Growing corn at home is one of the real pleasures of summer for gardeners. It’s a versatile garden grain, relatively easy to grow, and the taste of home-grown corn is beyond compare. Here at the Gardzen Test Gardens we’re especially fond of sweet corn, but there are so many wonderful cultivars and heirloom varietals available. While corn is a popular garden plant with a great deal of gardening lore built up around it, there are some common problems that may occur when growing corn at home. One of these is a healthy looking corn plant with fully developed cobs which somehow don’t have a fully develop set of kernels—or any kernels at all! It’s frustrating, but there are reasons for it and by understanding those we can help ensure that our corn plants produce full, healthy—and delicious—cobs! Let’s dig in and learn a bit more about why corn cobs don’t develop kernels and how corn grows in general.
Gardzen Executive Summary
· Kernels on a corn cob develop after they’ve been fertilized by pollen from another corn plant.
· Lack of pollination is the most common cause of undeveloped kernels of corn.
· However, it’s not always due to pollination issue: heat, drought, and soil conditions can also lead to undeveloped kernels or even undeveloped cobs.
· Different patterns of undeveloped kernels on a cob give us clues as to the issue preventing full growth.
· By taking some basic steps in garden layout and plant care, we can help our corn grow full healthy cobs.
Why Corn Cobs Don’t Develop Kernels
There are a number of common reasons why corn cobs don’t develop kernels. The most common cause of undeveloped kernels on corn cobs is pollination, or rather a lack thereof. Corn develops a bit differently than some other plants; before the cob develops to its full size it puts out a tassel of long silky threads that catch pollen and thus fertilize the cob. All strands of the tassel—which, yes, does become the corn’s silk when the cob develops—must be fertilized in order for the cob to develop fully.
This is where the problem often begins. Corn can be fertilized by insects, but the tassels have evolved to catch pollen being spread on the wind. So if there aren’t enough other corn plants around, wind fertilization is less successful, not all strands of the tassel catch their share of pollen, and the cob doesn't fully develop all kernels. The chain of events leading to pollination or a lack thereof may seem complex but once we understand it we can see what’s happening and understand why our cobs don’t have fully developed kernels.
Pollination may be the most common cause of undeveloped kernels, but it’s not the only one. Corn is a fairly robust garden plant that’s adapted to a fairly wide variety of soil and climate conditions. It’s still a plant, however, and it has watering, nutritional, and and sunlight needs. If any of these aren’t being met, cobs may not develop fully.
How to Diagnose Corn Cob Development Problems
The good news is that by looking at the pattern of undeveloped kernels on a cob we can diagnose what happened and correct it in the future. Undeveloped rows of kernels or spotty kernel development is most often a pollination issue. If the entire tip of the cob is undeveloped, however, that’s a sign that either watering or lack of sun may be to blame. If the plant is healthy and thriving but the cob is only partially developed or unevenly developed, that may be a sign of a nutritional issue in the soil.
As you might imagine, this takes a big of experience to diagnose. We’ve tried to include some helpful photos, but it’s always a good idea to talk to an experienced gardener or your local cooperative extension for more details. You can also send us photos via email or in the comments section and we’ll do our best, but it’s generally better to talk to someone who has experience with the conditions and needs of your particular locale.
How to Prevent Undeveloped Kernels and Cobs
While it’s generally not possible to “fix” undeveloped kernels after the cob has grown to full size, there are a few things we can do to help ensure that our corn develops full, healthy, tasty cobs for us. The biggest one is by planting enough corn plants and planting them close together. Like most grains, corn has evolved to grow in large groups to ensure pollination and maximum seed spread. While different varietals of corn have different spacing requirements (always check the seed packet!), planting corn in blocks rather than long single rows so that the plants can pollinate each other is a good start. We don’t always need to plant a large number of corn plants to ensure pollination, but at least eight to 12 depending on the varietal in a question is a good start. We should also remember that corn pollen spreads mostly on the wind, so if there’s not a good breeze going it may help to gently shake our corn plants and help the pollen spread that way.
Once we’ve done our best to ensure good pollination, it all comes down to sun, water, and nutrition. Corn’s pretty adaptable but it does like full sun and regular deep watering, so providing that is a must especially in hot or dry weather. Corn also feeds pretty aggressively so applying fresh compost at the beginning of the growing season and regularly fertilizing throughout is a good idea. The “Three Sisters” system developed by Native American farmers is worth considering as it addresses many of these needs in a space-efficient and all-natural way.
Growing Healthy, Tasty Corn
Corn is one of those wonderful gifts of the summer season. Like watermelon, it perfectly captures everything that makes this time of year special. We hope this article helps you get the most out of your corn by addressing some of the most common issues with kernel and cob development. If you’re not growing corn already, we hope it inspires you to give it a try.
As always, we love to hear from you so if you have questions or tips to share, please reach out via email. Gardzen is all about community and our readers are what make this blog worthwhile
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