When to harvest corn – for the sweetest results

Working out when to harvest corn is all important for making the most of this sunshine crop. With a narrow window of opportunity when the kernels turn sweet and juicy and before they become hard and starchy, timing your harvest is everything. 

There’s no denying that homegrown corn tastes so much better than any shop-bought cobs. Full of flavour and sweet, milky juices, it’s absolutely delicious roasted, barbecued or simply steamed. Bursting with minerals, fibre and protein, it is a healthy choice and quick to grow, with many varieties being ready to pick in just 70 days. 

One vital ingredient corn needs to grow is warmth. Temperatures of 65 to 70°F (18 to 21°C) are ideal but there are a few recent cultivars that will perform in slightly cooler climates. Ornamental as well as tasty, these tall decorative plants, with their upright stems and loose tassel tops look right at home planted in a border or as a feature in a giant container.

When to harvest corn

If you grow corn, it’s well worth learning to recognize when your homegrown crop is ripe. When you plant corn will vary depending on your location, but when it comes to harvesting, leave it too late and all you will have is a tough, starchy crop fit for the compost. 

‘The tell-tale sign that your sweetcorn is ready for harvesting is when the tassels coming out of the end of the cobs go dark brown,’ say the experts at Hilliers. ‘This shows that they have picked up pollen and fertilized, which is needed in order to produce and ripen the individual corns. 

‘Test by peeling back the sheaf and gently squeezing one of the kernels. If the liquid that comes out is a milky colour, the sweetcorn is ripe and ready. If it’s clear, leave it longer. If there is no liquid at all, you may, unfortunately, be too late harvesting.’ 

Ideally, harvest corn early in the morning, and gently pull and twist each ear or cob down and away from the main stem. Take as many as you need each day during the early stages of the harvest, but be sure to gather all corn in before the first frosts arrive. 

When to harvest popcorn

Popcorn and sweetcorn come from different plants and have varying harvest times. Whereas sweetcorn needs to be picked when the kernels are full of sweet, milky sap, popcorn kernels need to be firm and well coloured.

‘When the tassels on the husks of the cobs have darkened it is time to harvest and dry your cobs,’ say Stephen and Serena Shirley of Victoriana Nursery Gardens. ‘While it is possible to allow the cobs to dry naturally on the plants before harvesting, this requires a fall relatively free form rain. The second disadvantage of drying on the plant is that if mice find the drying cobs, they will decimate them. So cut the cobs with a little extra stalk and gently remove the outer husk and tassel debris.’

When to pick ornamental corn for decorative crafts

Not just for eating, some varieties of corn can be grown for craft and creating spectacular fall decorations. 

‘Ornamental cobs can be used in autumn floral displays,’ says Kris Collins Head of Horticulture at Thompson & Morgan. ‘Leave the cobs to dry on the plants for as long as possible. Harvest ornamental corn cobs when the silky tassels at the end of the cob have turned brown. Peel back the sheath of the cob to reveal the colorful kernels, but do not remove the husk. Use the husk to hang them indoors to dry until ready to use as fall decorations. ‘

How do you know when corn is ready to pick?

The easiest way to test corn on the cob or sweetcorn for ripeness is to take a close look at the silky tassels and kernels. Once the end tassels have turned brown, carefully peel back the cob’s papery outer covering to reveal the kernels. Press with your fingernail. If a milky sap oozes out, then the ear is ripe and is ready to be picked.

If it is still hard, with no juice, fold the covering back over the cob and continue watering and feeding the plant for a couple more weeks before checking again.

Can you pick corn too early?

It is possible to pick corn too early and it won’t be as sweet as it should be, plus it could be hard. As a guide, corn should be ready around three weeks after the silky tassels first appear.

However, you should always wait until the tassels are brown, then peel back the covering to expose some kernels and press using a fingernail. If you are too early, the sap will still be clear, so wait. Keep checking daily, though, as it’s easy to hang on too long and miss the opportunity to enjoy ripe homegrown corn.