Rhubarb Companion Gardening Guide

Companion planting is a time-tested gardening method that enriches and protects vulnerable crops. Farmers and gardeners plant specific crops near each other in order to deter pests, attract beneficial insects, and stimulate growth.

Companion plants will either help a specific crop grow or will grow better beside a specific crop, and can do many support jobs in the garden:

1. 1. Repel insect pests. Cabbage worms, cucumber beetles, Mexican bean beetles, carrot flies, cabbage moths, spider mites—all kinds of pests can plague vegetable gardens. Many companion plants (like marigold flowers, nasturtiums, catnip, and rue) repel specific pests and should be planted near certain crops to keep them pest-free.
2. 2. Attract beneficial insects. Pollinators like bees and ladybugs can use a little encouragement to visit vegetable gardens and pollinate the crops. Gardeners often plant attractive plants like borage flowers to encourage pollinators to visit.
3. 3. Improve soil nutrients. When crops grow, they take up valuable nutrients from the soil—leaving the gardener to do a lot of work at the end of the season to renew the soil’s nutrients. However, there are many companion plants (like bush beans and pole beans) that add nutrients like nitrogen back into the soil, helping keep other plants healthy and well-fed.
4. 4. Encourage faster growth or better taste. Many companion plants (like marjoram, chamomile, and summer savory) release specific chemicals that encourage faster growth or better taste in the plants around them, leading to quicker and better harvests for home gardeners.
5. 5. Provide ground cover. Plants that spread low across the ground (like oregano) serve as a blanket over the soil, protecting it from the sun and keeping it cooler for plants that need it.
6. 6. Provide necessary shade. Plants that grow tall and leafy (like zucchini and asparagus) can provide welcome shade for sun-sensitive plants beneath them.
7. 7. Serve as markers. When growing slow-growing plants, it can be difficult to tell where the rows will be while you’re waiting for the seeds to sprout. Gardeners often use fast-growing plants (like radishes) interspersed with the slow growers in their rows to delineate where the slow growers will be.

The leaves on rhubarb plants contain a large amount of oxalic acid, which not only makes them highly toxic to humans (always remove and discard before cooking stalks), but a powerful natural insect repellent. As a general guardian, rhubarb is a great companion plant for just about everything in a vegetable garden. Here are just a few examples of good companion plants for rhubarb:

1. 1. Brassicas like broccoli, cabbage, kale, kohlrabi, and cauliflower benefit from rhubarb’s ability to deter whiteflies with its scent.
2. 2. Rhubarb plants likewise protect beans by repelling black fly aphids—and can take advantage of the extra nitrogen beans put back into the soil.
3. 3. Alliums like garlic and onions deter leaf beetles and weevils from destroying the leaves and stalks of young rhubarb.
4. 4. Strawberries and rhubarb are just as good together in the garden as they are in the kitchen: They’re harvested at the same time and don’t compete for nutrients or space. As a living mulch, strawberries also act as ground cover for rhubarb, tamping down weeds.

Consulting a companion planting chart can also tell you how to curb possible infestations. For example, rhubarb, sunflowers, and thistles are all susceptible to curculios, a weevil that bores into cylindrical stalks to lay its eggs, and should not be planted near one another.

Grow your own food with Ron Finley, the self-described "Gangster Gardener." Get the MasterClass Annual Membership and learn how to cultivate fresh herbs and vegetables, keep your house plants alive, and use compost to make your community - and the world - a better place.