels are plump and juicy, making them a real pleasure to eat.
What it looks like Variety name Yield per 20 plants
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3.5kg
The earliest Best Buy variety to mature, all of our seeds germinated and the vigorous, healthy plants were ready to harvest within a week of each other at the end of August. Cobs maintained a good level of sweetness for seven days after picking. The glossy, plump kernels are bright yellow when cooked, with a fresh taste and smell, and full-bodied, sweet flavour. Crunchy and juicy, the kernels have tender skins that are easy to eat. The only downside was that the cobs were a bit variable in size and the number of filled kernels and their colour also varied between them
What it looks like Variety name Yield per 20 plants
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2.5kg
This petite sweetcorn is a good choice for gardeners with kids. The small cobs are well filled to the ends with juicy kernels that come away cleanly from the central husk and have tender skins that won’t get stuck in your teeth. They taste lovely, too – very sweet, with a pleasingly buttery flavour and aroma. All the cobs of this midseason variety matured over one week as August slid into September, and they were the only variety to retain their initial level of good sweetness for a full seven days after harvesting.
What it looks like Variety name Yield per 20 plants
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4.5kg
This has been a Best Buy for more than a decade and remains a great choice. One potential advantage is that it was the latest Best Buy variety to mature, with all of the cobs ready to harvest on the same day in early September, so it still overlapped with some of the mid-season varieties. The large cobs are well filled with crisp, juicy, golden-yellow kernels that are a crunchy pleasure to bite into. They are also very tender to chew and boast skins that melt away

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.

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