Emily ParkerBy Emily Parker

Updated November 2026

Companion planting for cabbage worms can cut the damage to your brassicas without relying on sprays every week. The method works by pairing cabbage, broccoli or kale with plants that either repel the adult white cabbage butterflies, attract the beneficial insects that eat the caterpillars, or simply make it harder for the moths to find your crop. You will finish with a bed layout you can plant this season and a simple routine for checking the leaves.

Understand What Companion Planting Can and Cannot Do

Cabbage worms are the green caterpillars of the cabbage white butterfly and the cabbage looper. The adult butterflies lay single eggs on the undersides of leaves, and the larvae chew holes in the foliage for several weeks. Companion plants will not make a brassica bed completely caterpillar-free, but they can reduce egg-laying and boost the predators that keep numbers down. Pair these plants with hand-picking and row cover for the best results.

Shopping for one? See our guide: Companion Planting with Pole Beans: 5 Best Picks for 2026.

Choose the Right Companion Plants

Several plants are commonly used alongside brassicas for this purpose. Aromatic herbs like dill, thyme, sage and rosemary are often grown nearby because their strong scent is thought to confuse the butterflies. Flowers such as alyssum and calendula attract hoverflies and parasitic wasps, which lay eggs in or feed on caterpillars. Nasturtiums are widely planted as a trap crop, since the butterflies sometimes lay eggs on them instead of on your cabbage. Aim for one or two companions per bed rather than crowding the space.

How to Plant a Cabbage Worm Companion Bed

Good spacing matters more than the number of companions you add. Brassicas need room for airflow, and dense planting can trap humidity and invite other pests.

  1. Space cabbage, broccoli or kale 18 to 24 inches apart, depending on the variety.
  2. Plant alyssum or calendula at the bed edges, about 6 to 8 inches from the nearest brassica, so they draw in beneficial insects without shading the crop.
  3. Sow dill or thyme in gaps between brassica plants, keeping them at least 12 inches away from the cabbage heads.
  4. Plant nasturtiums 3 to 4 feet from the main crop as a trap plant, and check them every few days for egg clusters.
  5. Mulch lightly and water at the base so the flowers and herbs stay healthy and continue to attract predators.

Timing Your Planting

Set out companion flowers at the same time as your transplants or a week earlier. Beneficial insects need flowers blooming when the cabbage white butterflies are active, which is usually late spring through early fall in most US regions. Starting alyssum from seed indoors about six weeks before the last frost gives you blooms in time for the first butterfly flights.

Monitor and Support the Bed

Companion plants work best as part of a routine. Check the undersides of leaves twice a week for the small yellow eggs and for early caterpillars. Remove them by hand, drop them into soapy water, and keep an eye on the trap nasturtiums, pulling and disposing of any that are heavily infested. Look for parasitized caterpillars, which often have small white cocoons on their backs, and leave those in place because they will produce more wasps.

Common Mistakes to Avoid

  • Planting dill or herbs directly against cabbage stems, which can crowd the crop and reduce airflow.
  • Spraying broad-spectrum insecticides, which kill the wasps and hoverflies that control caterpillars.
  • Relying on companions alone and skipping hand-picking when eggs first appear.
  • Letting nasturtiums go unchecked, so they become a nursery for caterpillars that then move onto your brassicas.
  • Planting only one type of companion and expecting full control across the whole season.

Floating row cover is useful because it physically blocks the butterflies from laying eggs on your plants, which companion planting alone cannot guarantee. Look for it by searching View on Amazon. A pair of soft garden gloves makes hand-picking caterpillars more comfortable, and a small bucket of soapy water helps you dispose of them quickly; search View on Amazon for a pair that fits well.

FAQ

Do companion plants completely stop cabbage worms?

No. They reduce egg-laying and encourage predators, but most gardeners still need to check leaves and remove caterpillars by hand. Combining companions with row cover gives the most reliable results.

Which companion plant works best for cabbage worms?

Alyssum and calendula are among the most reliable because they attract the tiny wasps and hoverflies that feed on caterpillars. Nasturtiums are often used as a trap crop to draw butterflies away from brassicas.

Can I plant dill right next to my cabbage?

It is better to keep dill 12 inches or more away from the cabbage heads. It can be grown nearby to help attract beneficial insects, but crowding can reduce airflow and create a more humid environment.

Conclusion

Companion planting for cabbage worms works best when you combine well-chosen flowers and herbs with proper spacing and regular leaf checks. Start with alyssum or calendula at the bed edges, add a trap crop of nasturtiums, and inspect your brassicas twice a week. Pairing these steps with row cover gives you the strongest protection through the season.

Ready to choose one?

Emily Parker

About Emily Parker

Emily Parker is part of our editorial team and reviews and edits our vegetable & edible gardening guides, checking product details against manufacturer specifications and owner feedback.