Well firstly, we’ll establish the difference between sweet corn and the generic term, ‘corn’.
Those lush fields of gold blowing in the summer wind I remember from my English childhood were corn, which in England tends to be a collective term for wheat, oats, barley or rye. Generally speaking, corn in America and Australia means maize – otherwise known as sweet corn. This article is about growing sweet corn.
You can pretty well source sweet corn anywhere in the Western world nowadays, though when I first saw it, it came out of a can, ready stripped from the cobs and with the picture of a (ho, ho, ho!) green giant on the side!
With an intense sweetness and an equally intense bright, yellow colour, corn tends to be a very handy vegetable for mothers. Kids generally enjoy corn, either on or off the cob, and it is full of Vitamins A, B and C – which information may also come in handy for teaching the alphabet as your kids chomp away!
How to Grow Corn
It takes about two to three months to grow sweet corn from start to finish – from planting seedlings to harvesting your crop, between early spring and late summer. Speed of growth will depend on varieties used, and also on how hot the weather is.
Some types of corn can be planted early in the spring for an earlier harvest, and other varieties can be planted mid season, so when you decide which varieties to plant, take account of their optimum growing and harvesting times. Be aware however that corn will cross pollinate – and you may not like the taste of the resultant hybrid plant! So pick varieties that pollinate at different times if you want to plant them together.
The soil needs to be warm and fertile for a good, healthy crop, and preferably rich in nitrogen. If you think ahead, rake well rotted, nitrogen rich manure into the plot in the autumn. Otherwise, about a fortnight or so before you plant your seedlings, weed and remove any large stones from the plot, then enrich the soil with a general fertilizer and rake over to a smooth finish.
Sweet corn likes warm, well draining though moist soil, so be prepared to water the plot often, and possibly position your crop on a slight slope. Consider growing it against a wall – which will soak up the heat of the sun during the day, and retain it in the evening, as well as shelter your corn from too much wind.
You can prepare your plants from seed in early spring by planting two seeds together in a small pot (use the end of a pencil to make a shallow indentation). Water and place on a windowsill, and when the plants are grown to nearly 2 cm, or half an inch, discard the weaker plant and let the other grow stronger outside in a sheltered area.
Plant out after about a month. Each plant should be about 5 – 10cm (2 – 4”) apart, in rows spaced at about 2 feet (60cm). Alternatively, plant seeds straight into the ground after the danger of the last frost has gone – though these will take a little longer to grow.
When they reach about 15cm (6″) high, thin plants to about 60cm (two feet) apart for small varieties , and 90cms (three feet) apart for tall varieties. At about 20cm (8″) tall, fertilize with a nitrogen rich fertilizer – and again at about 45cm or so. You can do this between rows.
Also make sure you weed the area regularly – as the roots of sweet corn are shallow, they can lose the fight for nutrients against voracious weeds. Be sure to weed carefully though, so as not to uproot your precious corn plants. If you pile soil around the base of the stems, this will help protect the roots as well as support the growing plants.
Water a Lot
Sweet corn likes hot growing conditions, and to ensure even moisture as they grow, corn plants need frequent watering. Don’t get water on the silky corn tassels though – this can interfere with pollination, so always water the ground around the roots.
The flowers are the male part of the plant, and they drop their pollen onto the female tassels, positioned where the cobs will develop. If they’re wet, then they can’t pollinate efficiently. You’ll get one or two cobs per plant – remember if you produce a lot, you can easily freeze them!
It’s up to you how big the block plot will be. It just depends on space available and how many cobs you want to harvest in the season. Also more plants per block means more chance that the wind will pollinate your corn!
A Golden Harvest
Pick the cobs when the tassels are brown, and when the kernels are plump and milky. Peel some of the leaves back and check by ‘pinching’ a kernel between thumb and finger. If it’s firm and juicy, then they are ready to pick – twist each cob off its mother plant.
Corn seems relatively free of pests and diseases, though it can be prone to wind damage, which is another reason why it is advisable to plant sweet corn in a block. In the UK, some animals – like squirrels and mice – are attracted to sweet corn. Cut the ends of plastic bottles and cover the cobs with them to dissuade animal pests.
Also smut balls can develop – they are dark galls on the stems and cobs of sweet corn. They will need to be removed and burnt to prevent them producing black spores that will spread and ruin future crops.
In the States, there are several varieties of insects that attack sweet corn and a common pest is the cutworm. Try placing stiff collars of cardboard or silver foil around the stems of the plants at the base to prevent these caterpillars from invading the growing corn.
In Australia, the earworm is a particular danger – it burrows into the ears of your corn. If your plants are healthy and well fed, you may not get an infestation. If you do, spray your plants with Bacillus thuringiensis, or derris dust. This is low impact on the environment, and easy to source.
Better still and if the problem is not too established, pick the worms off. If you keep poultry – they’ll love them! Otherwise, just destroy the worms, and remember keep an eye out for any more.
Try the so called ‘three sisters’ approach to growing sweet corn – namely grow it with squash plants (like courgettes or pumpkins), together with beans.
The beans can twine up the stalks of the corn, and also they fix nitrogen into the soil – sweet corn loves nitrogen rich soils, as indeed do squashes. The leaves of the squash plants shelter the sweet corn roots in very hot weather, as well as providing a much needed natural mulch. This helps prevents the formation of weeds, as well as stopping moisture from evaporating from the soil.