When to plant radishes?
Salad radishes are sown in spring, early summer and late summer, and from February under cloches in pre-warmed soil, while winter ones go in during July or August. Campania sets no month: growth starts from a monthly mean of 5 °C and is happiest between 15 and 18 °C.
When, by region
| North | Centre | South | |
|---|---|---|---|
| Sowing | Salad types: spring, early summer and late summer. From February, under cloches, in pre-warmed soil. Winter ones, in July or August. Oriental ones, in spring and summer. Germination in 7-10 days. | Umbria's 2025 sheets do not include radish, and no month is written. | Campania sets no month. Sicily's guide has no sowing chapter. |
| Temperature | Salad seed 1 cm deep, plants 2.5-5 cm apart, rows 15 cm apart. Winter ones about 2 cm deep, plants 15-20 cm apart. A pot at least 30 cm wide. Hot, dry weather sends them to flower. | As in the north for the RHS window. Umbria does not write a degree threshold. | Growth from a monthly mean of 5 °C, optimum between 15 and 18 °C. High temperatures and long days make the root spongy and hot, and send it to flower. Cut at 2-3 cm, about 30 days for round ones and 50-60 for long ones. |
Hot, dry weather sends them to flower and the root does not swell. Sow a few seeds every couple of weeks.
Spring, early summer, late summer, February under cloches, July or August, the 7-10 days, 1 cm, 2.5-5 cm, 15 cm, 2 cm, 15-20 cm and a 30 cm pot are from the RHS. The 5 °C monthly mean, 15-18 °C, 2-3 cm, 30 days and 50-60 days are from Campania, which sets no month. Sicily's guide has no sowing chapter. Umbria's 2025 sheets do not name radish. It is a brassica: the plan is in crop rotation. The months are in the February calendar, March, April, May, June, July and August.
A few, and often
The RHS sows them in small batches. Salad types, in spring, early summer and late summer. Hot, dry weather sends them to flower: in summer, choose light shade and soil that does not dry out. To get ahead, from February, in pre-warmed soil under cloches. Seed goes 1 cm (½ in) deep, 2.5-5 cm (1-2 in) apart, rows 15 cm (6 in) apart. They are up in 7-10 days. Winter ones, larger and slower, in July or August, about 2 cm (1 in) deep, plants 15-20 cm (6-8 in) apart. Sown too early, they flower and the root does not swell. Oriental ones, in spring and summer, at the same spacing as the winter types.
Pull them small. Salad ones, in 4 weeks, or 6-8 if the sowing is early, once the root is about 2.5 cm (1 in) across. Left to grow, they turn pithy and hot. Winter ones stay in the ground and are dug as needed, or lifted in November and kept cool. In freezing weather, cover them. Surface sowing, and the row, are in starting seeds indoors only if you start in a pot: normally they go where they will grow.
Campania, degrees and no months
Campania's guide does not write a month. It prefers cool weather and fears long hot spells. Minimum growth is a monthly mean of 5 °C. The optimum sits between 15 and 18 °C. High temperatures and long days make the root spongy and hot, and induce flowering. Cut at 2-3 cm across, about 30 days after sowing for round cultivars and 50-60 for long ones. A delay makes them hotter and spongier. Round types need about 1.5-2 kg of seed per 1,000 m². For long ones, the seed is halved. Succession after rocket, turnip and cabbages is advised against.
Sicily's guide has no sowing chapter. Umbria's 2025 sheets do not name radish. Where the regional month is missing, the RHS seasons and the packet still apply. Rocket, which bolts in the same heat, is in when to plant rocket.
Even water, a pot, the family
Keep the soil moist. Drought stops the root. Uneven water splits it. In spring, with rain, they do better than in summer. How much is in watering.
A pot at least 30 cm (1 ft) wide and deep suits the short-rooted salad types. It dries out fast. See the container garden. They are brassicas: if clubroot is in the garden, they sit with the cabbages. The plan is in crop rotation. Cabbage root fly mainly troubles the winter and oriental types, which stay in the ground longer. Flea beetles make holes in the leaves, usually without stopping the plant. The wider picture is in pests and diseases.
In the app
Every plant in the catalogue has its own sowing calendar, and weather alerts for your area help you judge whether to sow now or hold off.
Frequently asked questions
When do I sow salad radishes?
In spring, early summer and late summer. From February, under cloches, in pre-warmed soil. Seed 1 cm deep, plants 2.5-5 cm apart, rows 15 cm apart. They are up in 7-10 days. Skip heat and drought.
What about winter ones?
In July or August, about 2 cm deep, plants 15-20 cm apart. Earlier, they flower and the root does not swell. They stay in the ground through winter, covered if it freezes, or are lifted in November.
What month does Campania write?
None. Growth from a monthly mean of 5 °C, optimum between 15 and 18 °C. Cut at 2-3 cm, about 30 days for round ones and 50-60 for long ones. Sicily and Umbria set no month.
Why is the root small, or split?
Small: drought, heat or plants too close. Split: uneven water. The RHS keeps the soil moist and, in summer, moves the row into light shade.
Do they sit with the cabbages in the rotation?
Yes. For the RHS, radish is a brassica, with turnip and swede, not a root like carrot. In Campania, succession after rocket, turnip and cabbages is advised against.