Kohlrabi Companion Planting (Best and Worst Neighbors)

Companion planting is the practice of growing certain plants near each other for mutual benefit — pest control, improved pollination, better nutrient use, or simply making efficient use of garden space. For kohlrabi specifically, companion planting can make the difference between a productive harvest and a frustrating season of pest damage and stunted growth.

Kohlrabi is a brassica (the same family as cabbage, broccoli, and Brussels sprouts), and like all brassicas, it has specific companions that help it thrive and specific neighbors that cause problems. Here’s the complete guide to what to plant near your kohlrabi — and what to keep far away.

Best Companion Plants for Kohlrabi

Aromatic Herbs

Dill. One of the best companions for kohlrabi. Dill attracts beneficial insects — particularly parasitic wasps and lacewings — that prey on cabbage worms, aphids, and other brassica pests. Plant dill in clusters near your kohlrabi rows, not interspersed among the kohlrabi plants (dill can get tall and shade the lower-growing kohlrabi).

Chamomile. Improves the flavor and growth of brassicas (according to companion planting tradition) and attracts hoverflies, whose larvae eat aphids. Plant chamomile at the ends of kohlrabi rows or along borders. It stays relatively low and doesn’t compete for space.

Thyme. The strong scent of thyme is thought to confuse and repel cabbage moths — the white butterflies whose caterpillars (cabbage worms) are the number one pest for all brassicas, kohlrabi included. Low-growing creeping thyme makes an excellent living mulch between kohlrabi plants, suppressing weeds while providing pest protection.

Mint. Another strong-scented herb that deters aphids and flea beetles. However, mint is aggressively invasive — never plant it directly in the garden bed. Grow it in containers placed near your kohlrabi, or use cut mint stems as mulch around the base of kohlrabi plants. The scent still works without the invasive root system taking over your garden.

Rosemary and Sage. Both produce strong aromatic oils that repel cabbage moths, carrot flies, and various other garden pests. They’re perennial in most climates, so plant them as permanent borders near your kohlrabi rotation area.

Vegetables

Beets. An excellent companion for kohlrabi. They occupy different soil depths — kohlrabi forms its bulb above ground while beet roots grow below the surface — so they don’t compete. Beets also help loosen soil as their roots push down, which benefits kohlrabi’s relatively shallow root system. The two can be interplanted in the same bed with tight spacing.

Lettuce and other salad greens. Fast-growing lettuce fills in the space between kohlrabi plants while both are young. By the time kohlrabi needs more room, the lettuce is typically ready to harvest. This is called succession interplanting and it maximizes garden productivity. Lettuce also acts as a living mulch, keeping the soil cool and moist — conditions kohlrabi prefers. If you’re growing kohlrabi in containers, tuck a few lettuce starts around the edges.

Onions, garlic, and leeks (alliums). The pungent smell of alliums masks the scent of brassicas from pest insects that locate their host plants by smell. Cabbage moths, aphids, and flea beetles all use chemical cues to find brassica crops — a strong-smelling allium neighbor disrupts this process. Interplant onion sets between kohlrabi plants, or border your kohlrabi rows with garlic.

Celery. Repels cabbage white butterflies with its strong scent. Celery and kohlrabi have similar water requirements (both like consistent moisture), so they’re easy to manage on the same irrigation schedule.

Bush beans. Legumes fix atmospheric nitrogen into the soil through their root nodules, making it available for neighboring plants. Kohlrabi is a moderate to heavy nitrogen feeder, so having beans nearby provides a natural fertilizer source. Plant bush beans (not pole beans, which would shade the kohlrabi) in adjacent rows.

Cucumbers. A surprisingly good pairing. Cucumbers sprawl along the ground and act as living mulch around upright kohlrabi plants, keeping soil moist and cool. They don’t compete for the same nutrients, and there’s no known pest or disease overlap between the two crops.

Flowers

Marigolds. The classic companion plant, and for good reason. French marigolds (Tagetes patula) release compounds from their roots that suppress root-knot nematodes in the soil. They also repel whiteflies and attract hoverflies that eat aphids. Plant marigolds as a border around brassica beds — they provide pest protection and look good doing it.

Nasturtiums. Function as a trap crop for aphids. Aphids love nasturtiums even more than they love brassicas, so the nasturtiums draw the aphids away from your kohlrabi. Plant them at the perimeter of the garden bed, not right next to the kohlrabi. Check the nasturtiums regularly and remove heavily infested ones to keep the aphid population in check.

Borage. Attracts pollinators and predatory insects. While kohlrabi doesn’t need pollination for its bulb (you’re harvesting the stem, not a fruit), the beneficial insects that borage attracts — particularly parasitic wasps — help control caterpillar pests across the garden.

Plants to Keep Away from Kohlrabi

Not every plant is a good neighbor. Some actively hinder kohlrabi growth through competition, shared pests, or chemical interference.

Other Brassicas

Cabbage, broccoli, Brussels sprouts, cauliflower, kale. This might seem counterintuitive — shouldn’t related plants grow well together? In practice, planting multiple brassicas together concentrates the pest and disease pressure. Cabbage moths, flea beetles, aphids, and clubroot fungus all target the brassica family. A bed full of brassicas is a buffet for these pests, while spreading brassicas throughout the garden forces pests to search harder for their hosts.

