Grow your own: Sweetcorn

Mar 3, 2023

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There is nothing more delightful on a warm summer’s evening than eating barbecued home-grown sweetcorn; the juices and melted butter dribbling down your chin. It’s simple to grow your own and a great one to involve children in. You’ll have the kids eating vegetables in no time!

Sweetcorn is a type of maize and it produces its cobs of yellow kernels nestled among leaves on very tall 1.8m (6ft) stems. There are usually one to three cobs produced per stem.

The top of the plant produces tassels, which are the male flowers, the female parts are the silks sticking out of the immature cobs on the plant below the tassels.

The pollen from the male part of the flower has to land on the silks to pollinate the female flowers and swell the cobs. This is done by the breeze blowing the pollen on to the silks. It is for this reason that sweetcorn needs to be grown in a block formation and not just in a single line.

There is a greater chance of the female flowers getting pollinated this way.

Sweetcorn Varieties

‘Extra Tender and Sweet’
A quick germinating variety and said to be superior in taste and having better vigour than other varieties.
‘Indian Summer’
A super sweet type that is high in sugars and produces red and purple kernels among the yellow ones.

Sowing & Growing Sweetcorn

Sweetcorn is best sown under cover to get it growing quickly before planting out. It is a crop that needs a long and warm season to do well.

Sweetcorn does not like root disturbance so sow into special Rootrainers, which are long, deep pots that open up like a book. Otherwise make your own pots out of rolled-up newspaper or even toilet roll tubes.

There is no need to remove the newspaper or toilet roll when you plant out. Sow two seeds per tube or long pot and place on a greenhouse bench or a windowsill.

In April no extra heat will be necessary. When the seedlings emerge remove the weakest to leave one per pot. Keep the compost moist and grow on in the best well-lit windowsill you have or place in a cloche or mini greenhouse outside.

Growing on sweetcorn

At the end of May or beginning of June when no more frosts are likely, sweetcorn can be planted out.

If possible prepare the soil by adding some well-rotted farmyard manure or garden compost. Then plant the sweetcorn in a block formation spacing plants 45cm (18in) apart. Water in well.

As the crop grows keep the soil moist but especially when the cobs are forming; drought at this stage will cause shrivelled or undeveloped cobs.

Harvesting sweetcorn

The stage to pick sweetcorn is critical. Once the tassels have gone brown, you should check if your cobs are ready to harvest. Do this by peeling back a little of the husk and piercing a kernel, for example with your fingernail. If the liquid is milky, then its ready to harvest! If the liquid is clear, then its not quite ready yet, and if its dry then its gone too far. See this method of testing in action in the video below.

If your sweetcorn is ready, all you need to do is snap it off the plant.

Eat the cobs soon after harvesting – they lose their sweetness the longer you leave them.