Planning Your Corn Crop

By National Gardening Association Editors

If you've never grown corn before, check with a local farm or garden store, a neighbor who raises corn or your Cooperative Extension Service agent before you buy seeds. They can tell you what varieties do particularly well in your area, as well as some of the disease, pest or weather problems you may encounter.

Corn Varieties

When asking for advice, keep in mind that gardeners are often emotionally attached to their favorites. For instance, some people always plant Silver Queen corn, even though the first, creamy white ears won't be ready to harvest until fall. That waiting is part of what makes 'Silver Queen' special, and the long-awaited fall harvest is one of life's fine pleasures. Other people feel the same about 'Country Gentleman' or 'Stowell's Evergreen'.

Sweet corn varieties are usually grouped according to the length of their growing season. You can really extend your harvest by planting more than one group at the same time. The tassel time won't overlap, so you won't have to worry about cross-pollination between varieties.

Despite the preference for a particular type of corn, it's a lot of fun to try a new variety or two every year. However, although the latest hybrids often produce beautifully, watch the results of a few seasons before you depend on a new one for your main crop.

Common Sense and Cross-Pollination

You may come upon words of caution in a seed catalog or have had another gardener tell you to isolate certain types of corn to avoid cross-pollination. It's true that corn's dependence on the wind for pollination means you sometimes have to watch out for accidental mixing of different varieties, but in most home gardens this is a minor problem, if one at all.

The technical explanation for the way corn changes when it's pollinated by another variety has to do with recessive and dominant genes, plus a number of other factors. Luckily, you don't have to be a plant breeder to understand how to keep your garden corn from having an unwanted mix-up. You can just use common sense.

When one type of corn tassels - letting its pollen loose - that pollen can land on the silks of any corn in the immediate area. If only one variety of corn is silking at any given time, crossing cannot take place. This is usually the case in home gardens, where the varieties planted tend to have significantly different flowering and growing seasons.

If two similar varieties cross, the difference in the resulting ears may be unnoticeable. However, because of their genetic makeup, some types of corn suffer if they cross with a stronger or dominant variety.

What's a Home Gardener To Do

There are three instances where this can be a concern in the home garden. First, yellow corn is dominant over white. If a yellow and a white variety cross, the white corn could end up with some yellow kernels. Because it's dominant, yellow corn wouldn't be affected by the cross.

Second, both popcorn and field corn have genes that are dominant over sweet corn. If a cross takes place with either popcorn or field corn and sweet corn, the sweet corn is likely to be tough and starchy. Again, because they're dominant, popcorn or field corn wouldn't be affected by the cross.

Third, many of the genes for supersweet flavor are recessive, so they're affected by any corn that crosses with them. That's why the seed companies advise isolating these varieties.

Corn Isolation

Isolating just means preventing an unwanted cross, and you have a choice of ways to do this. All you have to do is prevent cross-pollination. Simply plan to keep different varieties of corn that enter the tassel and silk stage at the same time far enough apart that their pollens won't mix. The recommendations vary from 100 feet to 600 feet, depending on whom you ask. Naturally, the farther apart the better, but about 200 feet is fine unless you regularly experience very strong winds.

To isolate corn you can choose varieties with different days to maturity, or stagger plantings of varieties that have a similar number of days to maturity. Allow at least 10 days between plantings, and your crops shouldn't cross.

Another trick is to plant the dominant corn on the prevailing downwind side of any variety that will suffer if they cross. If you're not sure in which direction the prevailing winds blow in your area, check with your local weather service.

Some gardeners claim that planting a "fence" of two rows of tall sunflowers between corn varieties is enough to prevent cross-pollination. This works most of the time, because the odds are generally in your favor when it comes to accidental crossing.

Old Favorites

An open-pollinated corn variety is a nonhybrid or a strain that has grown for many generations without plant breeders' modifications. With the revived interest in heirlooms, many other varieties such as 'Country Gentleman', 'Golden Bantam', 'Stowell's Evergreen', and 'Ashworth' are becomming more readily available to home gardeners.

Open-pollinated corn grows just like its parent plants, so you can save the seed from one year to the next with good results. If you want to save the seeds of an open-pollinated variety, isolate the crop from other varieties, so there won't be an accidental mixing of pollens to affect the next generation.

Other articles in this series:
1. Planning Your Corn Crop ← you're on this article right now
2. Corn History and How it Grows
3. Understanding Corn Genetics
4. Corn Growing: Getting Started
5. How to Have the Earliest Corn
6. Sweet Corn Essentials

This article is a part of our Vegetable Gardening Guide for Sweet Corn / Getting Started.

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