Courtesy of the Kansas State University Agricutural Experiment Station and Cooperative Extension Service

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May 6, 2013
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Sweet corn: May the right time to plant new, sweeter varieties

Ears of sweet corn are a popular addition to summer meals.

The flavor and quality of freshly picked sweet corn is outstanding.

Take note, though; sweet corn does not adapt well to small garden areas because closely spaced plants will produce only one to two ears.

Here’s a few other pointers:


New hybrid varieties of sweet corn are available.

The colors range from yellow to white to bicolor, yellow and white kernels together on the same ear.

Early varieties that require 65-75 days to mature produce smaller stalks and ears, while later varieties requiring 75 days or longer produce larger plants and larger ears.

New varieties are available with resistance to several common diseases such as maize dwarf mosaic, smut, and bacterial wilt.

Sweet corn differs from field corn by a single genetic factor called the “sugary” or Su gene.

Several new varieties that have higher levels of sugar have been developed.

Common yellow varieties include Gold Cup, Merit, Miracle, Bodacious, Incredible, Jubilee, Sweetie, Sugar Loaf, Sweet Time, and Kandy Korn.

White varieties include Quick Silver, Silver Streak, Sterling Silver, and Silver Queen.

Bicolor varieties include Sweet Sal, Carnival, Calico Belle, and Candy Store.

When to plant

Sweet corn is a warm-season crop and should be planted in mid- to late April.

However, new sweeter varieties have a smaller, more shriveled seed and will rot in cold soil; do not plant these types until early May.

Successive plantings of corn are important to spread the harvest over a longer period.

Make additional plantings when the previous planting is 0.5-0.75 inches tall.


Plants should be 8-12 inches apart in rows at least 3 feet apart.

Do not crowd plantings, as weak, spindly, unproductive plants will result.

Plant the kernels an inch deep. If many seeds fail to germinate, do not attempt to replace missing plants; replant the entire planting.


Sweet corn requires wind to transfer pollen from the tassel (male) to the ear (female).

Plant corn in small blocks or several short rows rather than a single row to encourage better pollination.

Sweet corn pollinates poorly in 100 degrees weather and ears with missing kernels or gaps may result.

Sweet corn may be cross pollinated by other types of corn such as field corn that pollinates at the same time.

If there is a danger of cross pollination, a space of 40-50 feet may be needed as cross pollination can affect flavor.

Sweet corn is a member of the grass family and needs considerably more nitrogen fertilizer than other garden plants.

A of additional fertilizer sprinkled along the row every several weeks is important.

Sweet corn needs regular watering as well because its sparse inefficient root system does not reach to deep soil water.

Apply 1-1 1⁄2 inches of water per week.

Weed control is necessary, especially in young plantings.


Sweet corn is ready for harvest when the juice in the kernel appears milky as you puncture a kernel with your finger.

The ear should be well filled to the tip.

This ideal harvest stage lasts for only a few days in hot weather, and regular checking for maturity is important.

The silks of mature ears are generally completely dry and brown.

Twist and pull the ear from the plant by bending the ear down sharply.

Use corn immediately or store it in a cold place immediately after harvest.

Pick corn early in the morning when it is cool outside.

Common concerns

— Corn earworm

— Smut

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The Fence Post Updated May 16, 2013 07:52PM Published Jul 8, 2013 10:31AM Copyright 2013 The Fence Post. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.