Plan · field guide
Companion Planting: What the Research Actually Supports
Companion planting charts promise that the right plant pairings stop pests and boost growth. The truth is most of those charts are folklore, copied from one site to the next with no source. A few pairings do hold up. Here is what the research supports, and what to stop worrying about.
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Most charts are folklore
The classic 'plant X with Y, never with Z' charts are mostly untested tradition. Different charts contradict each other, and few cite any study. So if you have been losing sleep over a pairing rule, you can relax. Getting the basics right matters far more.
What actually holds up
A handful of pairings have real support:
- The Three Sisters: corn, pole beans, and squash genuinely help each other. Corn gives the beans a pole, beans add nitrogen, and squash shades out weeds.
- Flowers for bugs: marigolds, alyssum, and similar flowers draw pollinators and beneficial insects that eat pests.
- Shade partners: tall crops can shade lettuce and spinach to keep them from bolting in summer heat.
- Keeping relatives apart: do not plant tomatoes where potatoes just grew. Same family, same diseases, which is really crop rotation.
What does not hold up
Most 'these two hate each other' rules do not survive testing. Basil next to tomatoes will not change your yield much, though it does no harm and saves garden space. Treat the elaborate enemies-and-friends charts as fun folklore, not planting law.
What matters more than any chart
Four basics beat every companion rule combined: right spacing for airflow, 6 to 8 hours of sun for fruiting crops, healthy soil with compost, and rotating crop families each year. Nail those and your garden thrives no matter what grows next to what. The planner handles the spacing and timing so you can focus on the basics.
Keep going
Questions, answered straight
A few pairings do, like the Three Sisters and flowers that attract beneficial insects. Most chart pairings are untested folklore. Spacing, sun, soil, and rotation matter far more.
Planting corn, pole beans, and squash together. Corn supports the beans, beans add nitrogen, and squash leaves shade the soil and suppress weeds. It is the best-supported companion combo.
You can. It saves space and does no harm, though it will not noticeably boost your tomato yield. The bigger wins are even watering, good spacing, and full sun.
Avoid planting members of the same family in the same spot year after year, like tomatoes after potatoes, because they share diseases. That is crop rotation, the one 'avoid' rule with strong backing.
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