Sweet corn is a type of maize which has been bred for its high sugar and low starch content. Once the cob has been picked the sugar in the kernels is steadily converted into starch, which is why the flavour of home-grown sweet corn cooked within an hour of picking is so much better than the taste of shop-bought corn. The 6-8in (15-20cm) cobs are borne on 4-6ft (120-180cm) stems – the tassels at the top of the adult plant are the male flowers; the female flowers are the ‘silks’ above the immature cobs. The plants are decorative as well as useful, but are regarded as semi-tropical by many. There is still a widespread view that sweet corn cannot be grown outside of the southern counties, but this is no longer true. Choose one of the early F1 Hybrids which have revolutionised the reliability of sweet corn in this country. In April raise the seedlings indoors in peat pots for planting outdoors once the danger of frost has passed. Set them out in a sheltered, sunny spot and it would have to be a poor summer for this crop to disappoint even as far north as Lancashire or Yorkshire.

Seed facts
Use a seed dressing before sowing outdoors. A minimum soil temperature of 50°F (10°C) is required for germination.
Expected germination time: 10-12 days
Amount required for a 10ft row: 1/12 oz
Expected yield from a 10ft row: 10 cobs
Life expectancy of stored seed: 2 years
Approximate time between sowing and picking: 14 weeks
Ease of cultivation: Not difficult if you can provide the necessary growing conditions.

Soil facts
· There are two basic soil requirements – good drainage and enough humus to ensure that the ground will not dry out too quickly. Ideally it should be slightly acid, reasonably fertile and deep, but the situation is more important than the soil type.
· Choose a spot in full sun which is sheltered from the wind. Dig in winter, incorporating peat or old compost if the previous crop was not matured. Rake in Growmore fertilizer about 2 weeks before sowing or planting.

Sowing and Planting
· Dig rows 1in (2.5cm) deep and sow in groups of 2 seeds, 18in (45cm) apart. Remove the weaker plant. Rows should be 18in (45cm) apart.
· Sweet corn must be sown or planted in rectangular blocks, not as a single row. This will ensure effective wind pollination of the female flowers.
· Outdoors sowing may be reliable in the south but in other areas sow under cloches or preferably in pots indoors. Root disturbance must be avoided so use 3in (7cm) peat pots – not clay or plastic ones. Sow 2 seeds about 1in (2.5cm) deep in seed compost – remove weaker seedling. Harden off before planting outdoors – leave 18in (45cm) between transplants.

Calendar
· Southern counties: Sow outdoors in mid May – the cobs should be ready for picking in late August or September. For extra reliability and an earlier crop (late July onwards in mild areas) sow under glass as described below.
· Other counties: Sow seeds under glass in mid April-early May and plant out in late May-early June. Alternatively sow outdoors under cloches in mid May – place cloches in position about 2 weeks before sowing.
Sowing time (Outdoors): The end of May; Can plant from mid May under cloches; can extend to early July.
Sowing time (Indoors): Sow under glass at the end of April, and transplant at the end of May or beginning of June.
Picking time: Mid August to mid September; can extend from late July to early October.

Looking after the crop
· Remove cloches when the foliage touches the glass. Protect seedlings which black cotton if birds are a nuisance. Keep down weeds but do not hoe close to the plants.
· Roots will appear at the base of the stem – cover them with soil or a mulch of old compost. The side shoots (‘tillers’) which may develop should not be removed.
· Water in dry weather – this is especially important at flowering time. Stake if the plants are tall and the site is exposed.
· Tapping the tassels at the top of each stem when they are fully developed in late June or July will help pollination. Liquid feed when the cobs begin to swell.

Harvesting
· Each plant will produce one or two cobs. Test for ripeness when the silks have turned chocolate brown. Pull back part of the sheath and squeeze a couple of grains between thumbnail and fingernail. If a watery liquid squirts out then the cob is unripe. If the liquid is creamy then the cob is just right for picking but if the liquid is thick and doughy you have waited too long.
· Carefully twist off the ripe cob from the stem. Do this just before it is required for cooking.

Varieties
Older varieties
These ‘open-pollinating’ varieties produce heavy crops, but they are not as reliable in our climate as the modern F1 hybrid varieties which have been specially bred for our northern conditions.
Golden Bantam: The only example of an older variety which you are likely to find. It keeps its place because it is reasonably early, sweet and with a good reputation for hardiness.

F1 Hybrid varieties
These varieties have made it possible to grow sweet corn outside the favoured mild areas required by many of the older varieties. There are early-, midseason- and late-maturing types – the late-maturing are taller and the cobs are often larger than early-maturing varieties, but always choose an early-maturing type if conditions are less than ideal.
John Innes Hybrid: First choice for many gardeners – early, reliable and vigorous with medium-sized cobs.
Early Xtra Sweet: A little later than John Innes Hybrid, First of All, Earliking, etc, but very popular because the grains have at least twice as much sugar as standard varieties. The cobs are large but there is a precaution – do not grow near any other variety as cross pollination spoils the flavour.
First of All: One of the very early ones – highly recommended for table and exhibition, especially in areas north of the Midlands. The medium-sized cobs are about 6in (15cm) long.
Earliking: Medium height with large cobs. An early variety with a good reputation for sweetness – a popular choice, especially in northern areas.
Early Arctic: A new one, claimed by the suppliers to crop 7 days before Earliking.
North Star: The cobs are large, and most experts recommend this one for maximum reliability in northern districts and in cold and wet summers.
Polar Vee: Another variety which is recommended for northern growers. Alternatively you can choose Northern Belle for the less-favoured areas.
Kandy Kob: Like Early Xtra Sweet, an early variety with an abnormally high sugar content.
Tokay Sugar: An odd one – as early and almost as sweet as Early Xtra Sweet but the kernels are pure white.
Kelvedon Sweetheart: A new variety which is claimed to be an improvement on Earliking.
Kelvedon Glory: The most popular of the midseason varieties. A heavy cropper, producing well-filled 7-8in (17-20cm) the kernels are pale yellow. Recommended for its flavour.
Sundance: A midseason variety which is claimed to be an improvement on the better-known Kelvedon Glory.

Troubles
Smut
Frit Fly