Companion Planting: What Works and Why

By Ryan Dorn, SouthernSeeds.com

In the world of gardening, there’s a kind of "dance" happening right beneath our noses and, more specifically, right beneath our plants. It’s called companion planting, and it's a natural phenomenon that's been harnessed by gardeners for centuries. But what exactly is companion planting, and how does it work? Let's dig into it, shall we?

A Friendship Among Flora: Understanding Companion Planting

Companion planting is kind of like setting up a good blind date. You pair up plants that you think will hit it off, in hopes that they’ll benefit each other in the long run. In the plant world, good companions can help each other grow, fend off pests, and even improve flavor. You see, plants, like people, have relationships. Some plants get along great, and others, not so much.

For instance, take tomatoes and carrots. They’re the best of buddies. Plant them next to each other, and they’ll both thrive. But if you try to put cabbage next to those same tomatoes, it’s going to be a no-go from the get-go.

The Mutual Benefits: How Do Companion Plants Help Each Other?

So, how exactly do these plant buddies help each other out? Well, the benefits are numerous and can vary from pair to pair. Some plants, like marigolds, emit certain chemicals that deter pests, essentially acting as bodyguards for their plant pals. Others, like beans, fix nitrogen into the soil, acting like little gardeners themselves, replenishing nutrients for their neighbors.

Five Benefits of Companion Planting: What’s In It for Your Garden?

Companion planting can seem like an advanced gardening skill, but trust me, the benefits are solid and it's worth learning to maximize your success. Here are the top five perks to getting your plants a few good roommates:

1. Pest Control: Some plants deter pests that are attracted to their companions, reducing the need for chemical pesticides.
2. Maximize Space: Companion plants can help each other utilize space more efficiently. For example, tall plants provide shade for shorter plants that require less sun.
3. Weed Control: Dense plantings of companion crops can suppress weed growth by blocking out sunlight.
4. Nutrient Sharing: Some plants, like beans and peas, fix nitrogen in the soil, benefiting nutrient-hungry plants planted nearby.
5. Increased Yield: A well-planned companion planting scheme can lead to increased yield and more efficient use of space.

Unlikely Friends: Best Companion Planting Matches

One of the most classic examples of companion planting is the Native American “Three Sisters” method: corn, beans, and squash. The corn acts as a natural trellis for the beans to climb, the beans fix nitrogen to benefit the corn, and the squash spreads along the ground, blocking weeds and deterring pests. It's a perfect little plant community.

When it comes to companion planting, there isn't a one-size-fits-all approach. It requires a bit of planning and understanding about each plant's needs and characteristics. For example, onions are great pals for most plants, as they deter a lot of pests. But you'll want to keep them away from peas and beans, as they stunt their growth.

Planning Your Garden: How Far Apart Should Companion Plants Be?

When you’re planning your companion plant garden, the same rules of spacing still apply. You’ll need to make sure you’re giving your plants enough room to grow without crowding each other. As a general rule, spacing can range from 12 to 18 inches apart for most vegetables. However, some larger plants, like tomatoes and squash, might need more room. It's all about making sure your plants have the space they need while still being able to benefit from their companions.

Doomed Relationships: What Plants Should Not Be Planted Close Together?

Just like not all people get along, not all plants play nice together, either. Some plants, like potatoes and carrots, should not be planted together because they compete for the same nutrients. Others, like onions and beans, simply don’t get along. Knowing these bad match-ups is just as important as knowing the good ones when planning your garden.

The Proof is in the Plants: Companion Planting Examples

• Asparagus: Good companions are tomatoes, most other herbs basil and parsley, and flowers such as marigolds, asters and nasturtium. The tomatoes repel the asparagus beetle, parsley attracts beneficial insects, and marigolds deter various pests. Don't plant near onions and other members of the allium family such as garlic and chives.

• Basil: Tomatoes, peppers, chives, and marigolds or borage make good companions. Basil helps to repel mosquitoes and flies and is said to improve the flavor of tomatoes. Avoid planting near rosemary, cucumbers and fennel.

• Beans: Corn, cucumbers, tomatoes, lettuce and nasturtiums are excellent companions. The nasturtiums deter beetles and aphids. Do not plant near garlic, onions, chives, leeks, scallions, shallots, peppers, wormwood, fennel, or gladioli.

• Beets: Onions, corn, brassicas, lettuces, and marigolds are good companions. Marigolds deter pests that can damage beets. Avoid planting near pole beans, field mustard, and chard.

• Broccoli: Dill, beets, celery, rosemary, and calendula are good neighbors. They all help deter pests that are attracted to broccoli. Don't plant near strawberries or nightshades such as tomatoes, eggplants and peppers.

• Cabbage: Dill, beans, beets, celery, onions, and chamomile are good companions. Chamomile enhances the flavor of cabbage and attracts beneficial insects. A few doomed relationships will be mustard plants, strawberries, tomatoes and pole beans.

• Carrots: Tomatoes, peas, and marigolds are great companions. Marigolds deter pests that can harm carrots. Avoid planting near dill, celery, parsnips, fennel, or other large root vegetables.

• Chives: Carrots, brassicas, tomatoes and other nightshades, beets, and marigolds are good companions. Chives can deter aphids and other pests. Don't plant near asparagus, beans, peas and spinach.

• Cilantro/Coriander: Anise, dill, legumes, spinach, tomatoes, and marigolds make excellent companions. Cilantro can help repel spider mites. Avoid planting near tomatoes and peppers.

