Corn

Environmental Preferences
  • Light: Sunny
  • Hardiness: Tender annual
  • Soil: Deep, well-drained loam
  • Fertility: Rich pH: 6.0 to 7.0
  • Temperatures: Warm (60 to 75 degrees F)
  • Moisture: Average
Culture
  • Planting: Seed after danger of frost is past; extra sweet varieties should be planted when soil temperature reaches 65 degrees F.
  • Spacing: 8 to 12 inches X 24 to 36 inches; minimum of three rows side by side (preferably four rows) to ensure good pollination
  • Fertilizer needs: Heavy feeder; sidedress when plants are 12 to 18 inches high with I 1/2 to 2 ounces of 21-00 per 10 feet of row
Cultural Practices Sweet corn varieties differ significantly in time to maturity and in quality. Yellow, white, bi-color, standard and extra-sweet varieties are available. Most planted varieties are hybrids which have been bred for greater vigor and higher yields. A continuous harvest can be planned by planting early, mid and late-season varieties, or by making successive plantings of the same variety every 2 weeks or when the last planting has three or four leaves (corn sown in early spring will take longer because of cool temperatures). Use only the earliest varieties for late summer-early fall plantings to assure a good fall crop. Fall-maturing sweet corn will almost always be the highest quality since cool fall nights increase sugar content.

Pollination is a very important consideration in planting sweet corn because good pollination is essential for full kernel develop­ment. Since com is wind-polli­nated, block plantings of at least three or four short rows will be pollinated more successfully than one or two long rows.

Most of the various types of com readily cross-pollinate. To maintain desirable characteristics and high quality, extra-sweet and standard sweet corn should be isolated from each other. A distance of 400 yards or planting so that maturity dates are I month apart is necessary to ensure isolation. Sweet corn plantings must also be isolated from field corn, popcorn or ornamental corn. White and yellow types will also cross-pollinate, but the results are not as drastic.

Newly developed extra-sweet or super-sweet corn varieties convert sugar into starch more slowly than standard varieties. They are not necessarily sweeter than the standard, just-picked favorites (though some cultivars are), but they retain their sweetness for a longer period after harvest. Super­sweet varieties may be less creamy than standard varieties due to genetic differences. This charac­teristic decreases the quality of frozen or canned super-sweet corn, though newer cultivars of extra­sweet corn show improvement.

Early-maturing corn varieties tend to be relatively small plants (called coon corn by old-timers because the ears are easy for raccoons to reach). These should be planted in rows 30 inches apart with plants 8 to 9 inches apart. For medium to large plant varieties, use a 36-inch row spacing with plants 12 inches apart in the row. Be sure to plant a block of rows for good pollination and full ears.

Some gardeners are interested in growing baby corn typically found in salad bars and gourmet sections of grocery stores. Baby corn is actually immature corn. Many varieties are suitable, but 'Candystick' with a 1/4-inch diameter cob at maturity is a good one to try, especially since its dwarf habit means that it requires less garden space. Harvesting at the right time is tricky; silks may be produced when the ears are not filled out. Experimentation is the best way to determine when to harvest baby corn.

It is not necessary to remove suckers or side shoots that form on sweet corn. With adequate fertility, these suckers may increase yield; in some cases, removing them has been shown to actually decrease yield.

Mulching is a beneficial practice in corn cultivation because adequate moisture is required from pollin­ation to harvest to guarantee that ears are well-filled. Since main crops of corn usually ripen during dry periods in Texas, it is espe­cially critical to maintain adequate soil moisture. Mulch reduces the need for supplemental water and keeps the moisture content of the soil fairly constant. Most organic mulches are suitable; newspaper held down with a heavier material on top is an excellent way to conserve moisture in corn.

Sweet corn is normally ready for harvest about 3 weeks after the first silks appear. Corn that is to be stored for a day or so should be picked in the cool temperatures of early morning; excessive heat causes the sugar to more rapidly convert to starch. Of course, the best time to pick corn is just before eating it; country cooks recom­mend having a pot of water boiling as you pick the corn, husking it on your way from the garden to the house! This is an exaggeration, but with standard varieties, sugar conversion is rather rapid. Field heat can be removed from ears picked when temperatures are high by plunging the ears in cold water or putting them on ice for a short time. Store ears in the refrigerator until ready for use. Extra-sweet varieties will also benefit from this treatment, but they are not as finicky.

Common Problems

  • Diseases: Wilt (bacterial disease); smut (especially on white varieties - remove infected part); stunt (transmit­ted by leafhoppers); virus
  • Insects: Corn earworm; European corn borer; flea beetles
  • Other: Birds eating seed; raccoons eating mature ears of corn; gardener's impatience (harvesting too soon)
  • Cultural: Poor kernel develop­ment, failure to fill out to the tip - caused by dry weather during silking states, planting too closely, poor fertility (especially potassium deficiency), too few rows in block resulting in poor pollination; lodging (falling over) too much nitrogen.
Harvest and Storage
  • Days to maturity: 60 to 90
  • Harvest: Pick when husk is still green, silks dry brown, kernels full size and yellow or white in color at the tip of the ear; at milky stage (use thumbnail to puncture a kernel - if liquid is clear the corn is immature; if milky, it's ready; if no say, it is too late); cover un harvested ears checked by this method with a paper bag to prevent insect or bird damage; experienced gardeners can feel the outside of the husk and tell when the cob has filled out; corn matures 17 to 24 days after first silk strands appear; matures more quickly in hot weather, slower in cold weather.
  • Approximate yields: (per 10 foot row) 5 to 10 pounds or about 10 to 20 ears
  • Amount to raise per person: 20 to 30 pounds or about 40 to 60 ears
  • Storage: Refrigerator immediately to prevent sugars from converting into starch; cold (32 degrees, moist (95 percent RH) conditions; keeps 4 to 8 days, but standard varieties will become starchy after only a few days
  • Preservation: Canning; freezing cobs or kernels removed from cobs.