To ensure an early crop, sow sweet corn seeds either indoors or in a heated greenhouse. I recommend using Coconut Coir Pellets so the delicate roots are not disturbed. Corn usually does not transplant well but I have had GREAT success with transplanting corn seedlings grown in coconut coir pellets.
Corn 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.
The young 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.
Corn needs soil with high levels of nitrogen for proper growth and development; thus, additional fertilizer can be added at planting or during the growing season. Yellowing leaves are a common sign of nitrogen deficiency. If this occurs, gardeners should add a side dressing of fertilizer like Blood Meal, fish emulsion, chicken manure or compost.
Companion Plants for Corn
Amaranth, beans, cucumber, white geranium, lamb's quarters, melons, morning glory, parsley, peanuts, peas, potato, pumpkin, soybeans, squash and sunflower. A classic example is to grow climbing beans up corn while inter-planting pumpkins. The corn provides a natural trellis for the beans, pumpkins smother the weeds and helps corn roots retain moisture. Corn is a heavy feeder and the beans fix nitrogen from air into the soil however the beans do not feed the corn while it is growing. When the bean plants die back they return nitrogen to the soil that was used up by the corn. A win-win situation. Another interesting helper for corn is the weed Pig's Thistle which raises nutrients from the subsoil to where the corn can reach them. Keep corn away from celery and tomato plants by at least 20 feet.