How to grow and harvest sweet corn

Home-grown sweetcorn is a real delight, and, with some of the most recent hybrids, remarkably easy to grow.

Sowing to harvest: 12 to 16 weeks.

Yield: At least two cobs to a plant.

Conditions preferred: Cool temperate to subtropical.

Positioning: Open and sunny.

Soil: Any, if enriched with compost.

Sowing and planting

The soil for sweetcorn should be improved by the addition of compost during the annual digging in autumn or early winter. Then two weeks before planting top dress the soil with vegetable fertilizer at the rate of 135gm per sq m (4oz per sq yd). The sweetcorn plants can be raised by sowing the seeds indoors between mid-spring and late spring. Alternatively you can sow the seeds direct outdoors late spring or early summer. Two seeds should be sown together 2.5 cm (1 in) deep every 45 cm (18 in) along rows spaced 45 cm (18 in) apart; or in blocks, having several short rows, rather than one long row, to reduce the risk of wind damage. Once the seedlings are large enough to handle, thin to leave the strongest plant 45 cm (18 in) apart. Since the roots of sweetcorn are very close to the surface, a moisture-retaining and weed-suppressing layer of peat is beneficial. Do not hoe between the plants; better to let the weeds grow rather than destroy the roots of the sweetcorn. Flood the soil around the plants in dry weather.


Sweet Corn!
Sweet Corn! (Photo credit: davef3138)

The ripe cobs should be twisted free from the plants. Store by freezing.

Pests and diseases

None of any consequence.

SWEETCORN (1) Sweetcorn plants can be raised by sowing the seeds individually, 2.5 cm (1 in) deep in 7.5 cm (3 in) wide peat pots containing peat-based mixture, between mid- and late spring. The pots must be kept in either a greenhouse or indoors on a kitchen windowsill until the risk of frost has passed in late spring or early summer.

(2) Sweetcorn plants should be set out 45 cm (18 in) apart in rows 45 cm (18 in) apart. Since sweetcorn is pollinated by the wind, it is vital that you have a block of plants consisting of at least four rows, to provide satisfactory conditions for complete pollination.

(3) To make sure that the plants are properly pollinated, it is a good idea to give each plant a good shake once the flowers are fully formed to dislodge a shower of pollen from the top on to the female flowers below.

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(4) The first sign that the cobs are ripening is when the silks at the tops of the green-sheathed cobs turn brown. The next step is to make the thumbnail test. Pull back part of the sheath and squeeze a couple of corn grains between finger and thumbnail. If the liquid exuded is watery, the cob is not yet ripe. If the liquid is creamy, then you have cobs perfect for harvesting. If the liquid is ‘doughy’, then you are too late and the cobs are not fit for eating.

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