To ensure an early crop, sow sweet corn seeds either indoors or in a heated greenhouse. I recommend using Peat Pellets , http://marysheirloomseeds.com/supplies.html or something like it do the delicate roots are not disturbed. Corn does not transplant well.
Seeds should be sown in warm conditions, covered very lightly (depth of ¼ inch) and kept reasonably moist until seedlings emerge.
The sweet corn seedlings should germinate after 10 – 12 days, and once they have fully emerged the weakest seedling from each pot should be removed. If you choose to direct-sow, thin Seedlings 6-8 inches apart.
Water well and if they are being germinated indoors - move to a warm, bright windowsill.
Do not over water.
The young Sweet Corn plants can be planted into their final positions once all danger of frost has passed – around the middle of May, but remember that they will need to be hardened off for a week or so before hand. This can be achieved by either bringing them back under protection over-night or placing them under a cloche or poly-tunnel outside.
Plant corn in well-drained soil with lots of organic matter. Grow in full sun. Mulching around your corn will help keep the free of invasive weeds during the summer. Plant with beans, cucumber, melons, morning glory, potato, pumpkin, soybeans, squash and sunflower. For complete details, read Companion Planting 101.