What Not to Plant Near Kale? 10 Plants to Avoid, Why, and Better Alternatives

Introduction: Why where you plant kale matters

Three summers ago I tucked kale into a crowded bed next to tomato cages and strawberries, thinking more plants meant more food. Within weeks the kale was leggy, chewed by cabbage worms, and offered tiny heads instead of the lush greens I expected. That taught me to ask what not to plant near kale?

Kale is thirsty for sun and nutrients, and it shares pests with other brassicas. Bad neighbors reduce yield by shading or stealing nutrients, and they make pest outbreaks worse by concentrating cabbage moths, cabbage maggots, and aphids.

This guide gives practical, beginner friendly advice: 10 plants to avoid, why each causes trouble, and simple alternatives you can plant instead to boost harvests and cut pests today.

Quick rule of thumb for kale neighbors

Want a fast rule for what not to plant near kale? Avoid three things: heavy feeders, plants that share pests, and allelopathic neighbors. Heavy feeders such as tomatoes, corn, potatoes, and squash will hog nitrogen and stunt leafy brassicas. Plants that attract the same pests, for example other brassicas, cabbage, and mustard, invite cabbage worms and flea beetles. Trees and large plants that release growth inhibitors, like black walnut and sometimes sunflowers, can suppress kale. A simple memory trick, think three A’s: Avoid competition, Avoid shared pests, Avoid allelopathy. When unsure, swap in low competition companions such as onions, beets, herbs, or nasturtiums, and rotate crops each season.

Why kale has compatibility issues with other plants

When people ask what not to plant near kale, the answer begins with biology. Kale is a brassica that needs a lot of nitrogen to build big, leafy heads, so other heavy feeders will compete and reduce yields. Its broad, upright leaves create a dense canopy that shades low-growing crops, so carrots, beets and small herbs often underperform when planted too close. Kale also shares pests and pathogens with other brassicas, including cabbage loopers, flea beetles, aphids, clubroot, black rot and downy mildew; putting susceptible plants together makes infestations spread fast. Clubroot prefers acidic, compacted soil, so repeated brassica plantings without liming and deep compost increases risk. Practical rules, give kale 18 to 24 inches between plants, rotate brassica beds every three years, and avoid clustering multiple brassicas in the same bed to limit nutrient competition and disease transmission.

10 plants not to plant near kale and why

If you searched what not to plant near kale? here are ten plants that routinely cause problems, why they do it, and a one line example you can act on.

1. Broccoli, reason: same Brassicaceae family, shares pests like cabbage worms and encourages soil disease buildup. Example: avoid broccoli next to kale, rotate them to different beds and plant dill between seasons.

2. Cabbage, reason: heavy nutrient competition and common diseases such as clubroot will jump between them. Example: do not pair cabbage with kale, space them weeks apart and use compost to restore nutrients.

3. Cauliflower, reason: another heavy feeder that invites the same pests and depletes soil nitrogen and magnesium. Example: keep cauliflower out of the immediate kale patch, plant legumes elsewhere to rebuild soil nitrogen afterward.

4. Brussels sprouts, reason: long growing season gives pests a continuous host, increasing pressure on nearby kale. Example: avoid planting Brussels sprouts beside kale, stagger plantings so pests cannot overwinter on both.

5. Fennel, reason: strong allelopathic compounds inhibit brassica growth and weaken surrounding plants. Example: never plant fennel close to kale, relocate fennel to a separate herb bed.

6. Black walnut, reason: tree roots exude juglone, a toxin that stunts or kills many garden vegetables. Example: keep kale out of walnut root zones, use raised beds with fresh soil instead.

7. Strawberries, reason: share fungal diseases and attract slugs that love young kale seedlings. Example: do not club strawberries and kale together, plant strawberries at the far end of the garden or in containers.

8. Mint, reason: invasive runners crowd roots and steal moisture, making kale suffer. Example: never plant mint directly next to kale, confine mint to pots or a separate bed.

9. Tomatoes, reason: can harbor aphids and whiteflies that migrate to kale, and they prefer different soil care. Example: avoid mixing tomatoes and kale in close rows, separate them by at least several feet and use insect monitoring.

10. Sunflowers, reason: tall, competitive roots and mild allelopathy create shade and chemical stress for low growing kale. Example: do not plant sunflowers on the windward side of kale, position them well away or on the opposite boundary.