If you’re growing multiple brassicas (most vegetable gardeners do), spread them across different areas of the garden and interplant with companions from the lists above. Don’t devote an entire bed to the brassica family.

Strawberries

Strawberries and kohlrabi are commonly listed as poor companions. Both are susceptible to some of the same soil-borne diseases, and strawberries can harbor slugs that will move to kohlrabi. The low-growing, dense strawberry plants also create humid conditions near the soil surface that promote fungal issues in nearby kohlrabi.

Tomatoes and Peppers (Nightshades)

Tomatoes and kohlrabi are frequently cited as incompatible companions. Tomatoes are heavy feeders that compete aggressively for soil nutrients, potentially stunting kohlrabi growth. Some companion planting traditions also hold that brassicas and nightshades negatively affect each other’s growth through root exudates, though the scientific evidence for this specific claim is limited.

The practical issue is clearer: tomatoes grow tall and cast shade, and kohlrabi needs full sun to develop properly. Kohlrabi that doesn’t get enough light produces leggy tops and undersized, woody bulbs.

Pole Beans and Runner Beans

While bush beans are beneficial companions, tall climbing beans are not. They shade kohlrabi (which needs full sun), and some gardeners report that pole beans and brassicas both grow poorly when planted together. The height difference and resulting shade is the primary concern.

Fennel

Fennel is the garden’s worst neighbor for almost everything, and kohlrabi is no exception. Fennel produces root exudates that inhibit the growth of most nearby plants. It also attracts some of the same pests that target brassicas. Plant fennel far from your vegetable garden or in its own isolated bed.

Grapes

If you have grapevines, keep kohlrabi well away from them. Brassicas and grapes are traditionally considered antagonistic, and kohlrabi planted near grapevines may produce an off flavor in the grapes.

Companion Planting Layout Ideas

Theory is useful, but here’s how to actually arrange these plants in the garden.

Small Raised Bed (4x4 feet)

Plant 4-6 kohlrabi in the center of the bed with tight spacing (6-inch centers). Ring the perimeter with onion sets (every 4 inches). Tuck lettuce starts in the gaps between kohlrabi plants. Plant one marigold in each corner. Put a container of mint at one end of the bed.

This gives you pest protection (onions, mint, marigolds), efficient space use (lettuce as living mulch), and a productive kohlrabi harvest from a small footprint.

Garden Row Layout

If you grow kohlrabi in traditional rows, use this arrangement:

• Row 1: Garlic or onions
• Row 2: Kohlrabi
• Row 3: Bush beans
• Row 4: Kohlrabi
• Row 5: Dill and chamomile
• Border: Marigolds and nasturtiums

This alternates kohlrabi with beneficial companions, never placing two kohlrabi rows adjacent to each other. The allium row provides scent masking, the bean row provides nitrogen, and the herb row provides predatory insect habitat.

Container Companion Planting

Growing kohlrabi in containers doesn’t exclude companion planting. Use a large container (at least 18 inches wide) and plant 2-3 kohlrabi with thyme or chamomile around the edges. Place a separate pot of mint or basil right next to the kohlrabi container. Put a small marigold in a neighboring pot.

The proximity still provides many of the pest-deterrent benefits, even if the plants aren’t sharing soil.

How Companion Planting Fits with Crop Rotation

Companion planting and crop rotation work together. When you grow kohlrabi, you should avoid planting it — or any brassica — in the same spot two years in a row. Crop rotation breaks pest and disease cycles that build up in the soil.

A common rotation for the kohlrabi bed:

• Year 1: Kohlrabi with companions (onions, lettuce, beans, herbs)
• Year 2: Legumes (which fix nitrogen depleted by the kohlrabi)
• Year 3: Root vegetables (carrots, beets, parsnips)
• Year 4: Nightshades (tomatoes, peppers — fine after a 2-year gap from brassicas)
• Year 5: Back to kohlrabi

This four-year rotation prevents clubroot buildup, replenishes soil nutrients naturally, and keeps pest populations from establishing.

Does Companion Planting Actually Work?

Some companion planting advice is backed by solid research. Marigolds suppressing nematodes is well documented. Aromatic herbs reducing pest damage to brassicas has been demonstrated in multiple studies. Trap cropping with nasturtiums has measurable effects on aphid distribution.

Other companion planting claims are traditional knowledge — passed down through generations of gardeners — without rigorous scientific testing. The “bad neighbors” list in particular relies more on observation and tradition than controlled experiments.

The practical approach: use the well-supported companions (herbs for pest control, legumes for nitrogen, flowers for beneficial insects) and experiment with the traditional pairings. Even if some of the folklore is imprecise, the worst outcome of most companion planting is simply that it doesn’t help — it rarely causes active harm. And many gardeners, including commercial growers, find that thoughtful companion planting consistently produces better results than monoculture rows.

What’s not debatable is that diversity in the garden — mixing different plant families, heights, and growth habits — creates a more resilient ecosystem than rows and rows of the same crop. Companion planting with kohlrabi isn’t just about the kohlrabi. It’s about building a garden where everything grows better because of what’s around it.