Why?
Claim. Popular charts say tomatoes and Brussels sprouts (and other brassicas) should not be grown together. In the same field trials that tested basil, tomato–Brussels sprout mixtures behaved like any other mixture: no harmful interaction, just competition that depended on density.
Mechanism. No inhibitory mechanism demonstrated; both are large plants that compete for light, water and nutrients at close spacing.
Studied in. West Virginia, USA; replicated field plots. (field)
Conditions. Planted together Both plants must be present at the same time.
Applies when. Neither reward nor penalty; plan by space, light and water like any two large crops. Note they belong to different rotation groups with different soil-disease risks.
Limitations. One study, one site; the tradition remains widespread.
Evidence. Tier B: One or more relevant controlled field studies or an authoritative synthesis tied to the crop, effect and arrangement. (field trial).
Sources. Bomford 2009; University of Minnesota Extension 2023
Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record brussels-sprouts--tomato--root_competition v1. Request a correction.
