Many people enjoy radishes as a salad garnish, while others prefer to roast these crisp, peppery roots until tender and buttery. Either way, radishes are a delicious vegetable that you can grow yourself right at home. But when exactly should you plant radishes?
The best time to plant radishes is in spring after all the risk of frost has passed — that’s when the ground is workable and the roots can develop without stress. You can also plant them in the fall, 4-6 weeks before the first frost date. Don’t sow when temperatures rise to 70 ˚F or above.
Most people don’t realize that you can plant radishes multiple times in their growing season and then harvest them just a couple of weeks later. Let’s get started so you know when to plant radishes, where to plant them, and how best to prepare the soil.
When’s the Best Time to Plant Radishes?
The best time to plant radishes is in spring after the ground has thawed. They’ll sprout quickly in spring temperatures ranging from 45 to 70 ˚F (7-21 ˚C).
While radishes can grow in cool temperatures, you should plant them when the soil is warm enough so the roots don’t get stressed.
As it turns out, roots that develop under less stressful conditions usually grow more tender, juicy, and flavorful radishes. Moreover, waiting until the risk of spring frost has passed allows you to plant when the ground is workable.
Since radishes mature relatively quickly, you can use them to mark lines of slower germinating summer crops like carrots and beets.
Try planting the radish seeds (on Amazon) every week or so, as successive sowings in the spring will ensure you have continuous bountiful harvests with no hunger gaps.
Stop sowing when warmer temperatures arrive — typically anything above 70 ˚F is too high. Otherwise, the plants will simply wilt or bolt sooner than you expect and become useless.
While the best time to plant radishes is in the spring, you can also sow them in the fall, some 4 to 6 weeks before the first expected frost. And if you prefer to plant in the fall, experts advise you go with selected winter varieties, particularly daikons like the China Rose (on Amazon).
The Best Month to Plant Radishes Outdoors
April is usually the prime month for planting radishes outdoors, since the chilly temperatures have usually given way to the warmth of spring and the ground has warmed enough.
You can still grow radishes past April once the risk of spring frost has passed, but be sure to check local weather conditions. Nonetheless, you don’t want to grow radishes outside in the summer, as the dizzying heat will make them wilt or bolt and go to seed.
Here are some key tips for sowing radishes outdoors:
- Sow the seeds about 1/2 inch deep in rows 12 inches apart.
- Cover the seeds lightly with soil and water them deeply.
- Sow another round of seeds every 7 to 10 days when the weather is still cool to enjoy a continuous harvest in the late spring and early summer.
The Best Time to Plant Radishes Under Cover
There’s no specific time for growing radishes under cover, as you can sow them indoors under favorable conditions all year round.
As temperatures begin to dip in colder regions, you can plant radishes from late fall and throughout the winter in a heated propagator or greenhouse. If you plant them in a greenhouse during summer, be sure to water them thoroughly.
Can Radishes Grow Year Round?
Radishes are annuals, meaning they won’t grow year-round; instead, they complete their life cycle within one growing season.
Unlike perennials such as rhubarb, annual veggies like radishes usually die in the winter season and you must replant them every year.
So if for some reason you’re looking to grow radishes all year round, your ideal option is to plant them in a greenhouse.
In Which Climate Do Radishes Grow Best?
Radishes grow best in cooler temperate climates, making them one of the most preferred annuals among northern gardeners. They’re tolerant to cold weather and will mature quickly in USDA zones 2 -10.
Being a cool season crop, radishes do well in the optimum temperature range of 60-65 ˚F. However, they can withstand temperatures as low as 45 ˚F.
If the temperature drops lower than that, the seeds will likely have a hard time germinating. And if the temperature exceeds 70 ℉, the roots start becoming woody and pitchy.
Moreover, they’ll want to bolt and go to seed, leaving you with no meaningful amount of roots to harvest.
How to Prepare Your Soil to Grow Radishes
Radishes are hardy root veggies, and you shouldn’t have too tough of a time preparing the soil to grow them.
They do well in any well-drained, slightly acidic, or neutral soil that’s not compacted (roots don’t like compacted soil).
Follow these tips to prepare the soil for growing radishes:
- Test the soil with a soil test kit (on Amazon) to confirm if its pH is within the slightly acidic to neutral range (pH of 6-7).
- Till the soil, removing rocks and other hard materials that can come in the way of the roots. While varieties like daikons (winter radishes) can penetrate as much as 12 inches in heavy soils, their roots won’t be smooth, uniform, and tender. If your soil is much compacted or considerably rocky, choose shorter daikon varieties.
- If you’re planting longer varieties of radishes like White Icicle (on Amazon), be sure to till the soil to a depth of around 8 inches (0.7 feet). Lighter, well-prepared soils ensure the roots are smoother, tender, and more uniform.
- If the soil is clay, work in well-rotted compost or manure in the spring or autumn. Don’t use fresh organic manure as it can scorch the plants. Moreover, it may contain harmful bacteria and seeds of weeds that will quickly choke and kill your radishes as soon as they sprout.
- Avoid fertilizers high in nitrogen as they’ll only encourage lush foliage at the expense of those flavorful, crisp, radish roots.
Do Radishes Prefer Sun or Shade?
Radishes prefer full sun to grow, and you should choose a spot that receives at least 6 hours of sunshine per day.
Even though radishes do well in sunny conditions, you should ensure the soil is adequately moist (not waterlogged) to reap those beautiful clusters of mildly peppery roots in plenty.
If you grow radishes in warmer southern states, be sure to give the plants partial shade in the middle of the summer heat. Not only does it protect them from wilting, but it also ensures you can grow the plants farther into the growing season.
Still, don’t give them too much shade, and don’t plant them where neighboring plants could cover them too much, blocking them from sunlight.
Too much shade makes the plants concentrate more of their energy on producing larger leaves, which you don’t want anyway. Finding a balance is key!