Common pests and diseases that get worse with bad neighbors

Gardeners often ask, what not to plant near kale? The key pests and diseases to watch are mostly those that use brassicas as hosts, and nearby plants can act as reservoirs.

Common pests, with signs

• Flea beetles, tiny shot holes across young leaves and stunted seedlings.
• Cabbageworms and loopers, large ragged holes and frass on lower leaves.
• Aphids, clusters on new growth, sticky honeydew and curled leaves.

Common diseases, with signs

• Clubroot, swollen, knobbly roots and overall wilting in cool wet soil.
• Downy mildew, pale yellow patches on upper leaf surfaces and gray fuzz below.
• Black rot, V shaped yellow lesions at leaf edges with black veins.

Why neighbors matter: planting other brassicas, volunteer mustards, or dense leafy greens nearby gives insects breeding sites and promotes splash dispersal of fungal spores. Practical checks, remove volunteers, increase spacing, and inspect undersides of leaves weekly.

Best companion plants for kale, practical examples

Think of companions as insurance, they protect kale from pests, shade the soil, or feed the soil. Here are reliable choices and why they work.

• Nasturtiums, trap pests such as aphids and flea beetles, they draw bugs away from kale and trail nicely from containers.
• Marigolds, deter root nematodes and many soil pests, plant them around borders or in beds.
• Borage, attracts pollinators and parasitic wasps, it also improves brassica vigor and can deter cabbage moths.
• Garlic and chives, repel aphids and caterpillars with sulfur compounds, tuck them between plants.
• Beans and peas, nitrogen fixing plants that boost soil fertility near heavy feeders like kale.
• Dill and cilantro, attract beneficial predators such as ladybugs and hoverflies, plant them at the edge of the patch.
• Spinach or lettuce, quick harvests that act as living mulch, keeping moisture up and weeds down around young kale.

Two sample combos
Small container, 1 to 2 kale plants: center kale, edge nasturtiums trailing, a clump of chives for pest deterrence, one borage for pollinators.
4×4 raised bed, 5 to 8 kale plants: stagger kale rows, north edge planted with pole beans, marigolds in corners, dill/cilantro at the perimeter, spinach between kale for ground cover.

How to plan your garden layout and rotation to avoid trouble

1. Sketch your beds, label plant families, then block out where kale will go this year. Keep kale plots at least 12 to 24 inches between plants, and 18 to 36 inches between rows for airflow and easier pest scouting.

2. Rotate by family, not individual crop. If you plant kale one year, avoid all brassicas in that bed for two to three years; pests and diseases like cabbage worms and clubroot linger in soil.

3. Use a simple three year rotation: year one brassicas, year two legumes or root vegetables, year three solanaceae or cucurbits. This breaks pest cycles and balances soil nutrients.

4. Stagger planting times, for example early spring kale and a late summer succession crop, to reduce continuous host availability for pests.

5. Clean up crop debris each fall, and plant a cover crop such as clover to rebuild organic matter and suppress pathogens.

Following these steps answers what not to plant near kale? and prevents repeat problems.

Quick companion swap cheat sheet

Quick answer to "what not to plant near kale?" Swap these risky neighbors for better companions, so you can change your seed list in one pass.

Tomatoes, borage attracts pollinators and helps brassicas.
Potatoes, onions or garlic, alliums deter soil pests.
Strawberries, chives reduce fungal disease pressure.
Cucumbers, nasturtiums, trap pests away from kale.
Pumpkins and squash, Swiss chard, less shading.
Melons, thyme as low pest deterrent.
Peppers, marigolds for general pest control.
Pole beans, choose bush beans to avoid shade.
Grapes and vines, swap to herbs.
Fennel, never, use dill or cilantro instead.

Conclusion and final actionable checklist

If you searched "what not to plant near kale?" the short answer is, avoid plants that bring the same pests or steal nutrients. Other brassicas, heavy feeders, and crowding cause most problems.

Checklist to use when planting kale

1. Do not plant other brassicas nearby, rotate families each season.
2. Avoid crowding, give standard kale 12 to 24 inches spacing.
3. Skip plants that attract the same pests, for example certain nightshade crops.
4. Plant alliums and aromatic herbs as better alternatives.

Next step, map your bed, swap risky neighbors now, then plant.