Bush Bean + Marigold

Bush beans and marigolds are a practical pairing with a specific mechanism: marigolds emit volatile compounds that deter Mexican bean beetle, one of the more persistent defoliators of bush bean plantings. The effect is proximity-dependent, so a solid border around the bean block outperforms scattered interplanting.

Both crops are direct-sow annuals with similar soil preferences: well-drained, moderately fertile ground with a pH around 6.0 to 6.8. Timing aligns naturally in most zones since both go in after last frost and mature within the same general season. Marigolds can be started 4 to 6 weeks early indoors and transplanted at bean-sowing time to have an established border before beans emerge.

The pairing is most useful where Mexican bean beetle pressure is historically high, particularly in the Southeast and mid-Atlantic. In low-pressure regions or where beans are grown in tight rotation, the benefit may not justify the border space. Root-knot nematode suppression from marigolds is sometimes cited, but that benefit requires dense solid-bed planting for a full season prior, not a companion border.