How to grow Sweet Corn

Where to plant

Grow sweet corn in full sun in fertile, well drained soil rich in organic matter. It needs soil and air above about 60°F to germinate and grow well, and seed rots in cold or poorly drained ground. The plants grow 6 to 8 feet tall, so plan for the shade they cast over neighboring beds.

In South Florida, sow from fall through early spring; in Central Florida, from January to April; in North Florida, the Gulf South and Texas, in March and April, with a second crop in late summer in some areas. In the desert, sow in February and March to beat the heat. In California, sow from March to July. Across the North, the Midwest, the Mountain West and the Pacific Northwest, sow in May or June after the last frost, and in Alaska in June with early varieties under clear plastic.

Choosing a variety

Sweet corn varieties are standard sugary (su), sugary enhanced (se) or super sweet (sh2). Standard types germinate better in cool soil; all types do well in warm soil. Plant only one type at a time, or time plantings so types tassel at different times: if they cross pollinate, se and sh2 ears lose their extra sweetness. Early varieties have smaller ears and suit short, cool seasons; late varieties suit long, warm ones. UF/IFAS suggests Silver Queen, How Sweet It Is and Sweet Ice (white) and Sweet Riser and Early Sunglow (yellow) for Florida.

How to plant

1. Work compost and a complete fertilizer into the bed before sowing.
2. Wait until after the last frost and until the soil is above 60°F. Under clear plastic, seed can go in 3 to 4 weeks earlier.
3. Sow seed 1 to 2 inches (2.5 to 5 cm) deep and about 7 to 12 inches (18 to 30 cm) apart.
4. Plant in a block of at least three or four short rows, 24 to 36 inches (60 to 90 cm) apart, so pollen falls on the silks.
5. Sow a new block every 10 to 14 days, or plant early, mid and late varieties of the same type together, for a longer harvest.

Watering and feeding

Water regularly, about 1 inch a week, soaking the soil about 6 inches (15 cm) deep in the morning. Water matters most during tasseling, silking and ear fill; drought then gives poorly filled ears with less flavor. Mulch helps hold moisture and keep down weeds.

Corn is a heavy nitrogen feeder. Utah State suggests side dressing with nitrogen when plants are knee high, with 8 to 10 leaves, and again when the first tassels or silks appear, keeping the fertilizer about 6 inches from the plants and watering it in.

Pruning and care through the year

• Weed carefully while plants are small; once growing strongly, corn outgrows weeds. Avoid deep hoeing near the roots.
• In a small planting, help pollination by shaking a cut tassel over the silks, or tapping the tassels when pollen is shedding, as UF/IFAS describes.

Harvesting

Ears are ready about 17 to 24 days after the silks appear, depending on temperature. Pick when the silks are dry and brown, the husks still green and moist, and a kernel near the tip releases milky juice when punctured. Grasp the ear and snap it downward with a twist.

The harvest window is short, about 5 to 7 days for each planting, and sugars turn to starch quickly after picking. Eat corn as soon as possible; refrigerated in its husk, it keeps a few days.