Broccoli benefits significantly from companion planting. The plant's main challenges — Cabbage Worm and Cabbage Looper pressure, and the pollination needs that drive fruit set — are directly addressed by the right neighboring plants. Below are the companions with the strongest evidence, their specific benefits, recommended spacing, and the plants to keep broccoli away from.
Companion Planting for Broccoli
Published: April 21, 2026
Best Companions for Broccoli
| Companion | Benefit | Spacing |
|---|---|---|
| Onion | Sulfur compounds repel carrot fly, aphids, and fungal disease | 6 in |
| Garlic | Repels aphids, spider mites, and Japanese beetles; antifungal | 6 in |
| Dill | Attracts beneficial wasps and hoverflies when in flower | 12–18 in (remove before flowering) |
| Rosemary | Repels cabbage moth, carrot fly, and bean beetles | 18–24 in |
| Marigold | Root secretions kill soil nematodes; deters whitefly and aphids above ground | 12 in |
| Celery | Deters white cabbage butterfly; shares similar water needs | 12 in |
Plants to Avoid Near Broccoli
| Avoid | Reason |
|---|---|
| Tomato | Shares nightshade diseases with brassicas; both are heavy feeders |
| Pepper | Shares nightshade disease pressure with brassicas |
| Strawberry | Share verticillium wilt susceptibility with brassicas |
| All Nightshades | Share soil-borne diseases with brassicas; rotate rather than interplant |
Broccoli in a Raised Bed — Layout
In a 4×8 raised bed, plant 6 broccoli at 18-inch spacing in two rows of 3. Surround each plant with onions and garlic at 6-inch spacing — alliums deter the cabbage moths and aphids that devastate brassicas. Add dill at bed corners to attract parasitic wasps that prey on cabbage worm. Never plant tomatoes, peppers, or other nightshades in a broccoli bed; they compete and share disease pressure.
When to Plant Companions with Broccoli
Plant onion with broccoli in the cool-season window — both prefer temperatures in the 55 to 70°F range. Cool-season companions can go in at the same time as direct-sown broccoli (soil at 40°F minimum) or 1 to 2 weeks ahead of transplants. Herb companions like rosemary and chives are perennials that stay in place year-round. Interplant fast cool-season companions (radish, lettuce) between rows for a quick 30 day harvest before the main crop fills in.
Companion Planting & Broccoli Pest Control
Broccoli’s most common pests — Cabbage Worm, Cabbage Looper, Aphids — are directly addressed by the right companions. Onion sulfur compounds repel carrot fly, aphids, and fungal disease. Garlic adds a second defense — repels aphids, spider mites, and japanese beetles; antifungal. These effects are strongest when the companion is planted within 18 inches of the main crop, and when multiple companion species are layered together rather than used singly. Beneficial insects (hoverflies, parasitic wasps, ladybugs) drawn in by companion flowers provide additional control against aphids and caterpillars — flowering companions like dill, borage, and marigold all attract these predators.
Frequently Asked Questions
What is the best companion plant for broccoli?
Onion is the best all-around companion for broccoli — sulfur compounds repel carrot fly, aphids, and fungal disease. Plant onion 6 in from broccoli for the strongest effect. Garlic is a close second — repels aphids, spider mites, and japanese beetles; antifungal.
What should I not plant near broccoli?
Avoid Tomato and Pepper. Tomato shares nightshade diseases with brassicas; both are heavy feeders. Keep these at least 6 feet from your broccoli or plant them in a separate bed to avoid the competition and shared pest pressure.
Can I grow broccoli and tomato in the same garden?
Yes, in separate beds. Tomato and broccoli shares nightshade diseases with brassicas; both are heavy feeders, but placing them 6+ feet apart with a buffer of other crops usually prevents problems. Rotation is also important — don't plant the same family in the same bed two years in a row.
How far apart should companion plants be from broccoli?
Pest-deterrent companions like onion work within 12 to 18 inches of broccoli. Nitrogen-fixing legumes work at 18 to 24 inches. Trap crops (nasturtiums, for example) need 18+ inch spacing so pests congregate on the trap rather than the main crop. Flowering companions for pollinator attraction can be anywhere in the bed — their bee-attracting effect reaches 10 to 20 feet.
Does companion planting help with cabbage worm on broccoli?
Yes, for the specific companions that target Cabbage Worm. Onion and Garlic are documented cabbage worm deterrents and should be planted within 18 inches of broccoli. Companion planting is one part of integrated pest management — combine it with floating row covers during peak cabbage worm season and hand-picking for best results.