Companion Plants Every Gardener Should Know

Estimated reading time: 8 minutes

Companion planting takes advantage of the symbiotic relationship that some plants have with each other when planted in close proximity. Symbiotic means the plants help each other in unique ways.

This symbiosis could be the way plants help each other, protect each other, or provide other benefits like attracting pollinators or repelling insects or pests like mice and rabbits. It’s all about taking the time to think about how plants can be planted strategically for mutual benefit.

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The 3 Sisters Example

An ancient companion planting idea is defined as the three sisters. It involves planting corn, pole beans, and squash in a cluster.

The idea is that as the corn grows tall, the pole beans use the corn stalks to grow up and around the stalks. The beans return nitrogen to the soil feeding the corn. Corn is a heavy feeder and draws many nutrients from the soil, but the beans compensate as they grow up the corn stalks and return nitrogen to the soil.

The squash planted below have wide leaves that shield the soil from the sun to keep it moist. All three plants, when grown together in close proximity, provide unique benefits as companions. That’s the fundamental benefit of companion planting, but as we go on we’ll find more.

The Companion Planting Heroes

Beans and peas are the heroes when it comes to companion planting. Bush beans, pole beans, and all varieties of peas return nitrogen to the soil, and that’s the critical plant food for all plants.

Beans and peas have a unique way of using something called “nitrogen fixing bacteria” to manufacture excess nitrogen and return it to the soil. If you only companion plant one kind of plant, make it beans and peas.

The plants that tend to be the worst companions fall in the allium family. These include onions, shallots, and garlic. Think twice about where you plant these garden staples. They do a good job of repelling rodents and garden pests, but make bad companions for many flowers and vegetables. They not only inhibit their growth but also repel pollinators that some vegetables need to bear fruit.

Here’s a chart that identifies good companions and some that don’t get along so well. The more you create a good neighborhood for your plants, the more likely you’ll find success in your garden.

VEGETABLE OR FRUIT	BEST COMPANIONS	WORST COMPANIONS	BENEFIT OF PLANTING
Asparagus	Tomatoes, basil, strawberries, peas, carrots, cucumbers	Onions, garlic, leeks, potatoes, all beans,	Not a good companion for many plants
Beans (Pole and Bush Beans)	Brassicas, carrots, celery, chard, corn, cucumber, eggplant, peas, potatoes, radish, and strawberries	Chives, garlic, leeks, and onions	Nitrogen fixing bacteria in the roots return nitrogen to the soil
Beets	Carrots, onions, garlic, lettuce	Pole beans, mustard greens,	Carrots and beets are a classic combination
Broccoli	Celery, potatoes, onions, most herbs	Tomatoes, eggplant, lima beans, pole beans, peppers, snap beans, squash, strawberries	Best if planted in a corner of the garden
Cabbage	Onions, carrots, lettuce, beets, celery, mint, beans,	Tomatoes, radish, spinach, cauliflower, broccoli, grapes, squash, strawberries	Plant along edges and shade tolerant
Carrots	Lettuce, leeks, beans and peas, cilantro, chives, onions, radishes	Celery, parsnips, fennel, potatoes, dill	Typically get along with most common vegetables
Cauliflower	Beans, celery, onions, beets, broccoli, brussels sprouts, char4d, spinach, cucumber, corn, radish	Peas, strawberries, tomatoes	Avoid companion planting beans if also companion planting onions next to cauliflower
Corn	Beans, peas, cucumber, squash, melon, lettuce, tomato and dill	Tomatoes, fennel, asparagus	Heavy feeder and should be rotated with beans or peas season to season
Eggplant	All beans and peas, spinach, tomatoes, peppers	Zucchini, corn, fennel,	Fennel often shows up as a poor companion to most plants
Fennel	Nothing	Everything	Grow fennel in isolation. It does not get along well with others
Herbs in general	Asparagus, tomatoes	Most root vegetables	Herbs are best if simply grown in a dedicated herb garden
Peas	Beans, carrots, celery, corn, cucumber, eggplant, parsley, peppers. potatoes, radish, spinach, strawberries and turnips	Onions	Nitrogen fixing bacteria in the roots return nitrogen to the soil
Peppers	Tomatoes, carrots, basil, chives, fava beans, garlic, spinach, most herbs, all onions	Broccoli, cauliflower, cabbage, fennel, corn, potatoes, eggplant, strawberries	A member of the Nightshade family and prefers other Nightshades like tomatoes
Potatoes	Beans, cabbage, Brussels sprouts, cauliflower, horseradish, lettuce, peas, spinach, radish	Carrot, cucumber, eggplant, fennel, okra, onion, pepper, pumpkin, raspberry, squash, tomatoes, turnips	Potatoes are heavy feeders and one of the worst companions for many vegetables and fruits. Best grown in isolation.
Pumpkin	Beans, peas, corn, radish, lovage,	Fennel, sweet potatoes, white, red and yellow potatoes	Also provides shade for the ground
Radish	Lettuces, tomatoes, carrots, onions, peppers, peas, cucumbers and spinach as well as herbs like dill, mint and oregano	Broccoli, cauliflower, cabbage, potatoes, turnips	Avoid cruciferous vegetables like broccoli, cauliflower and cabbage around radishes
Squash	Peas, beans, radishes, chives, borage, chamomile, sunflower, savory,	Potatoes	Provides shade to hold in ground moisture
Strawberries	Lettuce, chives, leeks, onions, garlic, spinach, asparagus	Tomatoes, eggplant, potatoes, pepper, melons, squash, cucumber, okra, kale, cauliflower, brussels sprouts	Strawberries often show up as a poor companion for many vegetables
Tomatoes	Asparagus, carrot, celery, garlic, onions, chives, lettuce, lovage, radishes, and most herbs	Broccoli, cabbage, cauliflower, corn, fennel, potatoes	Tomatoes are also heavy feeders and should be planted with special attention to companions
Turnip	Broccoli, cauliflower, brussels sprouts, garlic, peas and beans, most herbs	Potatoes, onions	Fairly tolerant of most plants

How to Plan a Companion Planting Layout

Even with a companion chart, knowing how to arrange your plants in your bed makes the difference between success and confusion.

