Radishes repay a little planning around what grows beside them. Radish plants need full sun, soil with a pH of 6.0–7.0, 2–3 inches of space and 25–40 days to reach maturity, so their neighbours need to suit the same bed and the same season. This guide lists the companions for radishes from our crop data, how each one is thought to help, and which close relatives to keep apart.
There are 4 companions listed for radishes here: marigolds, basil, onions, lettuce. Companion planting is traditional garden practice rather than proven science, so benefits below are described in those terms — what gardeners have long said and done. Radishes are in the Brassicaceae family, need moderate water, and are sown directly where it is to grow; it is hardy, so it tolerates cold and can be sown or planted out early in the season. Check any pairing first with the companion-planting finder.
Best companion plants for radishes
| Companion | Why it is grown with radishes |
|---|---|
| Marigolds | Grown as a border or dotted through the bed; roots are traditionally said to discourage some soil pests, and flowers attract beneficial insects. |
| Basil | Traditionally said to improve flavour; its strong scent may confuse pests. Draws pollinators when it flowers. |
| Onions | Take up little space at the bed edge; strong scent is traditionally said to confuse pests that hunt by smell. |
| Lettuce | Grows low and fast, shading the soil and acting as a living mulch while radishes grow taller. |
Basil is the classic partner for radishes, and it earns its place for practical reasons too. It is compact enough to fit into the gaps at the edge of the bed without competing for the space radishes need, and it is harvested all summer. Plant it at the sunny edge where it will not be shaded out, pinch the tips to keep it bushy, and let a few plants flower late in the season to draw in pollinators.
How companion planting works
Companion planting works through four overlapping mechanisms.
Pest confusion. Many pests find their host plant by scent. Strong-smelling companions such as onions, basil and aromatic herbs are traditionally said to mask that scent, so the pest passes by. It is a delaying effect, not a barrier.
Pollinator and beneficial-insect attraction. Several companions here flower — marigolds, basil — drawing pollinators and beneficial insects in. Let a few flower.
Nitrogen fixing. Nitrogen fixing does not apply here — none of the listed companions is a legume.
Ground cover and root layers. Ground cover comes from lettuce, whose low growth shades the soil and holds moisture in. Deep roots beside shallow ones also compete less for water and nutrients.
None of this replaces the basics. Spacing, watering, rotation and weekly inspection matter more than any pairing.
Plants to avoid near radishes
The plants to keep away from radishes are its own relatives. Radishes belong to the Brassicaceae family, and plants in the same family share the same pests and diseases — here, cabbage worms, aphids, flea beetles — so problems pass easily between them and build up in the soil.
| Plant to avoid | Why |
|---|---|
| Broccoli | Same Brassicaceae family; shares pests such as cabbage worms, aphids, flea beetles. |
| Cauliflower | Same Brassicaceae family; shares pests such as cabbage worms, aphids, flea beetles. |
| Cabbage | Same Brassicaceae family; shares pests such as cabbage worms, aphids, flea beetles. |
| Kale | Same Brassicaceae family; shares pests such as cabbage worms, aphids, flea beetles. |
Keep these relatives in a different bed and rotate the Brassicaceae family to fresh ground each year. Others in the same family in our crop data include Turnips, Brussels Sprouts, Collard Greens, Mustard Greens, Arugula, Bok Choy, Kohlrabi, Rutabaga.
Planting layout and spacing
Give radishes their full spacing of 2–3 inches between plants. Crowded radishes mean poor airflow, more disease and smaller harvests, and no companion plant compensates for it. Work out how many plants fit your bed with the plant-spacing calculator or the square-foot garden planner.
Plant companions in the spaces the spacing leaves, not instead of it. Low companions go in the gaps and along the bed edges; taller ones go at the north side so they do not shade the radishes; scented herbs go closest to the crop, dotted through the row.
Radishes are sown directly where it is to grow, so sow where they are to grow and thin to the final spacing once seedlings are up. Germination takes 4–7 days. Radishes need full sun and soil with a pH of 6.0–7.0. Water needs are moderate, so keep the soil consistently moist with deep, regular watering rather than a light daily sprinkle, and mulch thickly to hold moisture in. The watering calculator gives a starting point for your bed size. Expect 25–40 days from sowing to maturity.
Common problems and fixes
The pests most often reported on radishes are cabbage worms, aphids, flea beetles, slugs. Companions may reduce pressure, but they do not prevent them — inspect leaf undersides and new growth weekly and act while numbers are low.
| Problem | What you see | First fix |
|---|---|---|
| Cabbage worms | Velvety green caterpillars chew large holes in leaves. | Pick off eggs and caterpillars; use netting. |
| Aphids | Sap-sucking insects on new growth; leaves curl. | Wash off with water; encourage ladybirds. |
| Flea beetles | Tiny jumping beetles chew small holes in young leaves. | Fine mesh or row cover on young plants. |
| Slugs | Ragged holes in leaves after rain, with silvery trails. | Water in the morning; clear damp debris. |
Cabbage worms
Check leaf undersides weekly for eggs and caterpillars, pick them off, and cover the crop with fine mesh netting.
Aphids
Wash them off with a strong jet of water and leave ladybirds and lacewings alone to eat them.
Flea beetles
Cover young plants with fine mesh or row cover until they are strong.
Slugs
Water in the morning so the surface dries by night, and clear damp debris where slugs hide during the day.
Unsure what you are seeing? Try the pest-identifier helper or the plant-disease checker. Remove badly affected leaves and rotate the Brassicaceae family next year.
Frequently asked questions
What is the best companion plant for radishes?
The most widely recommended companion is marigolds. Grown as a border or dotted through the bed; roots are traditionally said to discourage some soil pests, and flowers attract beneficial insects.
What should not be planted near radishes?
Avoid other members of the Brassicaceae family, including Broccoli, Cauliflower, Cabbage. They share the same pests and diseases as radishes, so problems move easily between them. Rotate the family to a fresh bed each season.
Can I plant radishes with basil?
Yes. Basil is on the companion list for radishes. Traditionally said to improve flavour; its strong scent may confuse pests. Draws pollinators when it flowers.
How far apart should radishes and their companions be planted?
Space radishes plants 2–3 inches apart, and put companions in the gaps, along the edges and at the ends of rows. The plant-spacing calculator works out how many plants fit your bed.
Does companion planting replace pest control?
No. It may reduce pest pressure, but it does not replace inspection, spacing, watering, rotation and good airflow. Check plants weekly and act early.