What Is Companion Planting?

A Guide to Companion Planting in Your Vegetable Garden

Lettuce and marigolds

Philippe S. Giraud / Getty Images

Companion planting is the practice of growing different plants together. It is mainly used in the context of vegetable gardens but ornamentals such as roses equally benefit from having neighbors they like.

Unlike other areas of gardening, companion planting is not always based on hard scientific facts but rather on observations, the type of garden lore found in farmer’s almanacs.

There is always a strong element of trial and error to see what works for you. However, understanding your garden as a system of biodiversity where plants are all connected and interdependent of each other helps you make better plant choices.

Benefits of Companion Planting

There are numerous benefits to companion planting. Plants can attract beneficial insects and pollinators, deter pests, and thus act as insect repellants. They can fend off predators and undesirable wildlife. Raccoons, for instance, dislike the smell of cucumbers.

Plants also play a role in soil fertility by improving the nutrient supply, availability, and uptake from the soil. Tall plants such as corn provide shade for crops like lettuce that does not do well in hot summer sun, and they can serve as support for crops that need trellising. Interplanting different crops can help marking the rows, especially when combining fast germinators such as radishes, with slower ones such as lettuce. Companion planting helps suppressing weeds.

Fennel is not a good companion for any garden crop
Fennel is not a good companion for any garden crop. dagut / Getty Images

Companion Planting Mistakes to Avoid

Just as there are plants that make good neighbors, there are also no-noes. Generally, plants that compete because of similar nutrient needs, water, space—aboveground and below with their root systems—as well as sunlight should not be planted next to each other.

Crops that are susceptible to the same plant disease, such as blight, should be kept as far as possible from each other to prevent it from spreading. The same applies to pests.

Some crops inhibit the growth of other plants. Fennel is probably the best-known of the poor companion plants that needs to be given its own spot in the garden far away from all other crops.

Companion Planting Chart

Before you even start thinking about companion planting in your garden, make sure that you follow the rules of crop rotation. Don’t plant the same garden crop in the same spot for consecutive gardening years, as this can lead to pest and disease problems, as well as nutrient imbalances.

Depending on the source you consult, information on which plants make good companion plants for each other can vary greatly. There are only a few “hard facts” that are unanimously and universally agreed upon, such as the incompatibility of members of the allium family (onions, garlic, leeks, shallots, scallions, chives) with legumes (beans and peas) because the members of the onion family release a substance to the soil that kills the beneficial bacteria on bean roots. This inhibits their growth and prevents the beans from fixing nitrogen to the soil.

Here is a list of popular garden crops with their recommended companion plants and undesirable neighbors:

Garden crop Companion plants Plants to avoid
Beans Broccoli
Cabbage
Carrots
Cauliflower
Corn
Cucumbers
Eggplant
Garden peas
Potatoes
Radishes
Squash
Strawberries
Tomatoes
Beets
Members of the onion family (onions, garlic, leeks, shallots, scallions, chives)
Peppers
Carrots Beans
Garden peas
Lettuce
Onions
Tomatoes
Dill
Parsnips
Parsley
Cabbage and other cole crops (broccoli, Brussels sprouts, collard greens, kale, kohlrabi, rutabagas, turnips) Other cole crops
Onions
Potatoes
Pole beans
Strawberries
Tomatoes
Corn

Beans
C
ucumbers
Garden peas
Melons
Potatoes
Squash

Tomatoes
Cucumbers Beans
Beets
Corn
Onions
Garden peas
Radishes
Melons
Potatoes
Garden peas Beans
Carrots
Corn
Cucumbers
Eggplant
Peppers
Radishes
Spinach
Tomatoes
Members of the onion family
Potatoes
Garlic Beets
Carrots
Cole crops
Eggplant
Peppers
Potatoes
Tomatoes
Beans
Garden peas
Lettuce Corn
Pumpkins
Radishes
Squash
Cole crops
Melon and watermelon Broccoli
Corn
Garlic
Radishes
Potatoes
Onions

Beets
Carrots
Cole crops
Lettuce

Beans
Peas
Peppers Basil
Onions
Beans
Potatoes Beans
Cole crops
Corn
Lettuce
Spinach
Radishes
Eggplant
Peppers
Tomatoes
Summer squash/zucchini Beans
Corn
Garden peas
Radishes
Potatoes
Tomatoes Basil and other herbs
Carrots
Cucumbers
Squash as part of a three-way companion partnership
Cole crops
Corn
Potatoes
Blooming borage attracts honeybees and other pollinators
Blooming borage attracts honeybees and other pollinators. Paul Starosta / Getty Images

Companion Planting with Herbs

Not every garden is large enough to grow a variety of crops for companion planting. But that does not mean that you cannot take advantage of the numerous benefits that herbs offer—trapping and repelling pests, attracting pollinators and other beneficial insects, thereby increasing the biodiversity in your back yard.

From aphids to tomato hornworms, these are just a few of the culinary herbs that can take care of different pests in your garden, or attract beneficial insects:

  • Basil
  • Borage
  • Chives
  • Cilantro
  • Lavender
  • Mint
  • Oregano
  • Rosemary
  • Sage
  • Thyme

Try to let at least a part of the herb plant grow until it blooms without cutting it because that’s when it will become a real magnet for beneficial insects.

Flowers as Companion Plants

Planting flowers in your vegetable garden does more than creating beauty and providing cut flowers. Annuals such as nasturtiums, sunflowers, marigolds, and zinnias, and perennials such as lavender repel pests and attract beneficial insects.