Did you know plants have best friends and enemies? Your garden beds might as well be a catty high school cafeteria and you don’t want the potatoes sitting down at the tomato’s table. Ok maybe it’s not quite that bad (maybe I just have too many teenagers running around my house!). But plants do have “friends” and just like human friendships, plant friends help each other grow. This is called companion planting.
Science behind Companion Planting
There are plenty of ways plants can help each other out. Tall plants (like sunflowers) can help shade shorter shade loving plants (like lettuce). Sometimes a companion can deter pests that like to go after their friend. For instance, nematodes love to eat melons, but hate the smell of marigolds so by planting them together you can naturally deter nematodes.
Bean vines attract beneficial insects (like spiders) that like to prey on insects that will eat your corn. Onion’s strong smell can deter many kinds of pests. Some companions can also enhance the taste of plants they are sharing soil with. Basil will improve most plants, but works especially well with tomatoes. Dill & cucumbers are another obvious pairing.
Companion plants could also be plants that compliment rather than compete for resources. Beans help fix soil by adding in extra nitrogen – something that nitrogen loving tomatoes would appreciate. Calendula attracts a wide range of pollinators so makes a great friend for lots of plants that flower like squash and cucumbers.
The entire concept of companion planting just reinforces my belief that your garden is meant to be a diverse mix, not rows and rows of the exact same plant! A great way to showcase companion planting is in a square foot garden – click here to learn about square foot gardening
With every good there comes some bad. There are some plant pairings that you should avoid. Potatoes & tomatoes are both members of the nightshade family and are effected by the same types of blight. Planting them together can contribute to the spread of disease. They also are both heavy nitrogen feeders so they could compete for resources, stunting the growth of both. Carrots planted near tomatoes will have stunted growth due to tomato’s extensive root systems. Onions & beans can also stunt each other’s growth.
Companion Planting Guide for Common Backyard Plants
Following is a guide to some of the most commonly found plants for gardeners. “Friends” are plants that will help that plant, “enemies” are ones that will hinder that plant. They aren’t always the same! A good example is with carrots & tomatoes. When you plant carrots near tomatoes, the carrots will be stunted by the huge root structure of the tomato. But the tomato will grow better & be more flavorful. So carrots are a friend of tomatoes, but tomatoes are an enemy of carrots. Planting flowers like marigolds, calendula, sunflowers & nasturtiums not only make your garden gorgeous and more diverse, they also attract a ton of pollinators and beneficial insects so it’s a great idea to sprinkle them all around!
friends: tomatoes, parsley
enemies: onions, garlic, potatoes
friends: pretty much everyone, but especially tomatoes, asparagus & peppers
friends: beets, cabbage, carrots, cauliflower, corn, cucumbers, marigolds, potatoes, strawberries
enemies: garlic, leeks, onions, shallots
friends: corn, marigolds, potatoes, radishes
enemies: beets, garlic, leeks, onions, shallots
Brassicas (broccoli, Brussels sprouts, cabbage, cauliflower..)
friends: beets, chamomile, dill, mint, rosemary, sage, onions, garlic
enemies: tomatoes, potatoes, eggplant, strawberries
friends: lettuce, onions, peas, radishes, rosemary
enemies: dill, parsnips, tomatoes, potatoes
friends: beans, cucumbers, melons, peas, pumpkins, squash, sunflowers
enemies: tomatoes, celery
friends: beans, cabbage, corn, radishes, sunflowers, marigolds, carrots, dill
enemies: late potatoes
friends: green beans, peppers, potatoes, tomatoes, peas, spinach
friends: cabbage, cane fruits, roses, tomato, celery, lettuce, potatoes, tomatoes
enemies: peas, beans
friends: beets, carrots, parsnips, radishes, strawberries, onions, cucumbers, sunflowers
enemies: cabbage, celery, parsley
friends: corn, marigolds, nasturtiums, pumpkin, radish, squash, sunflowers
friends: apples, beans, cabbage, potatoes, pumpkins, radishes, squash, cucumbers, tomatoes
friends: beets, cabbage, carrots, lettuce, parsnips, dill, strawberries, tomatoes
enemies: beans, peas, asparagus
friends: beans, carrots, corn, cucumbers, early potatoes, radishes, turnip, mint, strawberries, eggplant
enemies: garlic leeks, onions, shallots
friends: basil, carrots, eggplant, onions, parsley, tomatoes, sunflowers
enemies: beans, kale, Brussel sprouts
friends: basil, beans, cabbage, corn, eggplant, marigolds, peas, squash, garlic
enemies: carrots, sunflowers, cucumber, pumpkin, tomato, melons
friends: celery, cauliflower, eggplant, strawberries, peas, beans
friends: bush beans, lettuce, spinach, garlic, onions, peas
friends: cucumbers, squash, pumpkins
friends: asparagus, basil, cabbage, carrots, parsley, onions, rosemary, sage, marigold, corn, beans
enemies: fennel, potatoes, dill, walnut trees