Make Room for Corn
Corn has a reputation as too big a plant for most gardens. Certainly most of what a person sees varies from pretty tall to gigantic. The original sweet corns, however, were small plants, between four and six feet tall, just the right size for a garden. There are plenty of modern varieties that stay short and still yield hefty, full-sized ears.
Shorter corns are better in smaller gardens because they don't shade nearby crops and are less susceptible to being blown over in a wind, a phenomenon called lodging. New varieties have exceptionally strong root systems and resist lodging. When you fill a raised bed with diminutive plants like these, you can interplant with something like cucumbers. Follow early corn plantings with any of the fall vegetables to get double use from the space.
Another barrier to planting corn, especially for new gardeners, is the baffling number of choices. It used to be that all a gardener had to decide was whether he or she wanted an early or late one, and then what color -- yellow, white or bicolor? Today, there are three distinctly different kinds of sweet corn, sugar enhanced (SE), supersweet (sh2) and normal. Deepening the "cornfusion factor," the catalogs warn us to keep the supersweets far away from all the other kinds or risk ruining the whole crop.
I suspect that many people resolve the issue by not bothering with corn any more. That's an unfortunate choice because corn really isn't hard to grow. It's a classic of the American garden, and if you grow your own you get to experience flavors and textures that you won't find at the local farmstand.
The Mini Corn Patch
There is no minimum size for a patch of corn. You could grow just one plant if you wanted. Four or five of the minicorns in the chart would fit in hal a whiskey barrel. But the standard recommendation that corn should be planted in blocks at least four rows wide is based on the fact that corn is wind-pollinated. If you want to grow a single plant or a single row, you should plan on hand-pollinating your plants.
In a small planting, hand-pollination is not much work at all. Slip a paper bag over the tassels and shake out the pollen. Do this in the morning after the temperature reaches 65° F. Then spread the silk below and sprinkle the pollen over it. Repeat this for three days in a row. Each silk reaches a single kernel-to-be, so needs to get pollen to make a full ear.
If you garden in raised beds, you can fit three or four rows across a four-foot-wide bed, depending on whether your rows start six or 12 inches from the sides. Space the plants about a foot apart in all directions. So a four- by four-foot bed would yield nine to 16 ears of corn; a four- by twelve-foot bed would yield two to three dozen. Most of the time you'll get good pollination from the wind, but for maximum yields, hand-pollinate plants on the edges of small plots.
Time to Plant
Another advantage of the shorter corns is that they tend to be early, maturing in 55 to 70 days. But corn seed sprouts slowly early in the season and can decay before the plant reaches the light. Corn germinates fastest when the soil temperature is around 90° F, but waiting until then means many of us couldn't mature a crop. You can plant normal corn varieties when the temperature at a depth of one to two inches reaches a minimum of 55° F (minimum temperature occurs around dawn). For supersweets and sugar-enhanced varieties, wait until the soil reaches 60° to 65° F. One of the reasons people traditionally plant two and even three kernels at each point is to overcome poor germination in early plantings.
If you want to push the season, the best way is to presprout the seed in moist paper towels inside a plastic bag. Or, start the corn indoors in containers about two weeks before your planting date and then transplant seedlings under plastic tunnels or Reemay.
Sweet corn is also an excellent candidate for late planting. You can pick corn from your garden long after the local market farmers have exhausted their plantings. Though corn is not very frost hardy, it grows well in the cooler weather of early fall, unlike other heat-lovers like tomatoes, eggplant or basil. You can pick the last crop of good corn the day before frost takes the planting.
Late planting means shorter corn. And corn varieties tend to be shorter the farther south you go. The reason is that shorter day lengths push the plant into the flowering stage earlier. So in the North, fall-crop corn may be a foot or so shorter than normal. In the South, varieties advertised as seven to eight feet tall in catalogs may stay under the rather arbitrary six-foot height limit in the chart, especially in later plantings.
When you plant corn after July 1, add 7 to 14 days to the ripening time to account for shorter, cooler days. All season long, separate your successive plantings, either by planting day or by days to maturity, by about two weeks. (One week isn't enough because maturity rates vary with temperature.)
More than most vegetables, corn likes rich soil. At planting time, apply two inches of compost or three pounds of soybean meal, alfalfa meal or 5-10-5 per 100 square feet. Use an organic mulch once the soil is warm.
Watching Corn Grow
Experienced growers have reliable rules of thumb for predicting the stages in the life of a corn plant. When you first see tassels down in the leaves, it'll be about two weeks before the plant reaches full height and begins to shed pollen. Pollen is released for about a week. Note when the silk on the ears has extended about half its full length -- harvest is about three weeks away at this point.
The normal sweet corns stay in prime condition on the stalk for three days, but they ripen unevenly, which extends the harvest. SE and sh2 corns hold prime eating quality a day or two longer, but the ears ripen all together. So for all three kinds of corn, figure that harvest will last about a week.
Learn to pick corn the way you like it by trial and error. The silk should be dry and brown -- usually drier than you really want to wait for. The tips should be full and swollen. But if pollination is incomplete, the tip of the cob may be bare, with full kernels starting several inches down the cob from the tip. If you are unsure, gently pull away the husk and silk and look. Unripe corn has little points on the tops of the kernels. Replace the husk leaves and wait three days to look again. The corn will continue to ripen, though sap beetles and birds may find the ones you open and ruin the tips.
At harvesttime, place a single layer of ears in a plastic bag and refrigerate the corn if more than an hour will pass before you plan to cook it.
Old-fashioned sweet corn, either open-pollinated or hybrid.
Small-Space Sweet Corns
This selective list (corns under six feet) hints at the wide range of interesting sweet corns available today. Raise the bar by only 12 inches and the list would more than triple.
Early Sunglow Hybrid
Improved Golden Bantam
Seneca Horizon Hybrid
Polar Super Sweet