Sweet Corn

(Species: Zea mays - Family: Poaceae)


Sweetcorn and its origins

Sweetcorn is a form of maize that has been an important foodstuff for thousands of years. It is a spontaneous mutation of field corn.

Mexican and Central American cultures ate the vegetable as part of their diet as early as 3400BC. It was grown by Native American tribes and given to European settlers in the late 18th century by the Iroquois tribe. 



Sweetcorn is a form of the cereal crop maize that is harvested when the cobs are sweet and tender in late summer. The golden-yellow cobs, 15-20cms long, nestle in the foliage sheath and are the fruit of the plant which is technically a grain. The cobs are borne on tall stems, 1m-1.80m long.

Two or three cobs grow on one plant. In temperate climates, if the summer is cool, the cobs might not fully ripen but nowadays hybrid so-named 'superset' varieties are bred to mature faster as well as have a sweeter taste. There are also mini-corn varieties available that also mature faster and are ideal for stir-fries used whole, and suit smaller gardens.


How to plant Sweetcorn

It is not difficult to grow but it does need room if a number of sweetcorn plants are to be grown and a reasonable crop of cobs to be obtained. The reason is that the plants must be planted in blocks for ease of wind pollination, with a space of 35cm-45cm cm between each plant. Mini corns can be planted about 20cms apart. From seed to harvest takes approximately 14 weeks.


This plant prefers fertile, well-drained soil that is slightly acidic, but will also grow in normal soil. It needs a sheltered, sunny site in order for the ears of corn to mature.

Prepare the soil earlier in the season with well-rotted manure or compost and about a fortnight before planting, sprinkle fertiliser XX. Seed should either be sown indoors in spring, with the benefit of a heated propagator if possible, or sown direct into their planting positions in late spring. Spring-sown plants should be planted out in early summer.


Sweetcorn plants should not be allowed to dry out, and watering should increase when the ears start to swell. They might also need staking if the site is exposed. 

Determine when the cobs are ripe by pressing a fingernail into a kernel: If a milky cream oozes out, the cob is ripe; if it is watery, the cob is unripe. The sugars in the cob start converting to starch the second it is picked, so fresh corn should be consumed as soon as possible.


To prepare for cooking, strip off the leaves, cut off the stalk and and pull off the silky tassels at the tip.


The plant has no specific pests or diseases but can suffer from slug, mice or bird damage so precautions should be taken. Sweetcorn seedlings should be protected with black cotton to deter birds.


Did you know?

The Native American Iroquois women developed the 'three sisters' way of using their three staple crops - maize, beans and squash - so that each one benefitted from the other. In the top of a mound of soil they would plant a seed of maize and a fortnight later the soil would be further mounded and a bean seed would be sown next to the maize. After both had started to grow, a squash seed would be added to the resulting ridge at the base.


The corn supported the bean, which fixed valuable nitrogen into the soil to feed all three. The squash benefitted from the shade and spread, suppressing weeds and holding moisture in the soil. This ideal way of growing maize including sweetcorn has been adopted by many practical-minded gardeners.

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