What Is Companion Planting?
Companion planting is the practice of growing different plants in proximity to benefit one another. The benefits can include natural pest deterrence, improved pollination, better use of space, and even enhanced flavor. It's one of the oldest gardening techniques in the world — and one of the most practical for any home garden.
How It Works
Plants interact with each other in several ways:
- Pest confusion: Strong-smelling plants like basil or marigolds mask the scent of neighboring vegetables, making it harder for pests to find their target.
- Attracting beneficials: Flowers interspersed with vegetables draw in pollinators and predatory insects that eat aphids and other garden pests.
- Soil improvement: Legumes (beans and peas) fix nitrogen from the air into the soil, feeding nearby heavy feeders like corn or squash.
- Physical support: Tall plants can shade moisture-loving neighbors or provide structure for climbers.
The Classic Three Sisters
The most famous companion planting combination is the Native American "Three Sisters" — corn, beans, and squash. Each plays a role:
- Corn grows tall and provides a trellis for beans to climb.
- Beans fix nitrogen, feeding the heavy-feeding corn and squash.
- Squash sprawls along the ground, shading out weeds and retaining soil moisture with its large leaves.
This trio planted together produces more food per square foot than any of them planted alone.
Companion Planting Quick Reference
| Plant | Good Companions | Bad Companions |
|---|---|---|
| Tomatoes | Basil, carrots, marigolds, parsley | Fennel, brassicas, corn |
| Beans | Carrots, cucumbers, squash, corn | Onions, garlic, fennel |
| Carrots | Leeks, onions, rosemary, tomatoes | Dill, parsnips |
| Cucumbers | Beans, dill, nasturtiums, radishes | Aromatic herbs, melons (space concerns) |
| Brassicas (cabbage, kale, broccoli) | Dill, chamomile, beets, celery | Strawberries, tomatoes, peppers |
| Peppers | Basil, carrots, onions | Fennel, brassicas |
Flowers That Work Hard in the Vegetable Garden
Don't underestimate flowers as companions:
- Marigolds: Deter nematodes in the soil and confuse above-ground pests. Plant around tomatoes, peppers, and cucumbers.
- Nasturtiums: Act as a trap crop for aphids — pests go to nasturtiums instead of your vegetables. Also edible.
- Borage: Repels tomato hornworm and attracts pollinators. Leaves are edible and taste faintly of cucumber.
Tips for Getting Started
- Start with one or two proven combinations rather than overhauling your entire garden at once.
- Keep notes on what you plant where — companion planting success builds over multiple seasons of observation.
- Don't forget spacing — companions still need adequate room to grow and proper air circulation.
- Interplant herbs throughout your beds; most repel pests and double as culinary staples.
Companion planting won't replace all pest management, but it's a powerful, chemical-free layer in any productive garden. Over time, a thoughtfully planted garden practically manages itself.