The Art of Companion Planting, Part 1: Flowers

Beneficial flowers to keep your garden vegetables and fruits healthy and happy

One of the easiest flowers to grow, cosmos flowers bring in the pollinators, including hummingbirds, and act as a trap crop for aphids.BGStock72/Shutterstock

No plant is an island. The right companion plants can increase yields, keep bugs away, and more. Conversely, the wrong plants can stunt, or even ruin, a crop. One of the best things about companion planting is that it can be as simple or complex as you want it to be.

One of the most famous methods of intercropping is the Native Americans’ “Three Sisters” combination of maize (corn), beans (pole, not bush), and squash. The corn acts as a support structure for the beans to climb. The beans do their part by synthesizing nitrogen from the air and depositing it into the soil in a bioavailable form to fertilize the corn and squash. The large squash leaves, in turn, shade the ground, acting as a living mulch to suppress weeds and help keep the soil moist by inhibiting evaporation.

If that seems a bit much to start with, something as easy as adding the right flowers between your fruits and vegetables can make a huge difference by attracting pollinators while repelling pests.

Marigolds benefit a host of garden vegetables and, as truly "neutral companions," don't bring harm to any. FunFamilyRu/Shutterstock

Marvelous Marigolds

French marigolds are the workhorse of garden flowers. They are hearty, easy to grow, and repel pests such as dreaded tomato hornworms, slugs, cabbage moths, and bean beetles. They also ward off harmful nematodes in the soil.

Tomatoes, bush beans, potatoes, broccoli, squash, eggplant, and kale love them. And even if they aren’t specifically beneficial to the surrounding plants, marigolds are a “neutral companion” plant that will do them no harm.

Calendula (called “pot marigolds,” despite being a different plant genus), are known for their thick roots, which grow in such dense patches that they act as a living mulch. They also repel whiteflies from tomatoes and are a trap crop for aphids, luring them away from your fruits and veggies with their sweet smell.

Borage not only benefits tomatoes, cabbage, squash, and strawberries, but also attracts bees to help pollinate other plants. ioanna_alexa/Shutterstock

Nature’s Buffet

Bees love borage, whose flowers refill nectar at an amazing rate. Tomatoes, cabbage, squash, and strawberries love it too. Borage acts as a trap crop for aphids, luring them away from your edibles, while simultaneously repelling tomato worms and cabbage worms. Its roots aerate the soil, and you can chop the plants up when they’re done and return them to the soil to act as fertilizer—if you don’t nosh on them first. The edible leaves and flowers are high in omega-6 gamma linolenic acid (GLA) and vitamin C.

Another nectary gem is the cornflower. Not only is it a pollinator all-you-can-eat buffet, but it also attracts cutworms and Microplitis mediato, a larval parasitoid of the cabbage moth. Plus, its vibrant blue color lures in birds that eat aphids and caterpillars.

Colorful and playful zinnias are another nectar-rich option. Hummingbirds flock to them. They keep aphids and thrips off melons, repel dreaded Japanese beetles in the garden, and are a great companion plant for asparagus, which takes three to four years before it becomes an adult plant that you can harvest. Zinnias act as a trap crop for the beetles, worms, and flies that are attracted to the young asparagus.

Hummingbirds flock to zinnias, which also serve as a trap crop for beetles, worms, flies, and other unwanted insects. unverdorben jr/Shutterstock

More Versatile Beauty

Nasturtiums send mixed messages, and unlike on a first date, in the garden, this is a very good thing. They attract aphids away from fruits and vegetables (tomatoes, potatoes, and peppers say “thank you!”), while their strong smell repels or confuses cabbage loopers, squash bugs, and whiteflies so they’ll look elsewhere for lunch. They benefit lettuce and greens not only by drawing aphids away, but also by repelling hungry beetles.

Nasturtium roots aerate the soil, and their cascading leaves provide shade to keep the soil cool and moist. This is particularly important when planting carrot seeds, which take a while to germinate and need constantly moist soil during that period. These sprawling plants can take over, but as the buds, flowers, and leaves are edible and it has been traditionally used in healing teas and tonics, you won’t feel bad cutting it back.

One of the easiest flowers to grow, cosmos flowers bring in pollinators, including hummingbirds, and act as a trap crop for aphids. Two of the best colors are white and bright orange because both attract green lacewings, ravenous eaters that feast on aphids, scale, and thrips. Plus, cosmos are a “cut and come again” flower that can make summery bouquets for the table.

The Big Guy

Sunflowers bring a smile to the face, are edible, and make an excellent living support for climbing plants, such as beans, cucumbers, squash, and melons. Plus, they attract insects that dine on cucumber beetles. But keep them away from potatoes, or they will inhibit their growth. And be aware they’re known to attract squirrels, who will then have discovered your other garden bounty.

Flowers in the vegetable garden will please the eye and, ultimately, the palate as well.

Colorful Allies

When it comes to attracting pollinators and helping with pests, flowers reign supreme. Here’s how to maximize their effectiveness.

Group Effort

The first rule in adding flowers to the garden is to plant in clumps rather than single plants. This will make any repelling properties they have more effective and make them easier for both the pollinators and pests you want to “trap” to find.

Pretty as a Picture

Although the main goal of planting flowers in the garden is their companion plant benefits, let’s not lose sight of color, shape, height, and lifespan. Think about what it’s going to look like before tossing out seeds.

Use Natives

Not every flower you plant has to be native to your area, and many of the most popular companion plants probably won’t be, but tossing in a few natives here and there will improve your backyard ecosystem. The National Park Service is ready to help with handy Ecoregion Pollinator Planting Guides at NPS.gov/subjects/pollinators/ecoregional-planting-guide-cards.htm.