Corn is grown by a lot of home gardeners. There are many pests and diseases that attack corn. Planting corn with good companion plants can improve yields and reduce problems. The famous three sisters (corn, beans, and squash) have been planted together for hundreds of years.
Here are the best companion plants for corn and some to avoid.
Why Does Corn Need Companion Plants?
Companion plants help corn in a number of ways. Here are some of them.
Many aromatic plants, such as dill, borage, thyme, nasturtiums, borage, mint, marigolds, and basil, repel insects that would otherwise harm the corn plants.
Bring Pest Predators
Dill, mint, and basil attract pest predators to the corn. The pest predators eat pests on the corn. In addition, many plants, such as marigolds, dill borage, thyme, nasturtiums, mint, and basil, attract pollinators that benefit the whole garden.
Nasturtiums act as a trap crop for pests that also like corn. The pests would rather be on the nasturtiums than the corn.
Beans and white clover fix nitrogen from the air and excrete the excess into the soil. Corn is a heavy feeder and uses the nitrogen to grow better.
Thyme, nasturtiums, squash, cucumbers, melons, white clover, and lettuce can act as a living mulch to keep the soil cooler and moister and reduce weeds around the corn. They all thrive in the dappled sunlight the corn provides.
Benefit from Corn
Pole beans, squash, melons, cucumbers, and lettuce benefit from being planted around the corn. Corn provides a trellis for beans and shade for the rest.
You can read more about companion plants in my article here.
Top 15 Best Companion Plants for Corn
Here are the top fifteen companion plants for corn and what they do to help.
Part of the three sisters, pole beans are planted after the corn starts growing and climb the corn in search of sunlight. The corn acts as a trellis and in return, the beans fix nitrogen into the soil where the corn can use it. Plant beans at the feet of corn plants to take advantage of this paring.
Squash is the third member of the three sisters. When you plant the beans at the feet of the corn, plant the squash too. The squash benefits from the shade of the corn. The corn benefits from the living mulch of the squash. Squash keeps the soil cooler and moister in the summer heat than bare earth. It also chokes out any weeds. The beans supply enough nitrogen for the squash as well as the corn.
If you don’t like squash, you can use cucumbers instead. They, too, act as a living mulch that keeps the soil cooler and moister than bare soil. Weeds can’t grow under the cucumber plants. Cucumbers benefit from the shade provided by the corn and the nitrogen fixed by the beans.
Dill attracts beneficial insects such as hoverflies, parasitic wasps, and other pest predators. It also attracts pollinators. Finally, dill repels some of the pests that eat corn plants. Plant the dill in a border around the corn as it needs too much sun to grow amongst the corn.
Melons are another plant that can be planted under corn. The melons benefit from the shade while they keep the soil cooler and moister than it would be without them. If you plant pole means too, then the extra nitrogen benefits the melons.
Borage, like dill, attracts pest predators that will eat the pests on the corn. It also attracts pollinators. Finally, it repels tomato worms, which also eat corn, cabbage worms, and other pest problems. The flowers are edible and make a nice addition to salads.
Marigolds are usually planted around tomatoes, but they work for corn, too. They attract pest predators as well as pollinators. When you till the spent marigolds under, they repel root-knot nematodes. Plant marigolds as a border around your corn. They will get too much shade if you plant them amongst the corn.
Mint has a strong smell that repels deer and rabbits from your corn. In addition, mint attracts pollinators. Mint is invasive, so put pots of mint in the rows of corn, or plant mint in the space between the rows. The shade of the corn will keep it from getting too out of hand.
Nasturtiums repel some insects with their peppery scent. They act as a trap crop for aphids and weevils when planted in thick borders around the corn patch. This means the aphids and weevils like nasturtiums more than corn so will not attack the corn when nasturtiums are available. Keep an eye on the pest level and destroy the nasturtiums when the pest level gets high, so no pests migrate to the corn in search of more room and food. In addition, nasturtiums can act as a living mulch when planted around the corn and between rows of corn. Nasturtiums can do well planted under corn in the dappled sunlight.
Thyme repels corn earworms and other pests that will eat corn. Low-growing thyme varieties can be used as a living mulch to keep the soil cool and moist under the corn. Thyme also keeps weeds at bay. Plant thyme between the corn plants and in the spaces between rows of corn.
Basil repels the maize beetle, a chief pest of corn. Plant basil in a thick border (several plants thick) around your corn to protect it from this pest. Basil gets rather large, so it doesn’t get shaded out by the corn. Basil also attracts beneficial insects like pest predators and pollinators to the garden.
When radishes are allowed to bolt, or produce flower stalks, they repel corn borers. They also repel cucumber beetles and other pests before they bolt. Plant them amongst the corn or in the spaces between the rows for the best results. Because radishes are so fast-growing, you will have to plant them every three weeks until the corn is harvested so they are always out there.
According to research from the Kentucky state research farm, sunflowers attract ladybugs to corn. The ladybugs keep aphids under control, so they do not eat the corn. Aphids are a major problem for corn, so this is important. Plant the sunflowers in a thick border around your corn plants to help keep the pesky aphids under control.
This legume fixes nitrogen from the air and puts it into the soil. The corn can then use the nitrogen to grow. In addition, white clover acts as a living mulch to keep the weeds down so you don’t have to hoe as often. White clover draws pollinators to the garden, too. Plant the clover in the rows between the corn and in the spaces between the rows for the best results.
Lettuce benefits from the shade corn provides. You can get several crops of lettuce when you plant it between the rows of corn. Because lettuce roots are rather shallow, it doesn’t compete for nutrients with the corn.
Top 5 Worst Companion Plants for Corn
Some plants just don’t play well with corn. Here are the five worst plants to put near your corn.
Both tomatoes and corn attract the corn earworm and the tomato hornworm. If you plant corn near tomatoes, you risk attracting pests to both types of plants. Plant your tomatoes on the other side of the garden.
Corn provides too much shade for the Brassica family (cabbage, broccoli, cauliflower, Brussel sprouts, etc.). They need more sun than they get when planted around the corn. Plant the Brassicas where they will not be in the shadow of tall plants like corn.
Like tomatoes, eggplants are vulnerable to tomato hornworms. Planting eggplants and corn together doubles the risk hornworms will attack both plants. Plant eggplants on the other side of the garden from corn.
Fennel is a grumpy plant that produces a chemical that keeps other plants from growing near it. Place fennel in a corner away from other plants. It doesn’t have any companion plants but prefers to be alone.
Black walnut trees also produce a chemical that kills plants near them. This chemical is so strong it remains in the soil for years after the black walnut tree is removed. Don’t plant corn around a black walnut tree or where one has been.
In conclusion, companion plants repel insects, attract beneficial insects, act as a living mulch, fix nitrogen, and fix nitrogen. Corn benefits other plants by acting as a trellis and giving plants shade to keep them from getting too hot during the summer. The best companion plants for corn are pole beans, squash, cucumbers, dill, melons, borage, marigolds, mint, nasturtiums, thyme, radishes, basil, sunflowers, white clover, and lettuce. Plants to keep away from corn include tomatoes, eggplant, the Brassica family of plants, fennel, and black walnut trees.