Corn, Zea Mays, Maize
By Rebecca Goodsell, Sonoma County Master Gardener
“Knee high by the Fourth of July”. “Corn as high as an elephant’s eye” (at least in Oklahoma!) So let’s get planting!
Corn is a New World plant with prehistoric origins in the lowlands east of the Andes. This long lost progenitor of maize evolved to produce a kind of maize with each kernel in a separate husk. There are cartoons of this pod corn on ancient Peruvian pottery. When the Peruvian kernels were carried north into Central America, they hybridized with a local grass, producing ‘teosinte’. This new hybrid flourished in Guatemala and became the ancestor of pointed popcorn, dent corn (the most common), flour corn and flint corn. These were carried into the southwestern United States and further into the north and east of North America.
Sweet corn ( zea mays saccharata) was not grown by the Indians. They no doubt had tasted it as a mutation, but sweet corn is more difficult to produce and to maintain the hybrid integrity than zea mays. Sweet corn became popular after the Civil War. There is now a wide variety of sweet corns, with a wide range in sizes, colors, and degrees of sweetness.
In Sonoma County, sweet corn can be planted from May through July. Recommended varieties include ‘Argent’ and ‘Silver Queen’, which are white, and ‘Double Gem’ which is bicolor (white and yellow kernals). Corn is wind pollinated, so it is important to plant it in a block of at least three rows deep (4’ by 4’) and to separate different varieties by at least 300 yards. Direct-seed the kernels, about 2-3 per hill, although you might use four if there are gophers around. Leave about twelve inches between each hill. When the young plants are three to four inches high, you can weed out the stunted ones or transplant strong growers to gaps in the rows. You can interplant, once the shoots are twelve inches high, with beans, which will use the stalks as beanpoles, or pumpkins or winter squash which can meander through the rows. You will have a visual treat come fall, as well as enough stalks to make a proper corn shock.
You will need to water your cornfield frequently to produce full, juicy ears. Corn does not do well in drought conditions, so be prepared to water frequently while the weather stays hot. Frequent weeding is also necessary. If this is beginning to sound like a lot of work, remember that sweet corn fresh from the garden provides a greater payback than many other vegetables.
You can expect to harvest twenty to forty ears from your three row block in about sixty-five to one hundred ten days. But if the summer is cool, the time could be longer. How will you know when to harvest? After the pollen has been released, the fertilized corn silks will begin to shrivel and turn dry and brown. As the silks continue to dry out, the ear will begin to swell with the enlarging kernels. If you are an impatient sort or impossibly curious as to how everything is going on in there, you could cut a small slit into the husk, near the top, and peer into the ear to check on the plumpness. Puncture a kernel with a sharp knife or fingernail. If the liquid inside is clear, the corn is not yet ready; if the liquid is completely white, the ear is over ripe(too starchy). The best time to pick, when the sugars are best developed, is when the corn liquid is milky, yet still translucent.
Pests are as anxiously awaiting those tender young ears as you are. Corn seedlings are vulnerable to chewing pests like birds, cutworms, earwigs, slugs and snails. You can protect your young seedlings with a floating row cover, or sow indoors and move the seedlings outside when they are larger and more resistant. You may also be able to buy starts at local nurseries. Birds can be deterred by netting, a traditional scarecrow, or a modern one made from old CDs.
If maturing plants get infected with aphids, you can blast them off with a strong spray from the garden hose. Corn earworms sometimes enter the silk end of the ear and chew the kernels - just cut off the end of the ear before cooking. And then there is corn smut. Corn smut is a fungus that produces a grayish-black growth, or gall, that is not poisonous and in certain areas is prized and eaten. ‘Huitlacoche’ (which does not translate as ‘go to bed at eight’) is an important food in Mexico.
What to do with all that corn?. When your writer was younger and lived in Michigan, we went to the garden around 5:00 p.m., and selected an ear for each family member. We husked the corn and saved the brown corn silk to fashion extensions for our dolls’ hairdos.