Companion planting that's actually useful — print version.
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SUS Farms · Utah Gardening
Companion planting that's actually useful
design · intermediate · ~6 min read
Most companion-planting charts you see online are zodiac-level nonsense. A small handful of pairings have real research backing them, and a few are USU-verified. Skip the woo, keep what works.
Three Sisters (corn + beans + squash)
The most-studied companion system. Corn provides the bean trellis, beans fix nitrogen for the corn, squash leaves shade the soil and suppress weeds. Yields 30%+ more food per square foot than monoculture in research trials.
Basil with tomatoes
Greenhouse studies show basil interplanting reduces thrips and aphids on tomatoes and may boost tomato flavor. Plant 1 basil per 2–3 tomatoes. Anecdotal but well-replicated.
Nasturtium as a trap crop
Aphids prefer nasturtium to almost everything else. Plant a row at the edge of the bed and the aphids cluster there instead of on your kale. Cut and compost the trap crop when colonies get heavy.
Avoid: brassicas next to strawberries
They share fungal diseases (Verticillium wilt) and soil-borne nematodes. Keep them in different bed rotations.
Skip: alleopathic walnut myths
Black walnut juglone IS real, but only matters within a few feet of mature trees. Don't worry about it for typical garden layouts.