Companion planting that actually works
Separate the folklore from the useful: which plant pairings have a real mechanism behind them.
12 min · intermediate
You will learn
- Identify the mechanisms behind companion benefits
- Use a few evidence-backed pairings
- Avoid pairings that compete for the same resources
Why companions help
The reliable benefits come from physical mechanisms: tall plants shading heat-sensitive ones, dense groundcovers suppressing weeds, flowers feeding the insects that eat your pests, and legumes adding nitrogen as their roots break down.
Pairings with evidence
Basil near tomatoes confuses some moth pests that lay hornworm eggs. Marigolds suppress certain root-knot nematodes, though only some varieties and only in quantity. Lettuce under trellised beans gets shade that delays bolting in early summer.
Antagonists are mostly about competition
Most bad pairings are two heavy feeders fighting for the same nutrients, or one plant shading another that needs full sun. Fennel genuinely suppresses neighbors chemically; keep it in its own pot.
Let the catalog help
Every crop in the plant library lists companions and antagonists from its data. The layout editor flags conflicts when you place plantings side by side, so you can fix clashes before seeds go in.