Sweet corn seeds does not germinate at soil temperatures below 10 Celsius degrees (50 F) so in warm climates sow seeds in spring in situ at 2.5 cm deep and 7 cm apart, and in cool climates sow indoors in modules and plant out seedlings when the soil temperatures reach 13 Celsius degrees (55 F). For optimum pollination you should plant corn in blocks of at least four plants each way, at about 30 cm apart.
For allowing the plants to develop well you should how shallowly when weeding to avoid damaging the roots. Watering should be done in very dry conditions until flowering stars and again later when the grains are swelling.
A corn plant normally produces one or two cobs that should be picked just before required. You can store them in the freezer as the sweet corn freezes well. You will know that the corn is ready for harvesting once the silks have turned brown and the liquid that appear when you press into a kernel with a fingernail is milky. If the liquid is watery then the corn is underripe and if the liquid is doughy the corn is overripe.