Radish
French Breakfast Radish, Cherry Belle, Daikon, Watermelon Radish
Fastest-maturing vegetable — excellent for impatient gardeners and interplanting. Sow directly every 2–3 weeks for continuous harvest. Bolts quickly in heat (spring window is short). Harvest as soon as sizing up; over-mature radishes become pithy and hot. Useful as 'trap crop' for flea beetles to protect brassicas.
- Germination
- 3–7 days
- Soil temperature
- 7–29 °C
- Harvest after sowing
- 22–35 days
- Spacing
- 5–8 cm
When to plant radish
Sow outdoors 2–4 weeks before your last spring frost.
Dashed line: typical last spring frost in zone 7 (Apr 5). Zone dates are averages; most of the UK is zone 8–9, central Europe 6–7 and the Baltics and Scandinavia 4–6. In the app, Tomatograph uses your garden's own frost dates.
How to grow radish
- 1
Sow
Sow 1 cm deep 2–4 weeks before the last frost. Radishes appear in 3–7 days, so they are useful for marking rows of slower crops.
- 2
Keep sowing
Sow a short row every 10 days until early summer heat sets in, then start again in late summer.
- 3
Water
Keep the soil evenly moist; dry soil makes radishes hot and woody.
- 4
Harvest
Pull as soon as roots size up, 22–35 days after sowing. Left too long they turn pithy and sharp.
Growing conditions
Light
Full sun
Water
Medium water
Temperature
4–22 °C
Frost tolerance
Frost-hardy — tolerates frost
Days to maturity
22–35 days
Plant spacing
5 cm
Ideal soil pH
5–5.5
How Tomatograph watches your radish
Tomatograph checks your local forecast every morning and only speaks up when one of these applies to your garden.
- First frost within 14 daysReminder to mulch the roots before winter.
- 3 days at 35 °C or aboveHeat-wave alert while plants are flowering or fruiting: shade and water early.
- Humidity above 80% for 48 hoursCheck for clubroot, which thrives in those conditions.
- Within a week of maturityHarvest-window reminder based on when you planted.
Radish questions
- When should I plant radish?
- Sow outdoors 2–4 weeks before your last spring frost.
- How long do radish seeds take to germinate?
- Usually 3–7 days at a soil temperature of 7–29 °C.
- How long until I can harvest radish?
- About 22–35 days after sowing, depending on variety and weather.
- How far apart should I plant radish?
- Allow 5–8 cm between plants.
- What grows well with radish?
- Good neighbours include carrot, cucumber, lettuce, pea.
Growing guide written by Tomatograph. Planting figures from openplantdb (CC0 1.0). Zone frost dates are averages from openplantdb (CC0 1.0).