Sweet corn has gotten even sweeter. With the advent of new hybrid varieties over the last 10 years, ears of sweet corn not only taste sweeter when freshly picked, they also hold their sweetness longer in the refrigerator. Before you go out and plant rows of sweet corn for a summer feast, there are some corn genetics you should understand.
The Genes of Corn
What looks like a simple crop really has some interesting genetics behind it. Traditionally, open-pollinated varieties, such as 'Golden Bantam' and 'Hickory King', were grown by farmers and gardeners. These varieties, if grown in separate areas, will produce kernels true to type so they can be saved and planted the following year to grow the same variety.
When hybrid varieties came into their own in the mid-20th century, sweet corn varieties became more standardized and sweeter. Varieties such as the white 'Silver Queen' and bicolored 'Ambrosia' added disease resistance and adaptability. These hybrids produced more and bigger ears of corn. In order to grow these hybrid varieties, you have to plant new seeds every year because the kernels are not true to type.
In the last 20 years super-sweet hybrid varieties have taken corn to new heights. Sugary enhanced (Se) varieties, such as the yellow 'Bodacious' and super-sweet (Sh2) varieties, such as 'How Sweet It Is', produce as much corn as older hybrid varieties but have the ability to hold their sweetness longer after picking. They're more finicky about soil temperature when germinating, and some say their taste is "too" sweet, lacking the old-fashioned flavor. However, being able to store your corn in the refrigerator for days and still have it taste sweet when cooked is a big advantage.
For a good selection of sweet corn varieties, go to the Willhite corn pages.
Whichever varieties you grow, there are some basic techniques that need to be followed for planting, fertilizing, pest control, and harvesting.
Growing Sweet Corn
Plant corn seeds 8 to 10 inches apart in rows 2 to 3 feet apart. Plant in multiple short rows, called "blocks," rather than in a few long rows. This will insure better pollination. A few weeks after planting, hill soil up around the base of corn plants to prevent them from blowing over in the wind or "lodging." Hilling also helps keep the corn patch weeded. Repeat the hilling again in a few weeks.
Since corn is in the grass family, it thrives on nitrogen fertilizer. Amend the soil in spring with compost and then sidedress when the corn is knee-high and again when the tassel (the top pollen-earing structure) forms. Use a high-nitrogen fertilizer, such as cottonseed meal, sprinkled along the row.
Keep the corn patch well watered and consider mulching with hay or straw after your second hilling to conserve soil moisture.
Keeping Pests at Bay
Most gardeners who grow sweet corn will have to contend with four-legged pests and insect pests at one time or another. (Most modern, hybrid varieties are disease resistant, so that's not an issue.) The most common insect is the corn earworm, which is usually found in the kernels at one end of the ear. Just cut off that portion of the ear before cooking because the rest of the ear is fine to eat. To prevent them, squirt a medicine dropperful of mineral oil in the corn silks just after they start to dry.
Another pest, corn borer larvae, tunnel into corn stalks causing them to fall over. Look for telltale signs of "sawdust" at the base of the corn stalk to see if borers are active. If you've had this problem before, spray Bacillus thuringiensis (Bt) on the plants when the silks have partially emerged, and apply a second spray about one week later.
Raccoons have the uncanny knack for knowing just when your corn is ripe. They strike at night, often devastating a patch of corn, pulling down stalks and nibbling on many ears. To prevent their rampage, string an electric fence around the corn patch in spring to "train" them not to enter that area.
If birds are enjoying pecking at your corn, place bird-scaring devices such a tape and plastic owls in the patch to frighten them off.
When To Harvest
For all varieties, timing is everything when harvesting. Feel the end of the ear. If it's rounded or blunt rather than pointed, the ears are ready. The silks also will be dried up. You can cheat and pull back the ends of the husk and pinch a kernel. If it squirts milky white juice, it's ripe. If it's not ripe, cover up the tip well so insects and birds don't attack it.
After harvesting, if you aren't eating them soon, refrigerate the ears to slow the conversion of sugars to starch. Super-sweet varieties naturally hold their sweetness longer in the refrigerator.
For more on growing and harvesting sweet corn, go to the Virtual Vegetable Guides at www.willhiteseed.com/store/asp/guides.asp
Question of the Week
Q. What is the best way to harvest basil leaves?
A. If you just need a single leaf or two at a time, the plant will not miss them -- just take them and pinch the plant back a bit at the same time. If you need a quantity for processing, freezing, or drying, wait until the plant has almost reached its mature size and then trim it back hard. Water and fertilize to encourage regrowth. You should be able to do this several times before the plant becomes exhausted. You can also plant successive crops if you find it easier to pull them up for harvest. Try to harvest before the plants bloom because the leaves will have more oil content. Pinch the plants when they are small to encourage bushiness.