Growing Sweet Corn from Sowing to Harvest

, written by Benedict Vanheems gb flag

Ripe sweetcorn cob

There’s something pretty special about a handsome stand of homegrown sweetcorn. But the real prize lies in harvesting it. Picking the cobs, then excitedly peeling back the sheath to reveal those full, creamy kernels is just magical! And there’s no better treat than cooking them straight away for the sweetest possible taste. If you fancy growing your own sweetcorn this year, you’re in good company. Here are some tips to set you up for sweet success...

Growing Super Sweet Corn

Grow sweetcorn in a spot that receives plenty of sunshine, in soil that’s been enriched with a lot of well-rotted organic matter such as compost. Corn’s lofty habit and feathery tassels makes it an attractive plant in its own right.

Hybrid varieties are usually the most reliable choices for cooler climates. If you want especially sweet cobs, then choose varieties described as such – many will even have the word ‘sweet’ or ‘sugar’ in the name.

How to Sow Sweetcorn

Corn loves the warmth and won’t tolerate frost. While the seeds may be sown directly outside once the soil has warmed up, the safest way to sow is into pots in the protection of a greenhouse, polytunnel or cold frame. That way you can begin sowing three to four weeks before your last frost date and enjoy a head start on outdoor-sown corn – a huge advantage in shorter growing seasons.

Sow eight to ten seeds half an inch (1cm) deep into four inch- (10cm) wide pots. You can use any general purpose or seed-starting potting mix. Alternatively, sow into smaller pots or plug trays, sowing two seeds to each pot or module then removing the weakest of the two seedlings.

Sweetcorn hates the cold and is best started off in a greenhouse, polytunnel or cold frame

Keep pots moist as they grow on. Ideally they should be about six inches (15cm) tall by the time you’re ready to plant them outside. Harden off the plants as your recommended planting time approaches by leaving them outside for increasingly longer spells over the course of about a week.

How to Plant Sweetcorn

Sweetcorn is wind-pollinated, so instead of planting them in a long row, set your plants out in a block for the highest chance of success. If the corn isn’t well pollinated, it will still grow but will be missing many of the kernels from the cob.

Remove your young plants from their pots, then very carefully tease their roots apart. Try to retain as much of the soil around the roots as possible. Now plant your sweet corn 18 inches (45cm) apart in both directions. Dig a hole for each plant, feed the roots to the bottom of the hole then firm the soil back in.

Sweetcorn is best grown in blocks rather than rows for the best harvests

Sprawling squashes make a great companion for sweet corn. The squash will carpet the ground and help suppress weeds as the sweetcorn grows skywards.

Caring for Sweetcorn

Remove any weeds that pop up within your sweetcorn by hand and continue weeding while you are still able to get between the plants. Sweetcorn is sturdy and shouldn’t need supporting. It will appreciate watering in very dry weather, particularly from late summer as the silks appear and the cobs begin to form.

Sweetcorn is ready to pick when the silks turn dark brown

When to Pick Sweetcorn

The cobs are ready to pick when the silks at the end turn dark brown, usually around six weeks after first appearing. If you’re unsure whether a cob’s good to go, try the fingernail test. Peel back the top of the protective sheath then sink a fingernail firmly into a kernel. If it exudes a creamy liquid, it’s ready. If it’s not quite there the liquid will still be watery, and if there’s no liquid the cob is already past its best.

To harvest, twist the cob and pull it away. Aim to enjoy your harvested corncobs as soon as you can. Try it boiled or barbecued then served up with lashings of butter and pepper!

Corn is sweetest cooked as soon as possible after harvesting

Do you know there are even some gardeners who swear by getting a pan of water on the boil before harvesting their sweetcorn so it can go from plot to pan in mere seconds? If you have tips for growing or enjoying super sweet corn, then please share them in the comments section below.

