Companion planting is the practice of growing different plants together for mutual benefit. The research on the benefits of companion planting focuses on vegetable gardens, but ornamentals like roses can also benefit from companion planting to help prevent disease and insect infestation.
Unlike other areas of gardening, companion planting is not always based on hard scientific facts but on observations, the type of garden lore found in farmer’s almanacs. There is always an 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 on 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 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 can provide shade for crops like lettuce that does not do well in the hot summer sun, and they can serve as support for crops that need trellising. Interplanting different crops can help mark garden rows, and distinguish fast germinating plants like radishes from slower germinating plants like lettuce. Proper companion planting can even help suppress weeds.
Companion Planting Mistakes to Avoid
Just as there are plants that make good neighbors, there are plenty of opportunities to plant bad neighbors. Generally, plants that compete because of similar nutrient needs, water, space—aboveground growth and belowground 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 can inhibit the growth of other plants. Fennel is often offered as an example of a poor companion plant that should 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 benefits of planting corn, pole beans, and pumpkins together. The corn provides support for the beans which pull nitrogen from the air to benefit the corn's roots. The pumpkins thrive in the dappled shade of the corn and suppress weeds and keep the ground cooler to conserve water.
Here is a list of popular garden crops with their anecdotal recommended companion plants:
|Garden crop||Companion plants|
|Beans||Broccoli, Cabbage, Carrots, Cauliflower, Corn, Cucumbers, Eggplant, Garden peas, Potatoes, Radishes, Squash, Strawberries, Tomatoes|
|Carrots||Beans, Garden peas, Lettuce, Onions, Tomatoes|
|Cabbage and other cole crops (broccoli, Brussels sprouts, collard greens, kale, kohlrabi, rutabagas, turnips)||Other cole crops, Onions, Potatoes|
|Corn||Beans, Cucumbers, Garden peas, Melons, Potatoes, Squash|
|Cucumbers||Beans, Beets, Corn, Onions, Garden peas, Radishes|
|Garden peas||Beans, Carrots, Corn, Cucumbers, Eggplant, Peppers, Radishes, Spinach, Tomatoes|
|Garlic||Beets, Carrots, Cole crops, Eggplant, Peppers, Potatoes, Tomatoes|
|Lettuce||Corn, Pumpkins, Radishes, Squash|
|Melon and watermelon||Broccoli, Corn, Garlic, Radishes|
|Onions||Beets, Carrots, Cole crops, Lettuce|
|Peppers||Basil, Onions, Okra|
|Potatoes||Beans, Cole crops, Corn, Lettuce, Spinach, Radishes|
|Summer squash/zucchini||Beans, Corn, Garden peas, Radishes|
|Tomatoes||Basil and other herbs, Carrots Cucumbers Squash as part of a three-way companion partnership|
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 like trapping and repelling pests and attracting pollinators and other beneficial insects to increase the biodiversity in your backyard.
Allow some of the herbs to bloom because that’s when they become a real magnet for beneficial insects.
Flowers as Companion Plants
Planting flowers in your vegetable garden does more than create beauty and provide cut flowers. Annuals such as nasturtiums, sunflowers, marigolds, and zinnias, and perennials such as lavender repel pests and attract beneficial insects.