As we get ready to plant the spring crops, it's a good time to look at some alternative sweet corn varieties -- ones that hold their sweetness long after you've plucked them from the stalk.

The most popular of the garden and roadside market sweet corns has long been "Silver Queen." Yes, "Silver Queen" is a fine sweet corn. Its sweet flavor comes on a long ear with full, tender kernels.

When consumers go looking for sweet corn, then, Silver Queen is often the variety they ask for. Other favorites over the years have been "Trucker's Favorite," "Golden Cross Bantam," "Seneca Horizon" and "Merit."

All of these old favorites are called standard sweet corn varieties. They differ from field corn by one gene called the sugary gene and are referred to with the abbreviation "su."

Although these varieties have good sugar content, the minute they're pulled from the stalk they begin converting their sugar to starch. Therefore, the longer they've been picked, the less sugar and more starch the kernels have.

Supersweet Corn

In the 1970s, a new type of sweet corn, referred to as supersweet (sh²), was introduced.

Supersweet corn varieties contain two to four times more sugar than the su types, and the gene causes the conversion from sugar to starch to occur much slower. This allows them to retain their sweet flavor much longer than su types.

Often, sh² corn has a fairly thick seed coat that makes them tougher than su types. And they tend to be more watery. They also have to be isolated from standard varieties and don't germinate well in cool soils.

Sugary Enhanced Corn

In 1980, varieties called sugary enhanced (se) were introduced. These have higher sugar content than the su varieties. However, the sugar still converts to starch at the same rate.

Although they stay sweeter longer than su types, they eventually lose their sweetness in the same way. These varieties have tender seed coats, aren't watery and germinate better in cooler soils than sh² types.

More recently, even more varieties have been introduced with a combination of these traits. Some have advantages of all three types.

Latest Combinations

They're sweeter and convert sugar to starch more slowly. Yet they have a tender seed coat and are less watery, too. And they germinate well in cooler, early-spring soils. On the surface, these newer combinations would seem to be the ticket.

However, in many of the combination types, only 25 percent of the kernels will be of the sweeter type. The so-called "synergistic" types are like this. The "improved supersweet" types are actual sh² types with su characteristics as well.

So What's Best?

So, how do you decide what to plant?

Well, the su and se types are not best for shipping, but for garden and roadside sales they're fine. The improved sh² types hold sweetness while otherwise being more like su and se types.

One caution: sh² types should be isolated from su and se types or field corn. Otherwise, they'll cross-pollinate and cause the sh² types to be more starchy.

Isolate these varieties from others by planting them 250 feet apart or by planting so they're 10 to 14 days apart in maturity.

Otherwise, try some of these new corn types. You may be surprised that you can wait until you get back to the house to start boiling the water.