Here are some practical steps:

1. Start with a Garden Map – Draw a rough outline of your garden space (even on graph paper). Mark fixed structures like trellises or paths.
2. Assign Main Crops First – Decide on your major vegetables (tomatoes, squash, beans, lettuce, etc.). These are your anchor plants.
3. Add Companions Based on Function
   • Pest deterring plants: such as marigolds, nasturtiums, or calendula at borders.
   • Pollinator attractors: flowers like cosmos, zinnias, or alyssum near crops that need pollination.
   • Soil enhancers: legumes like peas and beans for nitrogen fixing around heavy feeders (corn, squash).
4. Think Vertically and Horizontally – Place tall plants (corn, sunflowers) on the north side of beds so they won’t shade smaller neighbors. Low‑growing or trailing plants (radishes, lettuce, squash) go on the south and east sides for sun.
5. Group by Water Needs – Place plants with similar moisture needs together to make irrigation easier and more efficient.
6. Leave Room for Rotation & Succession – Plan paths and space so that after harvest you can rotate crops into new sections next season — this helps prevent disease build‑up.

But of Course, There’s More

Some plants repel insects and rodents. Others attract pollinators. Companion planting goes beyond adding nitrogen to soil or protecting soil from the sun’s heat. Here are some flowers and plants to repel pests and attract those bees and other insects to keep everything growing.

The Good Guy Insects (Pollinators)

If you can attract pollinating insects to your garden, you’ll give those low-lying squash blossoms a better chance of getting pollinated. In an environment where bees are dying everywhere, we sometimes need to depend on other pollinators like wasps, yellow jackets, and even butterflies to get a crop.

Then again, honeybees still show up and will show up even more if you give them a reason to visit. Here are some facts to ponder when it comes to pollination:

• All species of bees pollinate 80 percent of all flowering plants on the planet. If you don’t have a local beehive, think about growing flowering plants.
• A single bee colony can pollinate some 300 million flowers and vegetables a day.
• Bees pollinate 70 of the top human food crops.
• One out of every three bites of food we eat is derived from plants pollinated by bees and other pollinating insects.
• Avocados, apples, pears, peaches and cherries are 90% dependent upon bee or insect pollination.
• Cucumbers, squash, apples, peppers, tomatoes and berries are other food crops that rely on flying insect pollination.

The Good Guy Plants

Some plants repel rodents and bad bugs. They look nice in any garden and keep the bad guys away. Here are the heroes that you can plant In or around any garden that can both serve and protect from rodents, bugs, and other pests while attracting pollinators:

These pollinator attractors are usually planted around the perimeter of a garden or in close proximity to the garden plot. You just want to get those flying bugs in the area, and they’ll figure out how to do the rest.

It’s another companion planting idea that helps any garden be more productive with the added benefit or repelling the bad guys. In fact, here are the heroes when it comes to garden defense.

The Defenders

There are plants that repel both bad bugs and garden pests like rabbits, mice, and other rodents. Marigolds top the list in addition to daffodils, geraniums and many herbs from rosemary to green onions. Most make good companions but keep an eye on things. If they don’t seem to be getting along, change the neighborhood.

The telegram here is simple: Herbs are the best defenders for a vegetable garden. Plant them around the perimeter or your garden. Some are perennial and some reseed themselves. All of them repel insects, rodents, and other garden pests and most are good companions to all vegetables or flowers.

Here are the heroes:

1. Basil
2. Calendula
3. Catnip
4. Lavender
5. Marigolds
6. Mint Plant
7. Nasturtiums
8. Rosemary
9. Sage
10. Savory
11. Thyme
12. Zonal Geraniums

Common Companion Planting Mistakes

Companion planting is powerful, but beginners often fall into a few traps:

❌ Planting Everything Too Close Together: Companion planting doesn’t always mean crowding. Even beneficial plants need adequate spacing so they don’t compete for light or nutrients.

✔ Tip: Follow spacing guides from seed packets and adjust as plants grow.

❌ Assuming All “Good Neighbors” Always Work: Some popular pairings (e.g., tomatoes + cabbage) can create unintentional competition or attract the same pests. Not all companion claims are backed by research.

✔ Tip: Test small areas first and observe pest or growth trends before applying widely.

❌ Neglecting Crop Rotation: Planting the same companions in the same spot year after year can still lead to soil depletion or disease cycles.

✔ Tip: Rotate families of plants (e.g., nightshades, brassicas, legumes) each season.

❌ Forgetting Beneficial Insects Need Support: Simply planting flowers isn’t enough if there’s no continuous bloom throughout the season.

✔ Tip: Mix early, mid, and late‑season bloomers so pollinators and predators are present all season long.

Take Notes

Any garden is an experiment. Keep a journal and take notes about how your gardens grow. There are many variables that can affect growth, health and yields.

If you keep track of some of the basics, including a simple garden plot of where you planted things and the results, you can make better decisions for future plantings and continue to make companion planting a part of your overall garden strategy.

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