Gardening is a widely enjoyed hobby today, but for most of the past 12,000 years, it was less about leisure and more about survival. Not growing enough food meant hunger, or worse; needless to say, this was a strong motivator for understanding plant growth.
Because of this, our ancestors developed practices such as crop rotation and the use of manure as fertilizer. They also came to realize that some plants simply grow better when paired together. Today, we call that companion planting, and it’s something that every gardener should know. If you’re not already familiar with companion planting, here’s a brief introduction.
What Is Companion Planting?
In school, many of us learned about the Native American practice of growing “the Three Sisters” — corn, beans, and squash — together. It’s a classic example of companion planting. The tall, straight cornstalks support the beans’ vines as they grow, the sprawling squash’s broad leaves choke out weeds, and the beans’ ability to enrich the soil with nitrogen helps nourish the corn and squash.
That’s what companion planting is all about: identifying mutually beneficial plants and growing them together. There are a number of ways that plants can help each other out. A few examples include:
• “Fixing” nitrogen in the soil; select crops form a symbiotic relationship with Rhizobium bacteria to pull nitrogen from the air and turn it into natural fertilizer.
• Loosening and aerating your soil.
• Deterring common pests.
• Luring pests away from prized garden plants by offering alternatives that are even more attractive to them (this is called trap cropping).
• Attracting pest predators.
• Weed suppression, as squash does in the “Three Sisters” example.
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A Beginner’s Companion Planting Guide
There are a lot of plants that are known to work well in companion planting. You can get more detailed lists from your local extension service, nurseries, and garden centers, or in gardening magazines and seed catalogs.
Let’s look at a few of the most popular things gardeners grow and which plants are good companions for them.
Companion Plants for Tomatoes
Nothing beats the taste of a homegrown tomato, which is why so many of us tend to them. Common companion plantings for tomatoes include basil, sunflowers, carrots, chile peppers, dill, and onions. One important tip: Sunflowers draw stink bugs away from tomatoes, but you’ll need to plant them early enough that they bloom when protection is needed.
Companion Plants for Strawberries
Strawberries pair well with beans, lettuce, onions, and spinach. They also thrive alongside herbs such as thyme and borage, which deter pests and attract pollinators.
Companion Plants for Peppers
All peppers, from sweet, fleshy bell peppers to the most searing-hot chiles, benefit from the same set of companion plants. These include basil, cilantro, onions, spinach, and tomatoes.
Companion Plants for Cucumbers
Appropriate companion plantings for cucumbers include beans, peas, corn, lettuce, radishes, sunflowers, and brassicas such as broccoli and cabbage.
Companion Plants for Brassicas (Broccoli, Cauliflower, Cabbage, etc.)
Most of the brassicas — the family that includes broccoli, cauliflower, kale, Brussels sprouts, and cabbage — do well when planted near beans, onions, lettuce, and herbs such as dill and sage. Because it’s such a broad family, not all of these pairings are compatible with every brassica, so double-check which ones are best for your specific situation.
Companion Plants for Carrots
Carrots work happily with companion crops including beans, lettuce, onions, peas, and tomatoes, as well as rosemary and sage. Because they’re slow-growing and a relatively late crop, it makes sense to pair them with early-yielding plants such as peas.
A Few Final Tips About Companion Planting
Before you start digging, there are a few other things you need to know about companion planting. One is that not all companions are necessarily herbs or vegetables. While sunflowers have been the only flower mentioned thus far, many others effectively deter pests or attract predators. For example, strong-scented marigolds can be planted around broccoli and kale to help keep cabbage worms and other pests away, while nasturtiums and zinnias attract beneficial insects that eat harmful ones.
Something else to keep in mind is that companion planting can also have negative effects. Some popular crops (corn and tomatoes, for example) don’t pair well together at all. As a general rule, it’s beneficial to separate closely related crops, such as broccoli and cabbage, or carrots and dill or parsley. Their similarities lead to high competition, and planting them too closely can also create a “target-rich environment” for pests — that’s the opposite of what you want.
