growing sweetcorn in cool climates - eg the UK

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Growing Sweetcorn in the UK – zea mays

This popular vegetable has been developed from maize – a cereal crop grown for the production of cornflour and in many places appropriate cultivars are used as animal feed.

The varieties we sow and grow as a delicious summer vegetable are the unripe kernels of the plant when they are still sweet and ‘milky’.

Sowing and Growing

Sweetcorn is not native to the British Isles where the cool, unpredictable weather can create challenging conditions for a successful harvest. It does need a long, frost free, growing season with fairly warm temperatures to germinate. You can start it in a propagator but must consider where you will grow it on, once germinated, to ensure adequate warmth and light. Sowing in an unheated greenhouse or poly-tunnel in late April should give a long enough growing season but, as the plants dislike being transplanted, it is a good idea to sow into pots [not too small]. That said, I usually sow 2 seeds per pot to allow for poor germination, especially if I am sowing in my poly-tunnel and the spring is cool. Where 2 plants come up together, I have found that they have transplanted separately quite successfully outdoors when strong enough.

Sweetcorn plants can grow to 6ft [2 metres] so they do need a sheltered site in well drained and reasonably fertile soil. Dig in well rotted manure a couple of weeks before planting. If you do have an exposed site, [which I have] stake each individual plant or put a windbreak around the area. These plants need sun and as they are wind pollinated they should be planted in blocks rather than in rows – unless you are planting several rows together. Although the suggested distance between plants is 45cm [18in], I have discovered that this can give a low pollination rate – the plants can look good, the cobs can grow and look great but, when harvested there are few, if any, pollinated and developed seeds. I now plant no more than 30cm [12in] apart and have had a much better crop. Water the plants well in dry weather to help the cobs to mature.

Types and Varieties

Many of the varieties now available are F1 hybrids which will provide very sweet and fairly reliable crops in our cooler climate. Some are earlier than others and some can be picked straight from the stem, peeled and eaten raw [what a treat!].

You may find, in some seed catalogues, varieties which have different coloured kernels [ red, black, mixed colours] which can be interesting to grow but, in my experience, don’t give the sweet succulent cobs we have come to expect.

Baby Corn – Although, I think these vegetables are fairly lacking in flavour, their texture and appearance is now much loved in stir-fries, salads, pasta dishes and other vegetable dishes. The young cobs are not pollinated when harvested so that the individual kernels don’t develop. However, rather than trying to grow these from regular sweetcorn seeds, it is best to buy seeds from an appropriate variety – try Minipop but, be prepared for a lean crop.

Normal sweetcorn seeds can have labels of ‘supersweet’, ‘early’, ‘tendersweet’, etc. Most are F1 hybrids but do look at the varieties on www.The Real Seed Catalogue site which has a range of organic sweetcorn seeds.

Harvesting and Storing

In the UK, even in the south where it is warmer, most corn plants will give 2 – 3 useful cobs, although I did have a friend on my Blog who said that a friend of his was getting 5 cobs per plant. I have never managed more than 3 and have been enchanted to achieve that.

When the ‘silks’ [the long strands at the top of each cob] have turned dark brown and dried the cobs should be ready to harvest. Don’t leave them too long or the kernels will dry out and become unpalatable and tough. Peel back the leaves shrouding a cob or two to see if they are ready – if you are not sure, press into the kernels. When they are juicy/milky without being too wet, they should be ready.  Depending on the variety, they can be eaten raw straight from the cob or in salads. Of course, the favourite method of serving is - to simmer or steam gently for 5 – 10 minutes then serve with butter and black pepper or do try them in sweetcorn fritters.

Sweetcorn freezes real well – cut the kernels off the cob and pack into small containers – no larger than you would use in one meal, as the ‘milk’ can make the kernels stick together. Pack into suitable freezer containers and freeze – this should keep for many months.

Try also in chutneys and relishes.

Nutritional Value

Excellent source of	Useful amounts	Traces
carbohydrate	Dietery Fibre Vitamin C Thiamin –B1, Niacin – B3,  Folate – B9 Magnesium	Viatmins – Vitamin A Minerals – iron, potassium
Low in saturated fat and protein also low in cholesterol and sodium [salt]

Pests and Diseases

Mice, rats, squirrels etc – although I have never seen any of these pests attacking my crops, it has been evident that they have been ‘harvested’ by some nimble fingered raiders if left too long. Harvest as soon as the crops are ready.

Although I have read reports of other problems in sweetcorn crops – frit fly being the most common, I have never experienced this pest.