Companion planting offers many benefits, but pest management is the most relevant when growing brassicas. Almost every companion plant broccoli has can help reduce damage from one pest or another, and a few can act as trap crops to lure pests away from broccoli.
Pests like cabbage loopers and diamondback moths affect brassica growers around the world, so there's a lot of research into how companion planting with broccoli can keep those pest populations in check. Read on for how to interplant vegetables, herbs, and flowers with broccoli for healthier harvests this year.
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Benefits of companion planting with broccoli
Companion planting with broccoli can help improve your broccoli harvest, but it can also improve your soil and overall garden health. Here's how:
- Providing shade: Broccoli plants grow tall and wide, allowing them to provide shade for cool weather plants like radishes and lettuces in the summer.
- Covering soil: Planting smaller crops between your broccoli plants can help shade the soil, improving water retention and suppressing weeds.
- Maximizing space: Growing root crops with broccoli plants can make the most of a small garden space, as they won't compete with broccoli for nutrients.
- Deterring pests: Many broccoli companion plants actively deter pests. Others send out strong aromas that mask the broccoli and prevent pests from finding it. Still others can be planted as trap crops to lure pests away from broccoli.
- Attracting beneficial insects: Most of broccoli's companions attract insects that prey on pests, like hoverflies, lacewings, ladybugs, and parasitic wasps and flies.
Using multiple companion plants that offer different benefits can be a great strategy for reducing pest damage on broccoli and creating an overall healthier garden. For example, using both a trap crop (to pull pests away from broccoli) and a pest-deterring companion is one of the best methods of pest management available to organic growers.
The best broccoli companion plants
Plants that grow well with broccoli usually enjoy its growing conditions: full sun and rich, well drained soil. There are some exceptions to that rule, like onions and rosemary. In those cases, the companion plants offer enough benefits that it may be worth growing them in sub-optimal conditions to improve the broccoli-- or growing them in a neighboring pot.
For the most part, these companions can be interplanted with broccoli or in rows parallel to broccoli. As long as they are planted right next to each other, they'll have some effect.
Here are a few good companions to plant next to broccoli:
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1. Onions
Growing onions with broccoli is thought to improve the broccoli's flavor, but this pairing will also make efficient use of space. Most importantly, there's evidence that onions may reduce damage from cabbage loopers, diamondback moths, and aphids-- all common broccoli pests.
Read More: The 20 Best Companion Plants for Onions
2. Garlic
Like other alliums, garlic's strong aroma makes it useful for repelling and confusing pests. Specifically, interplanting broccoli with garlic may reduce diamondback moth damage. Garlic may also help deter common pests like aphids and thrips. Growing garlic alongside broccoli also helps maximize space.
3. Lettuce
Like broccoli, lettuces are hungry and thirsty plants. They'll enjoy the soil at the base of taller growing broccoli plants, which will give them shade and help extend their harvest into the summer. Lettuces aren't particularly useful for repelling pests, but they will grow quickly, keep the soil covered, and suppress weeds.
Read More: 8 Easy-to-Grow Summer Lettuce Varieties
4. Radishes
Radishes planted with broccoli can act as a trap crop for flea beetles. If you struggle with defoliation from flea beetles, this is one of the best organic solutions available. Otherwise, you can grow radishes as a catch crop between broccoli plants. Radishes germinate and mature much more quickly than other brassicas, so they make efficient use of space while young broccoli plants are getting established.
5. Rosemary
Rosemary offers a host of benefits to its companion plants. It's known to repel cabbage loopers, repel whitefly, deter thrips, deter green peach aphids, and repel armyworms. In fact, rosemary is one of the best herbs for companion planting-- but it can be a challenge to grow it in the same soil as vegetables.
Broccoli likes more water than rosemary, so you may see the best results from placing potted rosemary next to broccoli plants. To plant rosemary with broccoli, prepare a very well draining soil with added compost but without composted manure or other fertilizers. Excess nitrogen in the soil will harm both plants, so it's ideal to plant them into soil that's just been evacuated by a heavy feeding vegetable like tomatoes or cucumbers.
Read More: The 11 Best Companion Plants for Rosemary
6. Sage
Sage may help repel flea beetles, cabbage moths, and diamondback moths. Combined with a trap crop like radishes and other pest-repelling companions like marigolds or rosemary, planting sage with your broccoli could help reduce pest damage and improve yields.
7. Thyme
Thyme may be among the best herbs for reducing pest damage in cruciferous vegetables like broccoli, cabbage, and cauliflower. Its aroma is lauded for masking the scent of nearby crops, making it harder for pests to find garden vegetables. Specifically, planting thyme with broccoli can reduce infestations by diamondback moths, the most common brassica pest worldwide.
