How to Grow Radish
Raphanus sativus
Radishes are a quick, cool-season crop for full sun and moist, free-draining soil. Direct sow little-and-often from spring and again late summer for autumn harvests. Keep moisture steady to prevent pithy roots; thin promptly for uniform size. Fast maturing—harvest as soon as bulbs reach the size you like. Provide light shade in hot spells to delay bolting. Flea beetle can pit leaves; covers help. For daikon/winter types, allow more space and a longer growing period.
When to Start
Direct sow outdoors as soon as soil reaches 6°C — typically early to mid spring. Hardy enough to tolerate light frosts.
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Growth Stages
Approximate days from start
Care Essentials
- Rarely needed. Quick-growing — ready in 4–6 weeks from sowing.
- The fastest vegetable — perfect for impatient gardeners and children. Sow little and often.
Companion Planting
Lettuce, Garden Peas, Cucumber
Growing Conditions
- Min. soil temperature
- 6°C+
- Germination temperature
- 8–25°C
- Direct sow
- —
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Spacing & Planting
| Plant spacing | 5 cm |
| Row spacing | 20 cm |
| Sow depth | 1 cm |
| Mature height | 20 cm |
| Mature spread | 10 cm |
Thin seedlings to this spacing to allow roots to bulb up. Can be interplanted with slower-growing crops.
Companion Planting
Grows well with
Radishes break through compacted topsoil in days, creating micro-channels that improve water penetration for lettuce's delicate seedling roots. They also serve as row markers for the slower-germinating lettuce, preventing accidental disturbance.
▼Peas fix atmospheric nitrogen through root nodule bacteria, enriching the soil for fast-growing radishes planted alongside. The upright pea stems also provide light wind shelter that keeps radish leaves undamaged.
▼Radishes release sulphur-containing volatile compounds from roots and leaves that confuse and deter cucumber beetles, reducing feeding damage on nearby cucumbers. Plant radishes as a border or interplant every 30 cm along cucumber rows for best effect.
▼Nasturtiums act as a trap crop — their glucosinolate-rich tissues are highly attractive to aphids, which colonise the nasturtium instead of the radishes. Remove heavily infested nasturtium stems periodically to prevent aphid populations from spilling back.
▼Pests & Diseases
Pest Flea Beetle
Identification: Tiny round holes peppered across leaves giving a shot-hole appearance; small, shiny black beetles that jump when disturbed
- Cover rows with fine mesh or fleece immediately after sowing
- Keep soil moist — flea beetles prefer dry conditions
- Sticky traps placed near rows can reduce numbers
- Spray with pyrethrin-based insecticide in the evening when beetles are less active
Pest Slugs and Snails
Identification: Seedlings eaten off at ground level; irregular holes in leaves; slime trails on soil and foliage
- Apply organic slug pellets (ferric phosphate based) around seedlings
- Hand-pick at dusk; use beer traps
- Encourage natural predators such as frogs, hedgehogs, and ground beetles
- Apply ferric phosphate slug pellets around vulnerable seedlings
Pest Cabbage Root Fly
Identification: Seedlings wilt and collapse despite adequate water; small white maggots found around roots when pulled; tunnels in root flesh
- Cover rows with fine mesh or enviromesh to prevent egg-laying
- Use brassica collars around stems at soil level
- Rotate crops to avoid building up populations
- No effective chemical treatments available to home gardeners; prevention with barriers is the main approach
Disease Clubroot Plasmodiophora brassicae
Symptoms: Swollen, distorted roots; stunted growth; leaves wilt in warm weather but may recover overnight; yellowing foliage
Treatment: No cure once soil is infected — remove and destroy affected plants; do not compost
Prevention: Lime acidic soils to raise pH above 7.0; rotate brassica crops on a 4+ year cycle; improve drainage; start plants in modules with clean compost
Disease Downy Mildew Hyaloperonospora parasitica
Symptoms: Yellow patches on upper leaf surfaces with white or grey fuzzy growth on undersides; leaves may curl and die back
Treatment: Remove affected leaves; improve air circulation; avoid overhead watering
Prevention: Space plants adequately; water at the base; ensure good airflow; avoid overcrowding
Growing Conditions
| Min. soil temperature | 6°C |
| Germination temperature | 8–25°C |
| Base growth temperature | 4°C |
| Min. daylength to start | 8.5h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Radish?
- Plant Radish 5cm apart with 20cm between rows.
- What grows well with Radish?
- Radish grows well with lettuce, garden peas, cucumber.
- Is Radish frost hardy?
- Radish is classified as Hardy.
