Sweetcorn

Origin & history

Maize was bred from the wild grass teosinte in Mexico some 9,000 years ago and reached Europe on Spanish ships after 1500. In Germany it was purely a fodder and grain crop for centuries; sweetcorn only caught on in gardens in recent decades, once early-ripening varieties appeared. A neat piece of botany: every single silk thread on the cob belongs to exactly one kernel — a full cob carries several hundred of them.

Varieties

Sweetcorn comes as normally sweet (su), sugar-enhanced (se) and supersweet (sh2) types; supersweet varieties hold their sugar longest after picking but germinate markedly worse in cold soil. Keeping them apart matters: if supersweet corn stands next to ordinary sweetcorn, popcorn or fodder maize, the drifting pollen turns the kernels starchy — so grow only one type per garden. For German summers pick early-ripening varieties; almost everything on sale is an F1 hybrid.

Care

Sweetcorn is a hungry crop and needs warm soil well supplied with compost, plus steady moisture from the time the tassel emerges — drought during flowering costs kernels directly. Once the plants are knee-high, earth up the base of the stems: maize sends out strong prop roots above that point and stands up far better in summer storms. Raise plants individually in pots and never prick them out — maize resents root disturbance and grows on poorly afterwards.

What can go wrong

The commonest mistake is sowing too early: below roughly 10 °C soil temperature maize does not germinate, it rots, and the row comes up patchy. Crows and pigeons pull the seedlings straight back out with the seed attached — netting or fleece over the row until the four-leaf stage settles that. The corn borer overwinters as a larva inside the stalks, so chopping and composting the stubble after harvest instead of leaving it standing removes its winter quarters.

Harvest, storage & kitchen

A cob is ready when the silks are brown and dry and a kernel pressed with a fingernail releases milky juice — clear juice means too early, doughy means too late. The sugar turns to starch quickly once the cob is snapped off, so sweetcorn should go into the pot the same day or straight into the cold. Blanch any surplus briefly, then strip the kernels off the cob and freeze them.

Frequently asked questions

When do you sow sweetcorn?

Straight into the bed from 10 May to 5 June, about 3 cm deep; for a head start, raise plants from mid-April and set them out from 20 May. Sown a fortnight later, sweetcorn usually catches up in warm June soil.

How many sweetcorn plants do you need for well-filled cobs?

At least four short rows side by side, around fifteen plants in total, spaced 30 cm within the row and 60 cm between rows. The squarer the block, the more completely the cobs fill with kernels.

How many cobs does one sweetcorn plant carry?

Usually one or two, and only the upper one fills reliably. More yield comes from more plants, not from more cobs per plant. Harvest runs from mid-August to the end of September.

Is sweetcorn winter hardy?

No, it is frost tender and sown fresh every year. A late frost in May already damages the seedlings, and in autumn the first frosty night ends the plant — whatever is still on the stalk will not finish ripening.