Companion planting can help strengthen your garden

Some gardens are bred to be neat and orderly, with distinct rows or groupings for each plant. It can make for an attractive appearance, as different plants come into bloom and add some color to the landscape through the spring and summer. However, mixing crops together may be more beneficial for your garden's health.

Companion planting has long been used to allow plants to mutually benefit each other. The seed company Burpee says one classic example is the "three sisters" strategy employed by Native Americans to grow beans, corn, and squash together. The cornstalks offer a natural trellis for beans to climb, while beans fix nitrogen in the soil and squash leaves help inhibit weed growth by blocking sunlight from reaching the ground.

Plants can work well together in a number of ways, such as deterring pests, making nutrients more accessible, and improving the flavor of crops. You'll need to be cautious in how you lay out the garden, though, as certain species will be harmful to one another.

The simplest form of companion gardening is arranging your plants to ensure that none of them are detrimental to the growth of others. The Gardener's Supply Company says this layout should ensure that plants don't compete for space or sunlight. Know how a plant is likely to spread and how tall it will grow, since you may not be aware of these constraints until later in the season, once vines start to sprawl and taller plants start to shade smaller ones.

One essential aspect of companion planting is proper spacing. Burpee says that rather than establishing large groups or rows of plants, you should mix flowers and herbs among your plants. This process can help confuse pests due to the variety of scents in the garden while also enhancing its appeal to beneficial insects.

This effect is thought to occur because some plants can provide food and shelter for useful insects. The Center for Agriculture, Food and the Environment at the University of Massachusetts says edible herbs like basil, cilantro, dill, and parsley can support creatures like spiders and mantids, which prey on harmful pests.

An intermixture of plant species also improves the garden's diversity, making it less likely to be decimated by a single pest or disease. Even if your companion crops are limited to different varieties of the same vegetable, you can ensure that they'll be more likely to survive and thrive during the season.

Make sure that plants will work well together. The wrong pairing can lead to stunted growth, increased vulnerability to certain pests, or other disadvantages.

For example, the Old Farmer's Almanac says tomatoes can share space with crops like carrots, celery, onions, lettuce, and spinach. However, they'll be more vulnerable to pests if planted alongside corn, since both are affected by the same earworm. Tomatoes should also be kept away from potatoes, since blight from crop one can spread to the other.

Beans use cornstalks to support their vines, and also grow well alongside cucumber, lettuce, and zucchini. They're less beneficial as a companion crop to peppers, since their vines can crowd out this plant.

Onions are particularly helpful as a companion crop since they ward off aphids and carrot flies. However, some plants—such as asparagus, beans, and peas—don't work well with onions since their growth will be negatively affected.

Flowers are good companions as well due to their ability to keep away pests. Marigolds in particular are a gardener's favorite, with Burpee saying it is useful for deterring nematodes and beetles. However, The Center for Agriculture, Food and the Environment says this effect won't occur until marigolds are grown as a cover crop and then tilled into the soil.

While many gardeners have found companion crops to be useful, other factors such as the local environment can help determine whether a pairing will be successful. The Cornell University Cooperative Extension recommends researching the recommended companions for a particular crop and keeping records on their production to determine what works best together.