Why?
Claim. Calendula is said to deter tomato hornworm and aphids. No controlled evidence; calendula itself hosts aphids, and its open flowers do feed hoverflies.
Mechanism. Proposed by tradition; not demonstrated in a controlled comparison.
Conditions. Planted together Both plants must be present at the same time.
Applies when. Optional experiment, not a guarantee.
Limitations. Tradition; insectary value is general.
Evidence. Tier D: Traditional knowledge or structured community observations without a controlled comparison. (tradition).
Sources. University of Minnesota Extension 2023
Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record calendula--tomato--pest_suppression v1. Request a correction.





