Proper plant spacing is essential for good yields and has been studied extensively in corn fields because it’s such an important crop.
After looking at advice from gardeners and farmers alike, the best way to space corn in a garden is every 3″ along a row and then thinned out to about 6 inches apart in a row with rows spaced 12-18″ apart. Corn seeds should be planted 1.5-2 inches deep.
Corn planted too close together will increase competition for light, water, and nutrients which can lead to stress and poor ear development.
Thin the corn plants out when they are 4-6 inches tall by leaving the most robust plants and pulling out smaller plants or too tightly spaced plants.
Don’t pull plants to close to each other out by hand to avoid bothering the roots of the corn plant you want to leave, use shears to cut them down.
In the past how far apart to plant corn rows was an easy choice. People planted the rows the amount of space needed for farm animals to pull their plow through.
For us gardeners there is still some practicality to this kind of thinking as we need the rows spaced at least far apart enough to walk through for fertilizer application and pest control.
If you’re growing in raised beds that you don’t need to walk through to reach the plants you can space rows tighter.
How Far Apart to Plant Corn In Raised Beds
Plant corn seeds 3″ apart in all directions or in rows spaced 12″ apart. Thin down to one plant every 6″ when the plants reach 4-6″ tall.
Square foot gardening is an intensive form of gardening with tighter spacing than most gardens. In a square foot garden plants with a recommended in-row spacing of 6″ apart get 4 plants per square foot.
Remember that corn is wind pollinated so if you’re growing a small amount of corn hand pollination is a good idea.
How Far Apart to Plant Corn In Containers
Have pots that are at least 9″ deep and use about 3 lbs. of soil per plant. Plant 2 or 3 seeds in the same spot 1.5-2 inches deep and 6″ apart from each other.
If you are using a 10 gallon container you can do three corn plants per container in a triangle formation. For bigger pots continue to use shapes to get good spacing: a diamond, pentagon, hexagon, etc.
Thin down to one plant per spot a couple weeks after the corn plants have sprouted. Hand pollination is a good idea if you don’t have a large block of corn plants. Read more about that in the flower and pollination paragraphs below.
How Deep to Plant Seed Corn?
Corn seed should be planted from 1.5″-2″ deep when planting outside. If planting in a container plant seed corn in holes 1.5″ deep. I’ve never started corn plants inside but the general rule is to plant seeds shallower in starter pots inside so something like 1″ deep.
How Do Farmers Plant Corn?
Corn farmers start with the same choice as us gardeners, what variety of seed to grow? If weather allows for early planting, a variety that has a longer date to maturity can be chosen and vice versa if the weather doesn’t warm up until later a variety that matures quicker will be chosen. Also for farmers that choose rows 20″ apart they may like a certain variety over another because they feel it does well with less space.
Farmers use a piece of equipment called a planter that is pulled along by a tractor. Planters come in different sizes from 2 rows to 50 rows. Seeders or grain drills are similar pieces of equipment but used for smaller seeds like wheat and other cereals. The planter allows the farmer to set the seed rate and planting depth for the rows.
Most planters will have bulk storage containers for seed and fertilizer and be able to dispense a small amount of starter fertilizer along with every seed. More modern planters use GPS and auto-steer systems on the tractors that allow for precise planting. On uneven fields where the tractor has to make passes over already planted soil these automatic systems will withhold dropping seeds until it is back on unplanted land.
Farmers typically plant rows 20 or 30 inches apart. There is a debate to which method gets more yield with variety chosen and weather of the season all playing their part in yield results.
Farmers aim for 24,000-38,000 corn plants per acre depending on the field’s yield potential and the planting date. It’s common practice to over plant seeds by 5 to 10%. Planting date is a factor because seedlings will have better germination rates later in the spring than early spring when the soil and air temperatures are still cool.
Twin row planting is done by some farmers. It involves having double rows spaced 30″ or 38″ apart. The row of double rows are spaced 7.5″ apart and staggered so that a plant from one row falls in the middle of two plants from the other row forming uniform triangular spacing. Just depends on the farmers opinion as to what gets the best yields.
Planting Corn In Hills or Mounds
Planting corn in hills involves making hills about a foot in diameter and spacing hills along a row 2-3 feet apart. Plant 4-5 seeds 3″ apart in a hill and thin down to 2-3 plants per hill when appropriate. Rows of hills are spaced 2 feet apart.
A mounded or hilled row is the best method in my opinion for most plants in the garden. The mounded row has the benefits of the mound, better drainage and increased soil temperature, and the benefits of the row, increased plant density.
Does Corn Flower?
Corn does “flower” but it does not put out what we normally call flowers. Corn plants are monoecious, meaning that one plant puts off both male and female flowers.
The male flowers are the tassels on the top of the corn stalks. When they mature they shed tiny pieces of pollen that get spread by the wind. Female corn flowers are the silk that protrude from the ears. Each individual piece of silk will become a kernel if it is pollinated.
You can help corn pollination out by manually pollinating ears. You want to hand pollinate when the weather is dry. Take a few tassels off of the tops of the corn plants and place them in a bag and shake it up.
Take pinches of the pollen and spread it on the silks. You can pull back the husk some to expose more of the silks. Do not take all the tassels at once and repeat the process every day for a week.
Corn is pollinated by the wind so you want to have more of a rectangle or square shaped grouping with more rows that are shorter as opposed to one or two long rows. If pollination isn’t successful we end up with no ears or a corn cob that is missing patches of kernels.
To avoid cross pollination if you’re growing different varieties or live near a corn farm the best way is to place bags over the ears before silks appear and to hand pollinate. This way only pollen from the variety you want will pollinate the silks of the ear and become kernels.
If you’ve ever grown a sweet corn and ended up with some kernels on the cob that were more chewy and not sweet your corn plant most likely caught some pollen from a nearby field of corn. Almost every commercial field you see of corn will be field corn and not sweet corn.
Check out “How Does Corn Pollinate & Reproduce” for more on the corn flowering and pollination process.
Please comment with any “corny” or otherwise thoughts, ideas, experiences you have with corn spacing.