Kale + Onion

Kale and onion are a practical cool-season pairing. Onion's sulfur compounds deter cabbage moths and their larvae, which are among the more damaging pests on brassicas in spring and fall. Both crops tolerate frost and prefer similar soil conditions: well-drained, moderately fertile, pH 6.0 to 7.0.

Underplanting kale rows with onion sets in late summer or early fall works well because the onions establish while kale is still producing, and both carry through to the first hard freezes. Spacing is rarely a conflict; onions tuck between kale plants without significant root competition at standard kale spacing of 12 to 18 inches.

The pairing is less useful in midsummer heat, when both crops struggle and pest pressure shifts away from cabbage moths. In warm zones, plan this combination for the fall window rather than spring to get the most benefit from the pest-deterrent effect.