Sweetcorn (Zea mays), is a form of cereal maize that requires a long warm summer for the best results. Although new F1 types perform much better than older varieties. If you live in a cooler northern region, try growing a cold tolerant variety or mini variety with a shorter growing season.
Soil Type: Slightly acid, well drained, moderately fertile soil.
Conditions: Sheltered sunny site.
Ease of Cultivation: Easy to moderate.
Type: Fruiting Vegetable.
Hardiness: Frost tender.
When to Sow: Early Summer.
Harvest Season: July to September.
Sweetcorn needs good light, plenty of water and protection from cold winds to thrive well in the UK climate.
Maize are hungry feeders so unless your soil has been manured the preceding winter, sprinkle a general purpose compost around each plant to provide a boost and quickly get them growing.
If you grow two different varieties, separate them by at least 30ft (8 metres) as they easily cross pollinate, often giving poor results. This can be a problem on allotments, where other growers are planting corn. So consult with nearby plot holders before buying seed.
They can be direct sown outside in late May but the results may not be as good. To get direct sown seedlings away early, cover with cloches or fleece until they are growing well. Remove protection once the seedlings develop five true leaves.
Plant in blocks rather than rows to encourage good pollination. Don't plant too close, allowing at least 18in (45cm) between plants each way.
Keep weed free and apply a liquid feed in june to help boost cob production. Keep well watered once the cobs start to form. As the cobs start to swell, apply a high potash liquid fertilizer ever few weeks.
If at any time the leaves appear yellowish, or the plants are not growing well, apply a high nitrogen liquid feed to boost growth.
The seeds and ripening cobs are susceptible to attack from birds and rodents.
Harvest once the tassels have turned brown, usually around 14 weeks after sowing. The kernels should be plump, soft and yellow. Check for ripeness by peeling back the leaves to reveal some of the kernels and squeeze a few to see if a milky liquid is exuded.
A soon as they are picked the sugars begin to turn to starch, so the quicker they are used the better. They will keep for a week or so in the fridge but are best eaten within a few hours of picking.
Sweetcorn are best frozen when fresh. Blanch the cobs for about 4 minutes, cool and dry. Either freeze the cobs whole or strip the kernels off and freeze. They should keep for up to 12 months in the freezer.
Peel away all the outer leaves and silk tassels to expose the kernels. Boil the cobs in a pan of unsalted water for 5-8 minutes. Drain and serve with a knob of butter. The kernels can be nibbled directly off the cooked cobs or the kernels can be stripped off with a knife before cooking.
As well as boiling they can be barbecued with the leaves still on, so they cook in their own steam.
Corn kernels are usually yellow but cream, brown, multi-coloured and even black forms are available. There are large and small varieties, ranging from super-sized sweet cobs to to mini-corns suitable for stir frying.
Sweetcorn 'Cafe' is an early variety that produces bright yellow cobs with a lovely sweet flavour. Available at Marshalls.
Sweetcorn 'Conquerer' (F1 Hybrid) this late maturing supersweet variety is well adapted to UK weather. Vigorous plants up to 7ft (210cm) tall, averaging three, 8in (20cm) cobs per plant. Thompson & Morgan.
Sweetcorn Earlybird (F1 Hybrid) a deliciously sweet variety that is cold tolerant allowing it to mature more quickly. Available at Gardening Direct.
Sweetcorn 'Early Xtra Sweet' (F1 Hybrid) produces cobs with a rich sugary flavour and is easy to grow. Available at Thompson & Morgan.
Sweetcorn 'Golden Gate' a mid season variety that produces good 8in (22cm) long cobs that are super sweet. Ideal variety for cool or wet soils. Available at Thompson & Morgan.
Sweetcorn 'Northern Extra Sweet' (F1 Hybrid) is a reliable performer in British summers and is especially suited to cooler northern districts. Early maturing with good quality, well filled cobs up to 8in (20cm) long. Height to 6ft (180cm). Available at Thompson & Morgan.
Sweetcorn 'Summer Glow' is a supersweet, mid season variety, producing an attractive mix of yellow and white grains on the same cob. Performs well in difficult, cool locations, producing plenty of 8in (20cm) long tasty cobs. Available at Thompson & Morgan.
Sweetcorn 'Swift' (F1 Hybrid) is a tendersweet variety that is quicker to germinate with better vigour than many other varieties. Isolation from other sweetcorn varieties is not necessary. Available at Thompson & Morgan.