Companion Planting for Raised Beds
Every pair below is included because a specific, documented mechanism exists — pest deterrence, nitrogen fixation, physical support, or documented allelopathy. Vague folkloric associations are excluded. Each entry maps directly to the companion data used by the JoeBees planner.
Good companions (30 pairs)
These pairs produce a documented benefit when planted in the same or adjacent raised bed cells.
Basil helps mask the scent of peppers from thrips and aphids, and shares the same sun + water needs.
Basil's aromatic oils help repel tomato hornworm and whiteflies; both love warmth and the same watering schedule.
Beans fix nitrogen the heavy-feeding corn needs and climb the corn stalks for support.
Beans deter Colorado potato beetles; potatoes deter bean beetles. Mutual pest defense.
Sprawling squash leaves shade soil and deter raccoons; beans feed nitrogen back into the bed.
Borage draws bees and other pollinators to the strawberry flowers and accumulates trace minerals that benefit the patch.
Borage attracts pollinators and predatory wasps, and its leaves deter tomato hornworms.
Chamomile improves brassica flavor and attracts hoverflies that eat aphids.
Dill flowers attract parasitic wasps that prey on cabbage worms.
Garlic deters aphids and cabbage loopers.
Marigolds attract hoverflies that prey on cabbage aphids.
Nasturtiums trap cabbage moths and aphids away from brassicas.
Onion family smells deter cabbage moths.
Rosemary's scent confuses cabbage moths and carrot flies.
Quick-growing lettuce fills space between slow carrots and keeps soil cool and shaded.
Tall tomatoes lightly shade carrots in summer, and carrots loosen soil around tomato roots.
Squash shades the soil around corn, conserving moisture and smothering weeds (Three Sisters).
Radishes deter cucumber beetles, and they mature in 3–4 weeks — long before the cucumber vines spread to fill the space.
Sunflowers offer light shade and act as trellises; their pollen draws pollinators to cucumber flowers.
Garlic helps repel fungal disease and slugs around strawberries.
French marigolds release compounds (alpha-terthienyl) that suppress root-knot nematodes near tomato roots.
Nasturtiums act as a trap crop for aphids and whiteflies, drawing them away from tomatoes.
Spinach grows quickly and is harvested before strawberry runners take over.
Keep apart (14 pairs)
These pairs have a documented negative interaction. Separate them by at least 2 cells (24 in.) in a raised bed.
Brassicas leach calcium and outcompete strawberries for nutrients.
Both are heavy feeders that compete for nitrogen; brassicas can stunt tomatoes.
They share the corn earworm / tomato fruitworm pest. Planting together amplifies infestations.
Fennel releases compounds that inhibit tomato growth — keep fennel in its own corner.
Inclusion criteria
A companion pair is included only when one of the following is documented:
- Volatile aromatic compounds that repel specific named pest species
- Root exudates with documented nematode or pathogen suppression (e.g., marigold alpha-terthienyl)
- Nitrogen fixation by legume root nodules benefiting adjacent nitrogen-demanding crops
- Physical structure providing measurable shelter, shade, or support to a companion
- Trap-crop behavior with evidence of pest diversion
An antagonist pair is included when one of the following is documented:
- Allelopathic chemical release suppressing germination or growth (e.g., fennel sesquiterpenes)
- Shared primary pest or pathogen that amplifies infestation risk
- Allium root exudates inhibiting legume nitrogen-fixation symbiosis
- Documented nutrient competition producing measurable yield reduction
Sources
- Cornell Cooperative Extension — Companion Planting. gardening.cornell.edu
- Old Farmer's Almanac — “Companion Planting Guide.” almanac.com
- Oregon State University Extension — companion planting research summaries.