Brassicas—cabbage, broccoli, kale, cauliflower, Brussels sprouts, and mustard greens—are staples in many gardens. They are cold-hardy, nutrient-dense, and versatile in the kitchen. Yet they are also pest magnets and heavy feeders that demand thoughtful placement in the garden. Success with brassicas often comes down to understanding which plants support them and which ones compete or attract trouble. This guide explores the best companions for brassicas and the conflicts you should avoid, helping you design healthier, more productive plantings.
Why Brassicas Need Careful Pairing
Brassicas are unique in several ways:
- Heavy feeders: They require high levels of nitrogen and phosphorus, which can stress soil if not balanced.
- Shallow roots: They need steady moisture and are sensitive to competition.
- Pest-prone: Cabbage worms, flea beetles, and aphids love brassicas.
- Distinct chemistry: They release glucosinolates into the soil, which can inhibit some crops but benefit others.
Because of these traits, brassicas thrive when paired with certain companions but suffer when planted near incompatible crops.
Best Brassica Companions
1. Aromatic Herbs
- Dill: Attracts predatory wasps that attack cabbage worms.
- Chamomile: Said to improve cabbage flavor and attract pollinators.
- Sage and Rosemary: Their strong scents confuse cabbage moths and deter pests.
- Thyme: Effective at repelling white cabbage butterflies.
2. Alliums
- Onions, Garlic, Chives, Leeks: Their pungent aromas mask brassicas from pests like aphids and cabbage loopers. Interplanting them in rows or borders provides natural protection.
3. Legumes
- Beans and Peas: Fix nitrogen into the soil, replenishing nutrients that brassicas consume heavily. They are especially valuable when planted nearby or in rotation before brassicas.
4. Leafy Greens and Lettuce
- Lettuce and Spinach: These fast growers fill gaps between slow-developing brassicas, acting as living mulch while not competing heavily for nutrients.
5. Root Crops
- Beets and Celery: Thrive alongside brassicas without competing heavily for nutrients. Celery also helps repel cabbage moths with its fragrance.
- Radishes: Mature quickly and act as a trap crop for flea beetles, sparing cabbage and kale leaves.
6. Flowers
- Marigolds: Repel nematodes and attract beneficial insects.
- Nasturtiums: Serve as a trap crop for aphids and flea beetles while adding edible flowers to the garden.
- Calendula: Draws predatory insects that feed on aphids and caterpillars.
Plants to Avoid Near Brassicas
1. Nightshades
- Tomatoes, Peppers, Eggplants, Potatoes
Brassicas and nightshades compete for similar nutrients, especially nitrogen, leading to weaker growth for both. Potatoes, in particular, are poor neighbors as they encourage soil-borne diseases that brassicas are vulnerable to.
2. Strawberries
Strawberries and brassicas stunt each other’s growth. Strawberries may also attract pests like slugs, which damage tender brassica leaves.
3. Grapes
Grapevines suffer when brassicas are planted nearby. Ancient gardening wisdom suggests the two are incompatible, and modern gardeners confirm reduced vigor when grown together.
4. Pole Beans
While bush beans can support brassicas, pole beans climb aggressively and compete for sunlight and space, creating conflicts in small gardens.
5. Other Brassicas
Planting too many brassicas together in the same bed compounds pest pressure. Cabbage moths, flea beetles, and aphids can wipe out entire plantings if hosts are too concentrated. Diversifying with companions is essential.
Rotation Matters
Brassicas should never be planted in the same soil two years in a row. Their heavy feeding habits deplete nutrients, while diseases like clubroot linger in soil for years. Rotate with legumes, root crops, or leafy greens to restore balance. Cover crops such as clover or rye between brassica plantings also rebuild soil fertility.
Sample Brassica Companion Planting Combinations
Combination 1: Cabbage with Alliums and Dill
- Cabbage as the main crop.
- Onions in border rows to repel pests.
- Dill interplanted to attract beneficial wasps.
- Result: Reduced cabbage worm pressure and improved yields.
Combination 2: Kale with Beans and Nasturtiums
- Kale in central rows.
- Bush beans beside kale to fix nitrogen.
- Nasturtiums trailing along the bed edges as trap crops.
- Result: Soil fertility boost and flea beetles diverted from kale.
Combination 3: Broccoli with Lettuce and Chamomile
- Broccoli as the main structure.
- Lettuce filling gaps, serving as groundcover.
- Chamomile nearby to enhance broccoli’s flavor.
- Result: Efficient use of space and natural flavor improvement.
Tips for Growing Brassicas with Companions
- Stagger planting: Sow fast crops like radishes and lettuce between brassicas to maximize space and minimize weeds.
- Mulch generously: Brassicas need steady moisture; mulch helps retain water and reduce stress.
- Use trap crops: Plant radishes or nasturtiums as sacrificial plants to lure pests away.
- Encourage predators: Include flowering herbs and calendula to support ladybugs, lacewings, and parasitic wasps.
- Avoid overcrowding: Brassicas need airflow to prevent fungal disease. Companions should be thoughtfully spaced.
Common Mistakes to Avoid
- Planting brassicas with heavy feeders: Pairing with nightshades or corn depletes soil rapidly.
- Overloading brassica beds: Growing multiple brassica varieties together invites pests.
- Skipping rotation: Clubroot and other diseases persist for years if brassicas return too soon.
- Neglecting soil prep: Brassicas demand fertile, well-drained soil; without compost or amendments, even the best companions won’t help.
FAQs on Brassica Companions and Conflicts
What are the best overall companions for brassicas?
Alliums, legumes, aromatic herbs, and flowers like marigolds and nasturtiums are the most reliable brassica companions.
Can brassicas grow next to root vegetables?
Yes. Carrots, beets, celery, and radishes coexist well with brassicas and even enhance soil use efficiency.
Why shouldn’t I plant tomatoes near cabbage or broccoli?
Both crops are heavy feeders. Together they deplete soil quickly, leading to weaker yields and greater disease susceptibility.
How do I manage pests without chemicals?
Use trap crops like radishes, deterrent herbs like thyme, and predator-attracting flowers like calendula. A mixed companion system reduces pest outbreaks naturally.
Can I grow multiple brassicas in the same bed?
You can, but it’s risky. Planting cabbage, kale, and broccoli together intensifies pest pressure. Interplanting with herbs, legumes, and flowers provides a protective buffer.