When to Plant Radishes: The Best Time for a Crisp, Crunchy Harvest
Introduction
Radishes are one of the easiest and fastest vegetables to grow, making them perfect for beginner gardeners and quick-growing success stories. But as with all veg, timing is everything. Knowing when to plant radishes ensures a bountiful crop with crisp texture, bright colour, and a satisfying peppery bite.
In this article, we’ll walk you through the best time to plant radishes in the UK, including spring, summer, and autumn sowings. You’ll learn about suitable varieties for each season, how to avoid common mistakes like bolting, and how to get continuous harvests through succession planting.
Quick Answer: When Should You Plant Radishes?
In the UK, the best times to sow radishes are:
- Spring radishes: March to June
- Autumn/winter radishes: August to mid-September
- Indoor/mild climates: Possible from February (under cover)
Radishes prefer cooler weather, so avoid sowing during midsummer heat to prevent bolting and bitter roots.
Spring Radish Planting Calendar (UK)
| Month | Can I Sow? | Notes |
|---|---|---|
| February | ✔ Under cover only | Use a greenhouse or polytunnel |
| March | ✔ Outdoors | Start main sowing in open ground |
| April | ✔ Outdoors | Ideal time for fast spring crops |
| May | ✔ Outdoors | Keep soil moist in warmer spells |
| June | ✔ Early only | Late sowings may bolt in heat |
| July | ✖ Avoid | Too hot—poor flavour, high risk of bolting |
| August | ✔ Late crop sowing | Best time for winter radish types |
| September | ✔ Early month | Use fleece to extend season |
| October–Jan | ✖ Too cold outdoors | Sow only under glass if mild |
Radish Varieties and Their Ideal Planting Times
Different types of radishes have different growing seasons:
| Radish Type | Best Planting Months | Harvest Time | Notes |
|---|---|---|---|
| Cherry Belle | March–June | 3–4 weeks after sowing | Classic red globe radish |
| French Breakfast | March–June | 25–30 days | Elongated red with white tip |
| Daikon (Mooli) | August–September | 50–70 days | Great for stir-fries and stews |
| Watermelon Radish | August–September | 60–75 days | Colourful interiors, slow grower |
| Black Spanish | August | 55–80 days | Hardy winter radish |
| Sparkler | March–May | 25 days | Red/white globe, quick crop |
Spring radishes grow fast and are harvested young. Winter radishes are larger and need more time but store well and are ideal for autumn meals.
Why Planting Time Matters
Planting radishes at the right time affects:
- Flavour – Cool-season radishes are crisp and mildly peppery. Summer-sown ones can be bitter.
- Texture – Proper timing prevents woody, hollow, or pithy roots.
- Growth speed – Spring varieties can be ready in 3–4 weeks if planted in cool weather.
- Bolting – High temperatures cause premature flowering and ruin the crop.
- Pest resistance – Flea beetles and slugs are more active in summer.
How to Prepare for Planting
1. Choose a sunny or partially shaded spot
Radishes like full sun but can tolerate partial shade, especially in warmer months.
2. Improve the soil
Use loose, well-draining soil enriched with compost. Avoid recently manured beds, which can cause excessive leaf growth and poor roots.
3. Avoid overcrowding
Sow thinly or thin seedlings early to allow space for roots to swell.
How to Plant Radish Seeds
✅ Sowing Outdoors:
- Rake soil to a fine tilth
- Create shallow drills ~1cm deep
- Sow seeds 1–2cm apart, cover lightly with soil
- Water gently and label the row
- Thin seedlings to 2–3cm apart once they emerge
✅ Under Cover or in Containers:
- Use deep trays or pots with good drainage
- Sow in compost mixed with sand for light texture
- Keep in unheated greenhouse, cold frame, or sunny windowsill
- Great for early crops in Feb/March
Tips for Succession Planting
To get continuous radish harvests through the season:
- Sow little and often – every 7–10 days
- Choose fast-growing varieties like ‘Cherry Belle’
- Alternate beds every few weeks to prevent pest build-up
This method gives you fresh radishes all spring and autumn without a glut.
Avoiding Common Problems with Timing
| Problem | Cause | Fix |
|---|---|---|
| Bolting | Hot weather or drought stress | Sow earlier or later, provide shade |
| Tiny roots | Planted too late or overcrowded | Thin seedlings, sow in cooler months |
| Hollow centres | Over-maturity or summer heat | Harvest promptly, sow in spring/autumn |
| Tough skin | Left in ground too long | Check for harvest readiness after 3–4 weeks |
| No roots, only leaves | Over-fertile soil or poor timing | Balance nutrients, sow in right season |
When to Harvest Radishes (Based on Sowing Date)
- Fast-growing spring types: 21–30 days after sowing
- Check for visible shoulders at soil surface
- Roots should feel firm and round
- Harvest quickly—don’t leave them to get oversized or spongy
Tip: In cooler weather, radishes may take a week longer. Be patient but check regularly!
Can You Plant Radishes Indoors or in Winter?
Yes—but with care:
- Early spring (Feb–March): sow under glass or indoors
- Use cold frames, mini greenhouses, or south-facing windows
- Radishes don’t need high heat but do require light and moisture
- Avoid waterlogging in winter containers
Conclusion
Knowing when to plant radishes is the secret to perfect roots: crunchy, mild, and ready in weeks. Stick to spring and late summer for the best results, and avoid planting during high summer heat.
By choosing the right varieties for each season and practising regular sowing, you’ll enjoy a steady supply of radishes from March to October—whether in your garden, on the allotment, or in a container by the door.
Fast-growing, easy to manage, and incredibly rewarding—radishes are the perfect crop to master your seasonal sowing game.
Top 10 Questions and Answers About When to Plant Radishes
1. What’s the best time to plant radishes in the UK?
March to June for spring types, and August to September for autumn/winter types.
2. Can I plant radishes in February?
Yes—under cover or indoors using a greenhouse, cold frame, or windowsill.
3. What happens if I plant radishes too late?
They may bolt, grow poorly, or develop hollow or bitter roots.
4. Can you plant radishes in July?
It’s not ideal—summer heat leads to bolting and poor flavour.
5. How long do radishes take to grow?
Most spring types are ready in 3–4 weeks. Winter types take 6–10 weeks.
6. How often should I sow radishes?
Every 7–10 days for a continuous crop during the growing season.
7. Do radishes need full sun?
Yes, but they tolerate partial shade, especially in summer.
8. Can I grow radishes in pots?
Absolutely—use a 6-inch deep container with free-draining compost.
9. Do I need to thin radish seedlings?
Yes—thin to 2–3cm apart once the first true leaves appear.
10. When is the latest I can plant radishes?
Mid-September is the latest for winter types under protection.