How to Grow Radishes
Radishes aren’t my all-time favorite vegetable, and I don’t grow as many as I do other crops. But because they’re so easy to grow, they’re one of the first crops I recommend to new gardeners and kids. The seeds sprout quickly, the plants grow fast, and you get a harvest before you’ve had time to lose interest.
Although radishes are usually easy to grow, things don’t always go as planned. Here’s what I’ve learned about when and how to plant radishes, how to care for them, and what makes the difference between crisp, flavorful roots and disappointing ones.
Key Takeaways: How to Grow Radishes
- Radishes are a cool-season crop. In the low desert, sow from mid-September through March. I plant most of mine in October.
- Sow seeds ½ inch deep and thin to 3 inches apart, or 16 per square foot.
- The trick is sun, steady water, and spacing. Most radish problems come back to one of those three.
- Round radishes are usually ready in about 3 to 4 weeks. Harvest when they’re about the size of a quarter.
- Radishes left in the ground too long turn woody, hot, or split.
When I Plant Radishes
Radishes grow best in cool weather, below about 65ºF. In the low desert, you can sow them from mid-September through March. I plant most of mine in October. Then I keep tucking a few seeds into empty spots later in the season. My list of what to plant in October in the low desert has the other crops that go in then.
In colder climates, sow radishes about 4 weeks before your last spring frost, or up to 4 weeks before your first fall frost.
How to Plant Radishes
Sow radish seeds directly in the garden, about ½ inch deep. They sprout quickly, often within a few days, which is part of why kids love them. For more cool-season crops to grow from seed, read this guide.
Radishes need room to form a round root. Thin seedlings to about 3 inches apart once they’re a week or two old. In a square foot garden, that’s 16 radishes per square. Here’s my guide to plant spacing in square foot gardens.
Give them loose, well-draining soil at least 6 inches deep. Skip extra nitrogen fertilizer. Too much nitrogen gives you big leaves and small roots.
Where I Plant Radishes
Radishes grow quickly, so I often interplant them with slower crops like carrots, beets, or parsnips. The radishes are ready and out of the way before the others need the room. You can also plant seeds in empty spots as they open up throughout the growing season. Learn more in my posts on how to grow carrots, beets, and parsnips.
They’re also often grown as a trap crop and can help attract pests away from more vulnerable crops. They draw aphids and flea beetles away from peppers, squash, and cabbage and make the perfect companion plants for cucumbers.
The Trick to Growing Radishes: Sun, Water, and Spacing
I’ve had just about every radish problem there is: radishes that never bulbed, split, turned hot or woody, or bolted. Looking back, almost every one came down to sun, water, or spacing.
- Sun. Radishes need at least 6 hours of direct sun. In too much shade, you get leaves and no root.
- Water. Keep the soil evenly moist. Dry spells make radishes hot and pithy. Dry soil followed by a heavy watering makes them split.
- Spacing. Crowded radishes don’t bulb. Thinning often feels wasteful, but it’s what gives you good-sized roots.
Radish Varieties I’ve Grown
I don’t grow every variety every year, but I’ve grown all of these. (Click on the names for seed sources)
| Variety | What it’s like | My take |
|---|---|---|
| Watermelon Radish | Green outside, bright pink inside | My favorite. The color is so fun and unexpected when you slice one open. |
| Cherry Belle | The classic small, round red radish | Fast and easy, a good first radish. |
| White Daikon | Long white roots that can reach 18 inches | Needs deep, loose soil and more time. |
| Round Black Spanish | Black skin, white flesh | Hot. If you like heat, you might like these. They were a little too hot for me. |
| Rat’s Tail | Grown for its edible seed pods instead of the root | Fun to grow, but I didn’t end up using the pods. |
When to Harvest Radishes
Most round radishes are ready about 3 to 4 weeks after sowing. Check your seed packet, since daikon and Black Spanish radishes take longer. Pull them when the root is about 1 inch across, about the size of a quarter. If you can see the top of the root at the soil line, brush away a little soil and check.
Don’t leave them in the ground long. Radishes left too long turn woody, hot, and pithy, and they’re more likely to split or bolt. Succession planting, or planting a few seeds every couple of weeks, gives you a steady supply instead of a pile all at once.
Why Aren’t My Radishes Bulbing?
| Problem | Usual cause | What to do |
|---|---|---|
| All leaves, no bulb | Too little sun, too crowded, too much nitrogen, or too warm | Plant in full sun, thin to 3 inches, skip nitrogen, and plant in cool weather |
| Split radishes | Uneven watering | Keep the soil evenly moist |
| Hot, woody, or pithy | Heat, dry soil, or left in the ground too long | Harvest on time and keep the water steady |
| Bolting (a tall flower stalk) | Warm weather | Plant earlier in the season |
| Small holes in the leaves | Flea beetles | Cover with floating row cover, or use insecticidal soap sparingly |
How I Eat Radishes
My favorite thing about growing radishes is pulling one at a time for a salad, instead of buying a whole bunch that goes bad in the fridge. I eat them raw in salads, and I’ve fermented them a few times. Cut the greens off before storing. Radishes keep 1 to 3 weeks in the refrigerator in produce storage containers.
You can also:
- Shred into slaws for a peppery crunch.
- Add to egg or potato salad for flavor.
- Toss into stir-fries or soups. Stir-fries and soups benefit from radishes’ subtle sweetness after cooking.
- Pickle or ferment for a probiotic-rich treat. They develop an irresistible tang and are perfect for beginners to try fermenting.
If you’re new to gardening, radishes are a quick way to get a harvest. Here are more easy vegetables for beginning gardeners.
Growing Radishes FAQs
Most round radishes are ready about 3 to 4 weeks after sowing. Daikon and Black Spanish radishes take longer, so check the seed packet.
Sun, steady water, and spacing. Give them at least 6 hours of sun, keep the soil evenly moist, and thin seedlings to 3 inches apart so the roots have room to form.
Yes. Round varieties like Cherry Belle grow well in a pot at least 6 inches deep. Keep the soil evenly moist, since pots dry out faster than garden beds.
No. Once the weather warms, radishes bolt and go to seed. Sow new seeds each season.
Not a new root. Radishes grow from seed. A radish left in the ground will flower and make seed pods, and you can save those seeds to plant later.
I have a new bed I have prepared for spring 2023… Can I go ahead and plant radishes in it for a cover crop? Thanks Angela.
I haven’t grown radishes as a cover crop, but I don’t see why you can’t. Now is a good time to plant in many areas.
What should I use to combat pests eating my radish leaves?
It’s probably flea beetles – they love radishes. You can try using insecticidal soap – but use it sparingly if at all. You could also try floating row cover. This blog post may be helpful: https://growinginthegarden.com/organic-pest-control-that-really-works/
How do you ferment radishes
I use these lids: https://amzn.to/3QM8sjD and the recipe in the booklet
Radishes are good for the bladder, herbalists say. For a morning-after (like, 1 January 🙂 eating a few is supposed to knock out the stomach problem, ease a headache and so on. Right now, October, is the best time to grow daikon and Black Schifferstadt in most of Arizona, both winter radishes, and make a good winter cover. Shifferstadt is called the poor man’s horseradish, and for that reason are good against nematodes. And, I hope pill bugs.
Great to know. Thanks for sharing.