Companion Planting Guide: Best Plant Pairings for a Thriving Garden

Companion planting is one of the oldest tricks in gardening: placing certain plants near each other because they help one another grow, repel pests, or make better use of space. It costs nothing extra and can noticeably improve a small garden's yield.

Why companion planting works

Plants interact with their neighbors in a few concrete ways:

• Pest control — some plants repel insects that damage nearby crops (marigolds deter aphids, basil confuses tomato hornworms)
• Soil improvement — legumes like beans and peas fix nitrogen in the soil, feeding heavier feeders planted nearby
• Physical support — tall plants like corn or sunflowers can act as a natural trellis for climbing beans
• Pollinator attraction — flowers like borage and zinnia draw in bees that also pollinate your vegetables
• Space efficiency — fast-growing radishes can share a bed with slow-growing carrots without competing

Classic companion pairings

Plant	Good companions	Why
Tomato	Basil, Marigold, Carrot	Basil repels pests; marigold deters nematodes
Cucumber	Beans, Corn, Radish	Beans fix nitrogen; radish deters cucumber beetles
Pepper	Basil, Onion, Spinach	Basil repels aphids and spider mites
Squash/Zucchini	Corn, Beans, Nasturtium	Nasturtium is a trap crop for aphids
Lettuce	Carrot, Radish, Strawberry	Different root depths, no competition
Carrot	Onion, Leek, Rosemary	Onion family repels carrot fly
Beans	Corn, Cucumber, Squash	Fix nitrogen for heavy feeders nearby
Onion/Garlic	Carrot, Tomato, Cabbage	Repels most common pest insects

Pairings to avoid

Some plants actively compete or attract shared pests:

• Beans + Onions/Garlic — alliums can stunt bean growth
• Tomatoes + Corn — both attract the same pest (corn earworm/tomato fruitworm — same insect)
• Potatoes + Tomatoes — both susceptible to blight, and can spread it to each other
• Carrots + Dill — mature dill can stunt carrot root development

How to actually plan a companion-planted layout

Knowing the pairings is the easy part — fitting them into an actual plot is where most people get stuck. A few practical rules:

1. Group by water needs first, then refine for companions — a plant that needs daily water next to one that prefers dry soil will fight you all season
2. Put taller plants on the north side of your bed so they don't shade shorter companions
3. Leave room for the fixer crops — a strip of beans or peas along one edge benefits everything else in the bed
4. Rotate yearly — even with good companions, don't plant the same family in the same spot two years running

If sketching this out on paper feels tedious, GrowLocal's garden designer does the companion-checking for you — pick a plot size, drag vegetables onto the grid, and it highlights good neighbor pairings as you place them, so you can see the layout working before anything goes in the ground.

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Companion planting won't fix bad soil or a garden with too little sun, but for a well-planned bed, it's a free yield boost. Start with a couple of proven pairings — tomato and basil, beans and corn — before trying to companion-plant an entire layout at once.