(Radio Iowa) – Iowa is the nation’s top corn grower, with more than 13-million acres devoted to the vegetable, but some Iowans are planting their first small crops of -sweet- corn this spring. Aaron Steil, consumer horticulture specialist at the Iowa State University Extension, says if you’d hoped to have sweet corn by the 4th of July, you would need to have planted in mid-April, but he says there’s still plenty of time to get seeds in the ground. “The last practical planting day, especially for the early varieties, is the end of June,” Steil says. “You would obviously be harvesting later if you planted that late, but you would still be able to get a crop in before frost easily.”

There are many types of sweet corn from which to choose. Steil says the “standard sugary” cultivars have the traditional sweet corn flavor and texture, but are only of the best quality within the first day after harvest, because sugars quickly convert to starch after picking. “Most folks really enjoy sweet corn that has good storage life,” Steil says. “Sweet corn really does start to go downhill very quickly after harvest and so certain varieties, like the super sweet or the augmented super sweets, store pretty well.”

Before buying seed, you’ll need to consider what elements are important, including flavor, sweetness, crunch and kernel color. When arranging your sweet corn plot, plan ahead for irrigation and make sure the soil is well fertilized, because corn uses a lot of nitrogen, as well as phosphorus and potassium.  “Rather than planting corn in long rows, like we so often see it in the field, planting our sweet corn in blocks because it’s wind-pollinated,” Steil says. “When we plant them in blocks, it does a better job of pollinating those ears of corn and you get better filled corn ears. You don’t have those little gap-tooth missing spots in the corn ear.”

Crayon drawings by kids may depict eight or ten ears of corn on each stalk, but Steil says you shouldn’t expect nearly as many. “One good ear can be expected from each stalk of corn,” Steil says. “In general, you can expect in a 10-foot row that you’ll get about 11 to 13 ears of corn, when you properly space your corn plants when you’re planting.”

For a continuous supply of sweet corn, plant early, mid-season and late cultivars. Also, he says to plant only fresh seeds, as old seeds may not germinate well. In addition, keep sweet corn isolated from popcorn as the quality of sweet corn will be lowered if it’s cross-pollinated by other types of corn.