Thursday, 22 April 2010

Growing Guide - Sweetcorn

Sweetcorn is a great addition to the table and can only be more attractive if you have grown it yourself. Whether it is corn on the cob or popped for a movie night if you grow your own you are going to get the best results. I have tried to find the best information I can for you regarding the growing of sweetcorn to try and help you get the best you can this year.

Growing From Seed - Indoors

When growing from seed it is important to remember that sweetcorn likes a nice deep root bed so make sure you pick deep trays or pods to start them off, or be prepared to ‘upgrade’ the pots once they begin to appear.

Seeds can be planted indoors in April and May which will allow them to be well established for planting out once the frosts have passed around June. It is best to start the seeds off individually, one seed to a pot or seed tray pod at a depth of around 1cm (1/2inch). Make sure you water them well and then leave to sprout. They will need a temperature of around 13-15oC (55-60oF) which you can achieve from a heated propagator, greenhouse or just on your kitchen window sill.

Growing From Seed – Outdoors

It is possible to sow your seeds outdoors, directly into situ in your vegetable patch. This is best done during May and June once the frosts have passed. When planting directly outside it is important to note that the success rate can be hindered by colder weather, birds and pests. When planting in this way you may wish to take precautions to protect the seedlings.

Outdoor propagated seeds need to be planted 45 cm (18inches) apart at a depth of 2.5cm (1inch). Sow two seeds in each hole and once the seedlings are established, remove the weaker plant.

Time to Plant Out

Sweetcorn is a hungry crop so ground that has been prepared with well rotted manure the previous year is perfect. It is not vital however, and preparing the ground a week before planting with fertiliser or chicken manure pellets will work wonders.

Young plants are ready to be planted out by June. You should choose a sheltered, sunny spot to give the best results. Plant in a block formation rather than rows but still leave 38-45cm (15-18inches) between each plant. The block formation allows increased pollination, corn is wind pollinated so this allows and increase in pollination success.

You may which, at this time, to protect the young plants from slugs and snails with a sprinkling of slug pellets or installing slug-traps. Young plants may also benefit from wire to protect them from birds.

Sweetcorn can be grown with many low lying crops, most usually squashes, as the corn grows tall so does not block the light. Lettuces also do well below corn. Climbing beans can also be grown alongside as the corn provides the perfect support.

Harvest Time

Once the green tassels begin to turn black the corn is nearing harvest time. Once the tassels have turned completely black peel back the protective sheath and press your nail into one of the kernels. If the liquid appears creamy then the corn is ripe, if it runs clear then leave for a few more days and try again.

Corn is removed by gently twisting the entire cob or by cutting. It is best for the corn to be peeled and cooked immediately in order to make the most of the freshness and sweetness.

Problems and Issues

Badly placed corn can result in low yields. Ensure the corn is grown in blocks to allow maximum pollination. Birds are a threat to young plants so protecting them with wire or netting is important. Slugs and snails will eat the young plants and leaves, protection through pellets or traps will help decrease this problem.

Sweetcorn is susceptible to a disease called Smut which will cause the cobs to become distorted and sometimes affects the leaves and stalks too. It shows as a soot-like covering and can easily be passed from plant to plant. Try to limit this by choosing smut resistant types and should a lot become infected leave for 5 years before replanting corn there.
Growing Guide at a Glance
Sow -In                      
Sow -Out                      


  1. There's no taste like home grown sweetcorn, picked and cooked within the hour.

  2. I am very proud as my sweetcorn has started to germinate this year...can't wait to eat them!!!


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