Planting and care tips for Sweet Corn

By Melanie Mathieson
Gardening Guru

The following provides you with some planting and care tips for growing sweet corn in your own garden.

Soil Preparation
Sweet corn thrives best in deep, naturally rich, easily worked soil. However, any well-drained soil is suitable. Sandy soils are best for early crops since sandy soils warm up faster in the spring than heavy soils such as clay. Sweet corn will adapt to a wide range of soil pH but optimum growth is obtained at pH 6.0 to 6.5. Prepare the soil about 6 inches deep, using either a spade, plow, or rototiller. Break up the clods to insure good contact between the soil and the seed, then rake the soil to level the surface or form hills.

Planting
Sweet corn is a warm season crop requiring a minimum soil temperature of 50°F (60-95°F is optimum) for seed germination. Seed should not be planted earlier than 10 days to 2 weeks after the average date of the last killing frost. If planted too early, poor stands, retarded growth, or frost-killed seedlings may result. However, it may be worthwhile to risk the chance of frost in order to get an early crop. You can also use floating row covers over your plantings until the risk of frost has passed.

Starting out with fresh purchased seed each year is advisable, as sweet corn seed is relatively short-lived (2 years), even under ideal storage conditions. Saving seed from last year’s hybrid crop is not recommended since seed from hybrid plants have considerable variability and usually produces inferior plants and ears or no crop. Seed is not that expensive so you can certainly afford fresh seed each year.

Plant the kernels 1 inch deep in heavy soils and no deeper than 2 inches in very light sandy soils. Space the rows 2 to 3 feet apart. Plant early and mid- season cultivars 8 to 10 inches apart in the row and late cultivars 9 to 12 inches apart. Corn can also be planted in hills or mounds instead of rows. Place 5 or 6 seeds per hill, in hills approximately 3 feet apart. Once the plants have come up, thin to the 3 strongest plants per hill.

Corn is wind pollinated, so plant 4 or more short rows of sweet corn side-by-side rather than 1 or 2 long rows. This will help insure good pollination and ear development. Inadequate pollination results in poorly filled ears.

Once your seed is sown, if poor germination does occur, don’t replant the missing plants because the plants that develop from the replanted kernels will be crowded and shaded by the older plants and then yield poorly. In addition, replants would not be ready for pollination at the same time as the original planting. If the entire stand had very poor germination then it best to replant the entire area.

Fertilize
Corn is a heavy user of nitrogen. HYPERLINK “http://home.howstuffworks.com/preparing-garden-soil6.htm” Fertilize in the spring, again when the corn is 8 inches tall, and again when the plants are 18 inches tall. Side-dress between the rows, using one-third of a pound of complete, well-balanced fertilizer on each side of a 10-foot-long row. Hill soil around the plant roots at this time to help support the stalks. Ammonium nitrate (33-0-0) is a good fertilizer for corn.

Cross-Pollination and Isolation Requirements
Corn pollen is carried by the wind from the tassels to the silks. Different types of corn can cross-pollinate and contaminate one another. All sweet corn types must be isolated from other types of corn including field corn, popcorn, and ornamental corn because their pollen will turn sweet corn starchy.

In order to preserve the intended sweet quality of the corn you are planting, isolation is recommended to prevent cross-pollination with other types. Isolation can be achieved by:

•Distance: Since pollen is carried by the wind rather than insects, distance can be used as an effective barrier. A distance of 250 feet between different types will result in some contamination, but not enough to materially affect the quality of the produce. A distance of 700 feet should give complete isolation; however, complete isolation is only necessary for scientific and plant breeding purposes. Keep this in mind if your neighbours are close by and they also plant corn. Isolation can be enhanced, although not fully achieved, by avoiding the prevailing wind direction.

•Barrier/Border Rows: If you have a large garden and are planning different types of corn, a considerable amount of contaminating pollen can be diluted by planting two to five border rows between different types. Most of the cross-pollination would occur in these border rows so that isolation distances could be reduced.

Other Care Tips
HYPERLINK “http://home.howstuffworks.com/how-to-water-plants.htm” \t “_self” Watering is very important. Keep the soil evenly moist. Corn often grows so fast in hot weather that the leaves wilt because the roots can’t keep the leaves supplied with moisture.

Although corn requires a lot of water, try to avoid getting water on the tassels as this can affect pollination. Irrigation may be needed during periods of dry weather. Supplement natural rainfall to provide 1 to 1-1/2 inches of water per week. You can check the amount by catching it in cans placed throughout the watered areas or by digging down to see if the moisture has penetrated at least the top 6 inches of the soil.

Be sure to keep weeds under control by regular cultivation as it is easy to control weeds when they are small. Use a shallow cultivation to avoid harming the corn roots. Weeds between corn plants may be a problem, so hoe in a little soil to smother the weeds. If you have planted in hills, add more soil around each hill being careful not to hit any roots of the plants.

Research has shown that removal of corn side shoots (suckers) not only offers no advantage, it may actually reduce yields.
Harvesting
It is very important to harvest sweet corn at the proper stage of maturity. The critical time is the milk stage, a stage when the juice in the kernel appears milky when you puncture the kernel with your thumbnail. Sweet corn remains in the milk stage for a relatively short period, so check the ears frequently. Corn that is too young will ooze a watery material, while ears that are too old will have a tough, doughy-like kernel. During the milk stage, the unhusked ear should feel firm, have full kernels at the tip of the ear, and have brown, dry silks. Generally, ears should be ready about three weeks from silking time.

When harvesting, break the shank (stem of the ear) close to the ear without breaking the main stock or tearing the shank from the stalk. Grasp the ear near the base and bend it down sharply, or bend it to one side with a rotary motion of the wrist.

At first it may be best to hold the shank with one hand and the ear with the other. After picking, use the sweet corn immediately for fresh eating, canning, or freezing. At high temperatures, the sugar in sweet corn is quickly converted to starch, giving it a bland taste. Although many new cultivars have extended storage quality, many older cultivars will lose 50% of their flavor within 12 hours of picking if left unrefrigerated. If sweet corn must be stored before use, keep the temperature as close to 32°F as possible.

Fall Cleanup
End the garden season by cleaning up the garden area and removing plant debris. Make a decision as to where you may want to plant your corn next year and apply manure or compost to the soil to help increase its fertility fir the next season.
These tips for growing sweet corn should get well on your way to enjoying your “fresh from the garden corn” in late summer or the early fall. Good growing!