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Show Comments


"Does sweet corn have suckers? Each stalk has 2 stalks coming out. Don't know whether to remove or.leave them.Never seen this before."
Breysach Rebecca on Tuesday 10 July 2018
"Hi Breysach. Yes, sweet corn can produce suckers, which are called 'tillers' on corn. They're actually a sign that the plants are growing in good conditions, though can sometimes come about if plants are injured or damaged in some way, perhaps by hail or insect damage. Whether you leave them or not depends on your growing season. The tillers have the potential to grow on into full-sized stems, which may even produce bonus ears of corn, though this is very much down to chance and how long your summer is. You do not need to remove tillers - just leave them be. They aren't harming the plants and removing them risks harming the main stem. Let them grow on - they may come away naturally, or they may grow on to boost your harvest. Either way is fine."
Ben Vanheems on Tuesday 10 July 2018
"Can I use kernels from a store bought cob as seeds for next year's crop?"
Gerry Ring on Thursday 1 November 2018
"You could dry the kernels out to then store as seed, but the trouble with that is that the resulting seedlings may not come true to type - i.e. they may produce cobs nothing like the ones you bought. This is because a lot of commercially grown corn in hybridised, which means the seedlings are not like the parent plants because new seed must be specifically produced by crossing two types of parent plants, each and every season. There is also the risk that cobs may have been treated some way to extend shelf life, thereby compromising viability of the seeds. It's always best to start from seed sold specifically for sowing."
Ben Vanheems on Thursday 1 November 2018
"can you plant early variety sweetcorn with a later one next to each other."
Gillian Edwards on Thursday 25 April 2019
"Hi Gillian. If you mean side by side, rather than interplanted in the same patch of ground, then yes, absolutely. They may flower at different times. And even if they do flower at the same time and cross-pollinate, this won't affect the quality or distinctiveness of the final cobs. Only if you were to save seeds to sow next year would you potentially come across problems. So yes, if it's simply to eat both this year, go for it. Absolutely, yes, no problem. The blocks of sweetcorn would need to be physically separated "
Ben Vanheems on Thursday 25 April 2019
"Can you plant them straight into the ground outside ?"
Hattie Wade on Sunday 5 May 2019
"Yes, absolutely. You would need to do this once the risk of frost has passed though. The reason most people living in mild/temperate areas start corn off inside is to get a head start, so they are already young plants by the time they go outside. But you can certainly sow direct if you prefer. Sow two seeds per position, at their final spacings, then thin to leave the strongest at each."
Ben Vanheems on Tuesday 7 May 2019
"Growing corn is easy. I prefer Peaches and Cream variety of corn. It is delicious. Do make sure your dirt has good compost on it. Some farmers put manure in their gardens. It must be on the soil for three months before the garden is plowed to plant seeds in."
Rebecca Williams on Saturday 11 May 2019
"Hi Rebecca. Thanks for your tips and experiences. Corn will definitely appreciate a beautifully fertile soil."
Ben Vanheems on Monday 13 May 2019
"do i need to dry the individual kernels from a cob before planting them in the ground? i found some from last year in my freezer... cannot find any corn seed in this area , will planting fresh corn in the ground result in a crop or not?"
William on Friday 31 May 2019
"I think that if the corn hasn't dried out then yes, it's unlikely to germinate, sorry. The kernels need to mature fully on the plant to become viable seed, which means allowing them to dry out. Have you looked online for a source of corn seed - there must be plenty of online retailers who can post out to you?"
Ben Vanheems on Monday 3 June 2019
"is it possible to improve sweet corn by pruning i.e. cut top off or removing leaves? "
Roy Babbington on Wednesday 4 September 2019
"Hi Roy. I've never heard of this being done, so my inclination is that no, this wouldn't help improve sweet corn. Corn tend to reach a certain height and then stop growing so that energy is diverted into producing the cobs. Removing leaves would remove some of the plant's means of producing the energy to do this."
Ben Vanheems on Wednesday 4 September 2019
"Hi Ben Having a pot of boiling water is a no no, why boil away all of those lovely vitamins when all you have to do is put the corn (as it comes off the plant) straight into the microwave (10 mins) or an oven (15 mins). Take them out carefully, peel back the leaves and you have a ready made handle. Pull off the beard and you are good to go. Try it and you will never boil it again. The leaves hold in all of the moisture and flavour."
Sandra on Thursday 5 September 2019
"Many thanks for the suggestion Sandra. I'll give this a go next time. :-)"
Ben Vanheems on Thursday 5 September 2019
"It won't let me put in the link, but if you google Mr Fothergills News Blog Growing Sweet Corn From Sowing To Harvest it has exactly the same text as your webpage, along with a few of the same pictures. Kinda odd. "
Amanda on Friday 31 January 2020
"Hi Amanda. Thanks for letting us know. That's absolutely fine, they have are permission for this. We're always keen to get our handy articles and videos out there, far and wide!"
Ben Vanheems on Monday 3 February 2020

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