• Corn: Beans, cucumbers, squash, basil, peas, and sunflowers are excellent companions. Sunflowers can provide a windbreak for corn while also attracting beneficial insects. Don't plant near broccoli, brussels sprouts, cabbage, cauliflower, kale, or kohlrabi as well as most heavy feeders.

• Cucumbers: Beans, radish, lettuce, carrots, corn, and nasturtiums are good companions. Nasturtiums deter pests like cucumber beetles. Avoid planting near brassica (cabbage, cauliflower, etc.), sage, melons, fennel and potatoes.

• Dill: Cabbage, corn, onions, celery, beans, kale, lettuce and chamomile are good companions. Dill can help to attract beneficial insects. Don't plant near cabbage, caraway, eggplant, fennel, lavender, peppers, and potatoes. 

• Kale: Aromatic herbs, artichokes, lettuce, onions, peas, potatoes, and nasturtiums make great companions. Nasturtiums help deter pests that are attracted to kale. Other members of the brassica family won't make good companions as they share many of the same pests.

• Lettuce: Carrots, radishes, tomatoes, dill, beets and marigolds are good companions. Marigolds deter many common pests. Avoid planting near cabbages, broccoli, brussels sprouts, cauliflower, kale, kohlrabi and most brassica. They will compete for nutrients and share many of the same pets.

• Mint: Brassicas, peppers, tomatoes and other nightshades (eggplant), and marigolds are good companions. Mint can help to deter cabbage moths. Don't grow mint next to basil, chamomile, lavender, oregano, parsley, rosemary, sage, strawberries and thyme.

• Onions: Lettuce, beets, cabbage, lettuce and chamomile make excellent companions. Chamomile enhances the flavor of onions. Sunflowers can stunt the growth of your onions and should be avoided. Likewise, onions can stunt the growth of asparagus, beans peas and sage.

• Oregano: Peppers, dill, parsley, rosemary, sage, tomatoes, brassica plants, strawberries and marigolds are good companions. Oregano can help to deter many pests. Don't plant with chives, cilantro and mint.

• Parsley: Asparagus, basil, chives, corn, asparagus, oregano, tomatoes, and marigolds are good companions. Parsley can attract beneficial insects. Avoid planting with allium (onion family), carrots which share the same pets, lettuce and mint.

• Peas: Carrots, corn, tomatoes, cucumbers and marigolds are good companions. Marigolds deter pests that can harm peas. Avoid planting near onions and other allium plants. 

• Peppers: Basil, parsley, carrots, radishes, onions, and marigolds are great companions. Marigolds can deter pests that might damage peppers. Avoid beans, brassica (broccoli, cauliflower, etc.) and fennel.

• Potatoes: Beans, corn, spinach, lettuce, basil, parsley and marigolds are good companions. Marigolds deter pests that might harm potatoes. Cabbage, corn and beans and enhance the potatoes flavor. Avoid planting near catnip, chamomile, 

• Radishes: Peas, spinach, tomatoes other nightshades, cucumbers, lettuce, and nasturtiums are good companions. Nasturtiums help deter pests that are attracted to radishes. Avoid planting with hyssop and most brassica which can attract flea beetles.

• Rosemary: Broccoli, beans, carrots, thyme and marigolds make great companions. Rosemary can deter cabbage moths and bean beetles. There's a lot of conflicting advice on companions for rosemary such as whether or not basil and mint are beneficial companions. The truth is that they a bit of both. They have beneficial properties, but their water requirements can conflict next to rosemary. Stay away from cucumbers, pumpkins and tomatoes do not make good companions.

• Sage: Cabbage, carrots, rosemary, oregano, fennel, strawberries, chives, and marigolds are good companions. Sage can deter cabbage moths and carrot flies. Keep away from cucumbers and most alliums (onions).

• Spinach: Strawberries, radishes, other brassicas, and marigolds are good companions. Marigolds deter pests that can harm spinach. Avoid planting near fennel and potatoes.

• Summer Squash: Beans, corn, and nasturtiums are good companions. Nasturtiums help deter squash bugs and beetles. Avoid planting near vining plants.

• Thyme: Cabbage, tomatoes, fennel, rosemary, sage, dill, lavender and marigolds make excellent companions. Thyme can help deter cabbage worms. Keep away from basil, chives and cilantro.

• Tomatoes: Carrots, onions, garlic, asparagus, celery, peas nasturtium, borage and marigolds are the best companions. Marigolds deter various pests that can harm tomatoes. Avoid planting near most brassicas, corn, dill eggplants and potatoes.

• Winter Squash: Corn, beans, peas, dill, cucumber, lettuce and marigolds are good companions. Marigolds deter pests that can harm squash. Keep away from most root crops such as beets, onions and carrots.

And there you have it, the green-thumbed gang! A simple lowdown on the companion planting scene. It's not all about tossing seeds into the soil and hoping for the best. There's a strategy to this gardening game, and companion planting is a big part of it.

Companion planting is nature's way of saying 'teamwork makes the dream work'. Plants have this incredible knack for supporting each other in ways we're just beginning to understand. Whether it's sharing nutrients, providing shade, or even sending pest predators packing, it's clear that some plants just play nicer together.

Of course, this is just the tip of the iceberg - there are so many more companions out there waiting to be discovered in your garden. Experimenting is half the fun, right? So go on, get your gardening gloves on, and start playing matchmaker with your plants!

And remember, if you're ever stumped or have a burning question, don't hesitate to drop us a line. We're here to help you navigate your gardening journey, so don't be a stranger.

Till our next green thumb gossip session, happy gardening, folks!