The Top 10 Companion Plants for Your Garden (& 5 Foes)

November 19, 2025

Planning your garden layout is the key to ensuring every plant gets what it needs to thrive—including distance from other plants that might compete for nutrients or attract damaging pests. It’s also worth thinking about which plants can benefit each other.

Certain plants make strong companions for their pest-deterrent properties or their ability to attract beneficial insects. Others help suppress weeds or improve moisture retention in the soil.

If you want to make the most of your garden, learning what plants to pair together (and which pairings to avoid) is critical. Below you’ll find our top recommendations for the best companion plants as well as five plant pairings to avoid.

1. Basil

Good For: Asparagus, borage, chives, peppers, tomatoes

As a companion plant, the main benefit basil has to offer is its ability to deter pests. It actually deters pests in two ways. First, its strong scent can be confusing for pests, serving to distract them away from nearby plants. Basil also directly deters common insects like spider mites, whiteflies, and tomato hornworms. If basil is allowed to flower, it attracts pollinators like bees and butterflies which may help improve the yield of other plants in your garden.

2. Brassicas

Good For: Other brassicas, basil, beans, beets, carrots, celery, collard greens, corn, cucumber, garlic, lettuce, mint, nasturtium, onions, peas, potatoes, radishes, spinach, thyme

Also known as cruciferous vegetables, brassicas are a genus of plants in the mustard family. Examples include cabbage, broccoli, cauliflower, kale, and Brussels sprouts. Many brassicas act as cover crops, spreading across the ground to shade the soil and help retain moisture—this effect may also help suppress weeds. With their deep root systems, brassicas can also help improve soil structure for the plants around them.

3. Carrots

Good For: Beans, chives, leeks, lettuce, onions, peas, radishes, tomatoes, sage, rosemary

As root vegetables, carrots can benefit nearby plants by loosening compacted soil. This improves drainage, allowing more air and water to reach the roots of surrounding plants. Because carrots only have medium nutrient requirements, they’re good companions for heavy feeders like tomatoes. There’s less risk that carrots will outcompete such plants for nutrients than other heavy feeders like brassicas.

4. Corn

Good For: Beans, cucumbers, garden peas, melons, potatoes, squash, sunflowers

With its tall stalks, corn makes a natural trellis for climbing plants like beans and cucumbers. Instead of using stakes or other supports, you can simply grow corn in the same space and get more use out of your garden. Corn can also provide valuable shade for ground-covering plants like melons and squash, helping to retain soil moisture and prevent sunscald.

5. Lettuce

Good For: Beets, carrots, corn, marigold, onions, pumpkins, radishes, strawberries, squash

Lettuce can benefit a wide variety of plants in its role as a ground-cover crop. As it grows, it shades the soil beneath which helps keep the soil cool and reduces moisture loss during hot weather—this makes it a particularly good companion for tomatoes and peppers. The broad leaves also block out sunlight, helping to suppress weed growth along the ground. And because lettuce has a shallow root system, it won’t impede the growth of plants with deep taproots like beets, carrots, and radishes.

6. Marigolds

Good For: Basil, carrots, cucumbers, eggplants, kale, lettuce, onions, peppers, potatoes, tomatoes

Planting marigolds in your garden doesn’t just add a pop of color among the green. These flowers are natural pest deterrents, useful against aphids, whiteflies, and nematodes. Due to their strong scent, they may also deter wildlife like rabbits and deer that might eat your plants. Marigolds also attract beneficial insects like pollinators and predators that feed on pests. French marigolds in particular can help control soil pests like root-knot nematodes.

7. Mint

Good For: Asparagus, beans, broccoli, cabbage, carrots, kale, peas, peppers, tomatoes

Mint is a particularly strong companion plant for other herbs but can also benefit a wide variety of vegetables. Its primary benefit comes from its natural pest deterrent properties. Mint is useful in repelling aphids and spider mites from tomatoes and cabbage moths from brassicas. If allowed to flower, mint may attract pollinators and predatory insects like parasitic wasps and hoverflies. The thing to keep in mind with mint is that it spreads quickly, so it’s best used in container gardens.

