Companion Planting Guide: Best and Worst Plant Pairings (for Fall Gardens)

One of the best-kept secrets in gardening isn’t about fancy tools or expensive fertilizers—it’s about your plants’ companions. Companion planting is all about pairing crops that help each other thrive while keeping pests and disease at bay at the same time.

Some plants are like best friends in the garden, while others are more like rivals competing for space and nutrients. Get these relationships right, and your garden will pretty much take care of itself. If you get them wrong, you might find yourself getting stuck with lackluster harvests. Since fall is approaching, let’s look closer at some of the best and worst plant pairings for this season.

Recommended Plant Pairings

Carrots and Onions
This is a classic duo in the garden. Onions help fend off carrot flies, while carrots don’t mind sharing space. During fall, I like to pluck a row of onions next to my carrots—not only does planting them together save space, but this also reduces pests without any extra effort. 

Lettuce and Garlic
Garlic is the protective neighbor for other plants in the garden. Its strong scent deters aphids and slugs, giving your tender lettuce plant a better chance to thrive.

Spinach and Radishes
These are two fast-growing fall favorites that get along beautifully. Radishes sprout quickly, loosening soil for spinach roots, while spinach shades the ground and helps keep weeds down.

Cabbage and Dill
Plant dill next to your cabbage for added protection, as they attract beneficial insects like ladybugs and lacewings, which prey on cabbage worms. I once had a fall bed of cabbage nearly destroyed by pests until I tried planting some dill next to it. The following season, my cabbage was vibrant and healthy once again.

Pairings to Avoid

Beans and Onions
While both are great crops on their own, beans and onions are terrible neighbors. Onions can stunt bean growth, and beans just never seem to take off when planted nearby. Give them their own space to grow and they’ll reward you with bigger harvests. 

Tomatoes and Brassicas
These heavy feeders will compete for nutrients when put together, leaving both crops stressed. One fall, I tucked kale next to my late tomatoes and both struggled to grow—neither gave me the yield I’d wanted. 

Potatoes and Pumpkins
As potatoes and pumpkins both sprawl and require plenty of nutrients, they just turn into a tangled, unproductive mess when planted together. Keep them far apart from each other, it’s for the best. 

Fall-Specific Tips

Cool-weather crops are the natural choice for fall, and companion planting is also ideal for this time of year. Since days are shorter and temperatures cooler, strategically pairing crops helps maximize space and efficiency.

Before the arrival of the first frost, interplant radishes with spinach for a quick one-two harvest. Try growing garlic near leafy greens to protect them through fall and even into early spring as well. Another tip is to plant herbs like dill and cilantro near brassicas to lure beneficial insects to fend off pests. And don’t forget your cover crops. Pairing clover or vetch in your fall garden beds helps fix nitrogen and sets the stage for healthier soil next spring.

Wrapping Up (for the Season)

Companion planting is a lot like matchmaking for your plants. Some crops encourage others to grow, while boosting flavor and protection, while others compete and hold each other back. By learning the best and worst pairings  and applying them, you’ll not only enjoy bigger harvests but also a healthier ecosystem.

Think of your plants as neighbors. Some will share meals and watch each other’s backs, while others are better kept a few rows apart. Soon enough, you see the advantages of growing plants with companions!