Sweet corn is the taste of summer and a popular crop with home gardeners. Growing popcorn, dent corn, and flint corn at home is gaining steam too. But many people struggle with getting their corn to produce fully stocked ears. Part of the trouble stems from traditional garden layouts–planting in long rows. If that's you, change things up this year and try planting corn in blocks for better pollination and plumper ears.

How Corn Is Pollinated

Just like many other crops we enjoy, corn needs to be pollinated. In corn's case, no buzzing insects are needed. Sweet corn and all other types of corn are wind-pollinated. Instead of being transported by bees, moths, birds, and other insects, corn pollen travels with the wind and gravity. 

The tassel at the top of the corn plant is where pollen grains are formed. It's the male flower. A single corn plant can make over two million grains of pollen! Down lower on each plant, inside the ears, ovules (that will hopefully become kernels) of corn are waiting to be pollinated. Each soon-to-be kernel extends a strand of silk, a long stigma tube, to the outside of the husk. 

Pollen deposited on the silk fertilizes the ovule. This is why successful pollination is crucial for the development of the delicious kernels we eat. In other words, those kernels are actually seeds which won’t form if they aren’t pollinated.

Since corn needs wind to transfer pollen around, we can envision that planting in one long row can be detrimental to pollination. Sure, we might get lucky and have the wind blow perfectly down the row, and all would be fine. But the odds are not good. 

Corn planted in blocks can take advantage of multiple wind directions and pollen from surrounding plants, resulting in a much higher success rate for pollination and, therefore, more plump kernels on the ears.

Poorly Filled Ears of Corn

It’s a common issue–ears that don’t fill in or develop poorly. Often, the problem can be narrowed down to one of two problems: poor pollination or drought. 

As mentioned above, if the pollen can't get to the silk, the kernels won't develop. Planting corn in one or even two long rows can be part of the problem. The wind may not be in the direction needed, resulting in poor pollination rates.  

Planting corn too closely spaced can also cause pollination issues (and competition). When corn is planted very tightly, the upper leaves overlap so much that pollen can end up caught in the leaves and never make it down to the silks. If the pollen isn’t getting to the silks, you’ll have spotty, poorly filled ears of corn.

The second common problem is drought conditions during the critical stage of pollination. Corn silk contains a large amount of water. Dry conditions can inhibit the transfer of pollen down the silk and result in poorly formed ears. 

Drought related pollination problems often show as the tip kernels being undeveloped, and additional gaps may be found in the rows. The rows have empty gaps like missing teeth. Corn is always thirsty, but keeping soil moisture steady during the time when tasseling begins and the silks are still cream-colored is critical for home gardeners.

Laying Out Corn Blocks in the Garden

Planting corn in blocks doesn't mean you can't have an efficiently laid-out garden. In fact, leaving typical rows behind can free you up to experiment with other shapes and bed ideas. If you garden in raised beds, try planting an entire bed of corn or half of two adjacent beds to keep them in as much of a block formation as possible. 

Keep in mind that corn will grow tall. Some dent corn varieties can exceed ten feet. Plan your corn blocks so they won’t shade out other, shorter plants later in the summer. For most of us, that means locating corn blocks near the northern or eastern edge of our gardens. Of course, you can take advantage of that shade and plant a block to provide afternoon shade for your garden bench!

While it's tempting to plant corn in a tight spacing, corn is really a large plant, and without room to grow properly, your yields can suffer. Keep seedling spacing at ~12" per plant, with more space between rows. To avoid holes in blocks, plant more than you need and then thin the weakest seedlings once they’re a couple inches tall. It may look like wasted space when they first pop up, but they'll fill it in.

Try the Three Sisters Method

One of the more well-known companion planting systems for corn, used by indigenous peoples for centuries, is called the Three Sisters. Corn, beans, and squash are planted together in mounds or blocks, depending on your application of the idea. The corn is planted first to give it a head start, then the beans and usually the squash is last. The specific timing of each crop depends on your varieties and your growing season length. 

Part of the reason for the success of this planting method (among many good reasons) is the corn gets planted in groups, not spaced out in long rows. Mutual support against wind and better pollination resulting from this block or mound planting of corn produces higher yields. 

Even if you don't plan on growing beans, a prickly, vining crop like squash or pumpkins planted with your corn can help deter raccoons and deer from making a midnight snack of your corn plants. Sweet corn, especially, is a favorite of deer. Take advantage of squashes' roaming growth to ramble about and around the edge of your corn block. 

Weeds and Wind

Besides better pollination, planting sweet corn in blocks can help protect it from tipping over in the wind. A single row or two of corn spaced widely apart is often toppled by wind. When four or more rows are spaced slightly close together, the plants offer mutual support against the wind and can withstand the gusts that may topple individual plants. 

Corn in blocks will also block out sunlight for weeds below, considerably reducing that garden task. And, once the corn is harvested, planting a cover crop to enhance the site and keep weeds in check is easier for a block than a row. 

FAQs about Growing Corn in the Garden

How many rows of corn is enough for good pollination?

To ensure good pollination, plan on planting at least four rows of corn in your block. For example, a garden plot of two dozen corn plants could be four rows wide, with six plants in each row. Thirty corn plants can be grown in the garden in an area slightly larger than the size of a sheet of plywood.

Can I still succession plant corn in blocks?

Absolutely, and I recommend it for sweet corn. Plant a new block every two weeks to ensure a continued harvest of fresh corn. You may need to switch varieties based on time to maturity and the time until your first frosts in the area. After the corn in one block has been harvested, cut down the stalks (leave the roots to decay) and sow a cover crop suitable for your area. 

Corn meant for dried use, like flint corn, dent corn, or popcorn, doesn’t need to be succession planted because you’re waiting for it to dry, not trying to prolong a fresh harvest.

What causes poor corn germination rates?

Poor corn germination is often caused by either a lack of soil moisture or cold soil temperatures. Corn seeds need water to begin germination, and dry, dusty soil doesn't provide enough water. Cold soil temps will delay germination or even allow the seed to rot before it sprouts. 

Wait to plant corn until the soil reaches 55℉ for treated seed (usually a funky color like pink) or 65℉ for untreated seed. If you live in an agricultural area, watch the fields. When you see farmers in the fields with corn planters, the soil has likely warmed enough to plant corn in your garden.

Do I need to separate corn varieties to avoid cross-pollination?

The short answer is yes. Cross-pollination of different sweetness corn (su, se, sh2) can result in poor-quality, starchy corn. Sweet corn should also be kept separate from field corn. 

While the required distances are not practical for home gardeners–250 feet is generally considered the minimum–corn can also be separated by time. To prevent cross-pollination of different varieties of corn in the garden, stagger planting dates by two weeks or plant corn types with different maturity dates. The pollen from one type won’t be able to find the silky ears of the other variety as they aren’t present in the garden at the same time.