8. Nasturtium

Good For: Broccoli, cabbage, cucumber, kale, squash, tomatoes

Not only are nasturtiums edible in their own right, but they can add a pop of color to your garden and serve as beneficial companion plants. They act as a trap crop for insect pests like aphids and attract beneficial insects like pollinators and ladybugs. With their strong scent, they can also be confusing for pests, helping draw them away from nearby plants. If allowed to spread, nasturtiums make good ground cover, helping prevent erosion, retain soil moisture, and suppress weeds.

9. Onions

Good For: Beets, brassicas, carrots, lettuce, peppers, strawberries, tomatoes

Onions are powerful natural pest deterrents due to their strong scent. They’re effective against aphids, carrot flies, and cabbage moths, plus they can mask the scent of nearby plants to keep them from attracting other pests. Another factor that makes onions strong companion plants is the fact that they have different nutrient requirements and unique root systems from many plants, particularly those with long taproots. This means they won’t outcompete nearby plants.

10. Parsley

Good For: Asparagus, basil, beans, corn, onions, peppers, tomatoes

Whereas many companion plants are useful for their pest deterrent properties, parsley excels as an attractant for beneficial insects. The key is letting the parsley go to flower. Parsley flowers attract a wide range of predatory insects like hoverflies, ladybugs, and parasitic wasps. And because it grows fairly low to the ground, it helps retain soil moisture and provides shade to help suppress weed growth.

Beware These 5 Problematic Pairings

Putting certain plants in your garden next to each other could be incredibly beneficial, but there’s also potential for things to go in the opposite direction. Certain plants simply don’t play well together. We won’t overwhelm you with an exhaustive list but, for now, let’s take a quick look at a few of the most problematic plant pairings.

1. Onions and Beans

While planting onions or garlic near certain root vegetables and brassicas can yield positive results, the effects could be disastrous if you plant them near beans or peas. This is because plants in the allium family release chemical compounds into the soil that can interfere with the nitrogen-fixing bacteria on the beans’ roots and stunt the plant’s growth.

2. Tomatoes and Brassicas

Both tomatoes and brassicas (like broccoli, brussels sprouts, cabbage, and kale) are heavy feeders, so planting them too close together could lead to nutrient depletion in your soil. Plus, tomatoes prefer acidic soil while brassicas like their soil on the alkaline side. Outside of container gardening, it’s not practical to use different soil amendments so close together.

3. Potatoes and Cucumbers

Like the previous pairing, planting potatoes and cucumbers together could lead to competition for resources. Both potatoes and cucumbers are susceptible to blight as well, which could increase the risk of one plant spreading it to the other. Finally, the sprawling nature of cucumber plants could interfere with your potato plants getting the sun they need to thrive.

4. Carrots and Dill

The biggest problem with planting carrots and dill too close together is the risk of shared pests. Dill has a strong scent that can attract pests like aphids, spider mites, and carrot rust flies which could spread to your carrots. There’s also some concern with cross-pollination, as both plants are in the Apiaceae family. If carrots and dill flower at the same time, cross-pollination could reduce the quality of that year’s seed (but not the current year’s roots).

5. Fennel and Nightshades

Fennel is an allelopathic plant, which means it releases chemicals into the soil that can inhibit the growth of nearby vegetables. The effect appears to be particularly problematic for plants in the nightshade family like tomatoes and peppers. Fennel has been shown to reduce the yield of tomato plants and shrink the size of peppers.

Final Thoughts

You don’t have to be an expert to cultivate a beautiful and thriving garden—all it takes is a little planning. While companion planting can take your garden to the next level, there’s no need to overthink it. Start with a short list of vegetables you want to cultivate and work from there.

As you develop your gardening plan, you may find that several of the crops on your list can benefit from the same companion plants. Working with the space you have available, you can start to plot the placement of various plants to achieve the maximum benefit.