Companion Plants for Kale: Aphids Are the Real Problem

Bring in the insects that eat aphids

A kale plant can carry a heavy aphid colony deep in its crown where sprays never reach. The reliable fix is having lady beetles, hoverflies, and parasitic wasps already living in the bed before the colony starts.

Those insects need nectar from small, open, flat flowers. That is the single most useful thing you can plant near kale, and it is well supported.

• Dill and cilantro left to flower: nectar for hoverflies, whose larvae eat aphids by the hundred.
• Nasturtium at the bed edge: a trap crop for both aphids and the cabbage white butterfly.
• Onions and garlic: no room taken, no shared pests, and they overwinter alongside kale.
• Beets and carrots: different rooting depths, so nothing competes with kale's shallow feeder roots.
• Thyme: low aromatic cover along the edge of the bed.

What to keep away

Tomatoes are the main one. Both are hungry crops going after the same nitrogen, and they want opposite weather, so pairing them means one is always in the wrong season.

Strawberries compete at the surface and share some soil trouble in a crowded bed.

Bulb fennel slows the growth of most vegetables planted near it, kale included.

Ignore the charts that put kale and beans at odds. That pairing causes no measurable problem.

What should never follow kale

Kale is a brassica, and the brassica family is the group where rotation matters most. Broccoli, cabbage, cauliflower, Brussels sprouts, kohlrabi, collards, mustard greens, bok choy, turnips, radishes, and arugula all belong to it.

They share clubroot, whose resting spores survive in soil about 7 years, and the cabbage root maggot, which overwinters in the same ground. Neither has a cure once established.

Rotate the whole family as one group and give a bed 3 years before any of them comes back. Kale's long season makes this easy to forget, since a bed can still be full of kale when you are planning next spring.

• Do not follow kale with any brassica, including radishes and turnips.
• Give the bed 3 years minimum before the family returns.
• Plan the rotation while the kale is still standing, or you will forget the bed was used.

What matters more than any pairing

Kale gets sweeter after frost, because cold makes the plant convert starch to sugar. So the timing that matters is planting for fall and leaving it out through the cold, not rushing a spring crop that turns tough and bitter in summer heat.

Harvest from the bottom up, taking the oldest outer leaves and leaving the growing tip, and one plant produces for months. Strip the top and it is finished.

The free planner sets fall planting dates from your own frost dates so the crop matures into the cold that improves it.