Onions are one of the all-around best companions for deterring pests. They can help repel cabbage loopers, aphids, and diamondback moths.
Radishes are a useful trap crop for flea beetles, which can eat kale. They'll also be ready to harvest before kale plants need their space.
Lettuces grown with kale will maximize space between plants. It also grows well with other kale companions, like onions and chives.
Marigolds are excellent for repelling most kale pests, and nasturtiums are a good trap crop for nematodes and aphids. Plant marigolds near your kale and sow nasturtiums a short distance away.
Planting oregano and sage with kale can help reduce damage from whiteflies, aphids, beetles, and moths. Flowering oregano also supports beneficial insects that prey on pests.
for more companion planting ideas + what not to plant with kale