8. Dill
As an umbellifer, dill attracts beneficial insects like hoverflies, lacewings, ladybugs, and parasitic wasps and flies. All of these will help to keep pest populations in check throughout your garden, but they can be particularly helpful with limiting damage from aphids, mites, and caterpillars. Planted with broccoli, dill may also help to physically protect it from pests simply by growing as a tall barrier.
Read More: The 11 Best Companion Plants for Dill
9. Marigolds
Companion planting with marigolds can help repel or confuse pests for a wide variety of vegetables. Planted with broccoli, marigolds can help to:
- Protect against whiteflies
- Reduce damage from aphids, cabbage butterflies, cabbage moths, and flea beetles
- Reduce root-knot nematode populations
- Support parasitic wasps that prey on stink bugs
- Reduce diamondback moth populations
- Disrupt the cabbage root fly's ability to locate brassica plants
10. Nasturtiums
Nasturtiums are another classic companion flower. There's evidence that nasturtiums may also help reduce whitefly populations, as well as attract nematodes and aphids away from other plants. As an added benefit, planting nasturtiums with broccoli can help suppress weeds as the flowers have a low-growing, spreading habit.
To grow nasturtiums as a trap crop, give them time to become established in the soil before planting out broccoli starts. Leaving a couple of inches of bare soil between your nasturtiums and broccoli can also help to isolate pests.
Bad companion plants for broccoli
Planting broccoli with certain crops and herbs can attract pests and stunt crop growth. Here are a few things to avoid planting with broccoli and other cruciferous vegetables:
1. Brassicas
Brassicas like broccoli, kale, cabbage, and cauliflower can't be planted together without increasing the risk of pest infestation. All members of the brassica family share common pests like harlequin bugs, cabbage worms, cabbage loopers, and diamondback moths. Planting them in close proximity creates an ideal environment for these insects. Interplanted brassicas will also compete for nutrients, resulting in a poorer harvest all around.
The one exception to this rule is using another brassica as a trap crop for those pests. This works when the sacrificial trap crop is more attractive to a pest than the plant you're trying to protect, as is the case with radishes and flea beetles.
2. Tomatoes
You can grow tomatoes and broccoli together in a small space, but both plants will suffer slightly. Brassicas like broccoli need a lot of nutrients and water, which tomatoes will also compete for.
There is some evidence that interplanting broccoli with tomatoes could reduce damage from certain pests, but those gains are negated by the plants' overall incompatibility.
Read More: The 11 Best Companion Plants for Tomatoes
3. Peppers
Nightshades like peppers and eggplants aren't good companions for broccoli. They'll compete for root space, nutrients, and water, resulting in poorer harvests all around.
Read More: The 16 Best Companion Plants for Peppers
4. Legumes
Companion planting peas and beans with broccoli can result in weaker broccoli plants. This is because legumes need very rich soil, and they also increase the amount of nitrogen in the soil. Broccoli and other brassicas grown in too much nitrogen will actually be more susceptible to pests, so it's best to avoid planting them with legumes.
5. Strawberries
Strawberries are one of the worst companion plants for broccoli for a few reasons. They're heavy feeders that need a very rich soil, for one. They also prefer an acidic soil, while broccoli likes to grow in a slightly alkaline soil.
6. Mint
Though broccoli can benefit from being near potted mint plants, it's not a good idea to plant mint and broccoli side-by-side. Mint spreads more aggressively than any other common garden herb, allowing it to choke out nearby plants in a wide range of soils and situations. Consider companion planting with mint in a nearby pot, instead, to take advantage of mint's ability to disrupt the cabbage root fly's ability to locate brassica plants.
Read More: The 13 Best Companion Plants for Mint
7. Fennel
As an umbellifer, fennel attracts beneficial insects like hoverflies, ladybugs, and parasitic wasps that prey on common brassica pests. Unfortunately, fennel also produces chemicals in the soil that suppress the growth of nearby plants. Like mint and rosemary, fennel is a useful herb to incorporate into a vegetable garden, but don't plant it too close to your broccoli.
Common broccoli pests
Broccoli suffers from a number of common pests, including:
- Aphids
- Cabbage loopers
- Cabbage worms
- Cabbage webworms
- Cutworms
- Armyworms
- Diamondback moth caterpillars
- Flea beetles
- Thrips
- Whitefly
- Root-knot nematodes
- Harlequin bugs
Cabbage worms here refers to small white and large white cabbage butterfly larvae. Elsewhere, the term sometimes refers to a variety of butterfly and moth larvae, including cabbage webworms, southern cabbage butterflies, cabbage loopers, cabbage moths, and diamondback moths.
Harlequin bugs will prey on all brassicas, but they're partial to mustard, turnip, and Chinese cabbage. If you struggle with harlequin bugs in your garden, consider interplanting one of these other brassicas with your broccoli as a trap crop.
In general, the best companion plants for dealing with broccoli pests are onions, radishes, rosemary, sage, and marigolds.