Companion Planting Chart: Quick Reference for 20 Crops
Use this chart as a planning reference when laying out your vegetable garden. Each crop lists its best companions (plants that provide measurable or consistently observed benefit), plants to avoid (those that compete, cross-infect, or inhibit), and the primary reason for each recommendation. For background on why these pairings work, see the complete companion planting guide.
How to Use This Chart
Look up your primary crop and plan the bed around the best companions column. The 'avoid' column flags plants that should not share the same bed or need meaningful separation (noted where relevant). Neutral pairs — crops that neither benefit nor harm each other — are not listed; plant them wherever space allows.
Evidence levels vary across pairings. Where a mechanism is well-documented (nematode suppression from French marigolds, Rhizobium inhibition by alliums) it is noted. Traditional pairings with consistent gardener support but limited trials are included without a specific mechanism claim.
Companion Planting Quick Reference Chart
| Crop | Best Companions | Avoid | Notes |
|---|---|---|---|
| Tomatoes | Basil, French marigolds, borage, nasturtiums, parsley, carrots, sweet alyssum | Fennel, potatoes, brassicas, corn | Basil: every 45–60 cm; marigolds: dense border for nematodes |
| Peppers | Basil, French marigolds, geraniums (trap), carrots, spinach (spring), sweet alyssum | Fennel, potatoes, brassicas | Geraniums trap thrips; interplant spinach in spring before peppers need full space |
| Aubergines | Basil, French marigolds, nasturtiums, tarragon | Fennel, potatoes, brassicas | Same companions and avoids as tomatoes and peppers (same family) |
| Cucumbers | Nasturtiums, French marigolds, dill, borage, radishes | Potatoes, fennel, sage | Radishes at perimeter reported to deter cucumber beetle; dill attracts beneficial wasps |
| Courgettes / Squash | Nasturtiums, corn (Three Sisters), beans, borage, French marigolds | Fennel, potatoes, other sprawling large plants | Squash is the ground-cover element in Three Sisters; borage attracts bumblebees for large flowers |
| Cabbage | Nasturtiums (trap), dill, sweet alyssum, thyme, celery, spring onions | Tomatoes, strawberries, fennel, climbing beans | Nasturtiums must be established 1–2 weeks before brassicas; thyme may deter cabbage white butterfly |
| Broccoli / Kale | Nasturtiums, dill, marigolds, sweet alyssum, thyme | Tomatoes, fennel, strawberries | Same companion principles as cabbage; dill flowers support parasitoid wasps |
| Beans (climbing) | Carrots, squash, corn, nasturtiums, sweet alyssum | Garlic, onions, leeks, chives, fennel, brassicas | Alliums inhibit Rhizobium nitrogen-fixing bacteria in bean roots — experimentally documented |
| Peas | Carrots, turnips, radishes, lettuce, sweet alyssum | Garlic, onions, leeks, fennel | Same Rhizobium inhibition by alliums as beans; plant peas near tall crops only if peas go in first |
| Carrots | Spring onions, leeks, chives, rosemary, lettuce, tomatoes | Fennel (allelopathic — strong evidence), dill, parsnips | Alternating rows of carrots and spring onions for scent confusion of carrot fly; keep fennel well away |
| Onions / Garlic | Carrots, brassicas, roses, tomatoes, chamomile | Beans, peas, asparagus, sage | Garlic at rose base deters aphids and may reduce black spot fungal infection |
| Leeks | Carrots, celery, parsnips, chamomile | Beans, peas, fennel | Leeks and carrots traditionally paired for mutual pest deterrence |
| Potatoes | French marigolds, horseradish (corners), nasturtiums, beans, coriander | Tomatoes, cucumbers, sunflowers, fennel, any Solanaceae | Sunflowers are allelopathic to potatoes (documented); tomatoes share late blight |
| Lettuce | Carrots, chives, radishes, spring onions, tomatoes (shade in summer) | French marigolds (close to seedlings), fennel, celery (some reports) | Plant lettuce between tomato transplants in spring — harvested before tomatoes shade it; marigolds inhibit lettuce germination at close range |
| Spinach | Strawberries, tomatoes (spring), beans, peas, celery | Fennel | Spring spinach in gaps between tomato transplants — harvested by June before tomatoes need space |
| Basil | Tomatoes, peppers, aubergines, asparagus, root vegetables, marigolds | Sage (close proximity), fennel, mint (containers) | Sage may inhibit basil growth at close range; mint outcompetes in containers but is manageable in open ground |
| Parsley | Tomatoes, asparagus, roses, chives | Mint (competition), fennel | Second-year parsley in flower supports parasitoid wasps; allow some plants to bolt for this purpose |
| Roses | Garlic, chives, lavender, catmint/Nepeta, French marigolds, parsley, geraniums | Fennel, brassicas, boxwood, mint, large trees | Garlic cloves planted at rose base in autumn deter aphids; lavender shares alkaline well-drained soil preference |
| Strawberries | Borage, lettuce, garlic, thyme, marigolds | Brassicas, fennel, potatoes (verticillium wilt) | Borage is the classic strawberry companion; traditionally reported to improve vigour and repel pests |
| Asparagus | Basil, parsley, tomatoes | Garlic, onions, potatoes, fennel | Basil may deter asparagus beetle; asparagus is perennial — plan companions that work around its permanent placement |
Beneficial Flowers: Universal Companions
These flowers can be added to any vegetable bed regardless of what's growing there:
| Flower | Benefit | Spacing | Notes |
|---|---|---|---|
| French marigolds | Nematode suppression (thiophene root exudates) | Every 20–30 cm in a dense border | Must be planted at high density to be effective; keep away from lettuce seedlings |
| Sweet alyssum | Parasitoid wasp and hoverfly habitat | Sow in gaps at bed edges | Self-seeds readily; low growing (won't shade crops) |
| Nasturtiums | Aphid trap crop; attracts pollinators | Perimeter; 1–2 weeks before main crop | Monitor regularly and treat aphids on nasturtiums before they spread |
| Borage | Bumblebee attraction; buzz pollination for fruiting crops | 1–2 plants per 4 m² of bed | Self-seeds prolifically; edible flowers |
| Phacelia | Exceptional early-season bee and hoverfly attraction | Direct sow in early spring in gaps | Flowers before most crops; handle with gloves if you have sensitive skin (contact dermatitis risk) |
| Calendula | Aphid and whitefly trap crop; beneficial insect support | Between rows; 30 cm intervals | Harvest flowers regularly to prolong blooming; edible petals |
Plants to Exclude from the Vegetable Garden
| Plant | Problem | Safe Distance |
|---|---|---|
| Fennel | Broadly allelopathic; inhibits growth of almost all neighbouring plants | 1.5 m minimum from all vegetables |
| Black walnut | Produces juglone toxin lethal to tomatoes, peppers, and other plants; persists in soil 2–5 years after tree removal | 15 m from sensitive plants |
| Mint (uncontrolled) | Invasive root spread; outcompetes other plants in open ground | Contain in buried pots; never plant free in a vegetable bed |