A reader inquired recently how to plant multiple varieties of sweet corn without creating cross-pollination problems. This is an astute question about an issue that isn't discussed very much. Perhaps people who know the ins and outs of sweet-corn pollination assume everyone else does, too. Most people grow just one kind and don't worry about it.
Growing sweet corn should be a simple matter (add dirt and water, wait eight weeks, then shuck), but if you've had problems getting uniform ears of corn, it may be a pollination problem. When pollination doesn't occur properly, the kernels on an ear of corn may be shriveled, arranged randomly or non-existent. It's not a pretty sight, and the corn is usually not edible.
The easiest way to avoid this gardening mishap is to plant one variety of corn under conditions that are optimal for pollination to occur. (Be advised that pollination is something like corn sex. What follows may not be acceptable for all audiences.)
The pollen is a powdery substance that is released into the air when the tassel is shaken by the breeze. Basically, pollen must move from the tassels that grow upright from corn plants to each of the silks along the stem, where the ears form. Each pollinated silk produces a kernel on the ear.
Sweet corn should be planted in a patch of multiple but short rows. If you plant in a couple of long rows, you'll be less likely to get good pollination. If the corn patch is concentrated into a rectangle of at least four rows, the wind can blow in any direction and still be pollinating. It's an efficiency issue.
I have talked to one gardener who hand pollinated his plants when the tassels opened, rather than leave the process to chance. He described in detail shaking the pollen out of the tassels and gently dabbing it onto the silks with a fine cosmetic brush. Another option is simply to sprinkle the pollen over the silks.
For the average home vegetable garden, we are not talking about a lot of work here. Actually, the smaller the stand of corn, the more sense it makes to hand pollinate. In a larger, multiple-row corn patch, pollination is more likely to take care of itself.
The concern about cross-pollination arises when the corn-loving home gardener tries to plant two or more varieties. If pollen from one kind of corn finds its way to the silks of another variety, it produces genetic confusion. In some cases the results are harmless - an ear of corn with white and yellow kernels, for example.
It's important to remember, though, that if cross-pollination occurs, you won't get the variety of corn you intended, and it may not be flavorful or tender. This is particularly problematic with supersweet varieties. You may get tough, misshapen kernels, and the entire crop may be ruined.
One gardening guide suggests planting different varieties at least 400 yards apart. Let's see: According to my math, that's four football fields. Most people do not garden on a lot that large. Nix that.
This raises an interesting issue, though. By this logic, pollination from a neighbor's corn patch should be a concern. I'm not sure what people should do about that. Perhaps gardeners in a given neighborhood could make a pact to plant nothing but Kandy Korn or nothing but Golden Bantam.
It's also possible to plant corn so that different varieties tassel at different times. The problem is that seed packets don't provide this information. A solution may be to plant varieties at least two weeks apart and hope for the best.