When to Plant Radishes: Spring and Fall Dates by City

Sow radish seed straight into the garden from about 3 weeks before your median last spring frost until 2 weeks after it. Frost does not hurt radishes; heat does. A crop that matures in hot weather often bolts and comes out hot, woody or hollow, so the spring season is a race to pull the roots before summer settles in.

The best radishes therefore come from two short seasons rather than one long one: a run of spring sowings that finish before the heat, and a second run in late summer that matures as fall cools. Round spring types need only 3 to 5 weeks, so each window has room for several sowings.

Radish planting dates by city

In Zones 3–8, each spring window opens 21 days before the city's median last frost and closes 14 days after it, and each fall window runs from 70 to 42 days before the median first fall frost. The Zone 9 rows give the local sowing season instead, which runs without a break.

Frost dates are medians from NOAA 1991–2020 climate normals for each city's main weather station, and zones are from the 2023 USDA map; in half of years the last frost falls later than the date shown.

For any other town in Zones 3–8, look up the median last and first frost dates for your nearest weather station. Count back 3 weeks and forward 2 weeks from the spring date, and back 10 to 6 weeks from the fall date; inside that span, the soil thermometer picks the day.

How the timing shifts by region

The farther south and the closer to a mild coast you garden, the more radishes shift from a spring-and-fall crop to one that grows straight through the winter.

Windows from state planting calendars; "one season" means sowing continues without a summer or winter break.

North and Upper Midwest (Zones 3–5)

In Minnesota, spring sowing runs from early April to early May and fall sowing from August 1 to September 1, within about a week of the Minneapolis row in the table. A typical summer there is hot enough to send radishes to flower and make the roots woody and fiery, so stop spring sowings when the window closes and pick up again in August. Fargo's fall window opens in late July because frost arrives by the end of September.

Midwest, Mid-Atlantic and Mountain West (Zones 6–7)

Missouri's calendar closes fall sowing between August 20 in the north and August 30 in the south, two to three weeks before the Kansas City row ends, so aim for the earlier dates there. In Utah, fall sowing starts in mid to late August. In Colorado, the first sowing can go in as much as 2 to 4 weeks before the last frost. In Maryland and similar climates, start as soon as the soil can be worked and keep a short row going in as often as every 5 days.

Southeast (Zones 7–9)

On the South Carolina coast the spring window opens about six weeks earlier than in the Piedmont (January 1 against February 15) and runs about twice as long. Late-spring sowings in this climate are the ones that bolt, so the spring season ends sooner than in the North. Fall sowing is the more forgiving run, because the roots size up as the weather cools; in central South Carolina it lasts nearly 8 weeks against 4 in spring.

Texas and the Gulf Coast

Texas sowings can run from 6 weeks before to 4 weeks after the last frost in spring, and from 8 weeks to 1 week before the first freeze in fall, a longer span than the Dallas-Fort Worth row. Average fall planting dates move from September 1 in the northernmost region to mid-December in Zone 9b, so around Houston the fall and spring runs meet in winter. Early fall can still be hot there: wait for a cooler spell if the soil is baking, because seed will not sprout in soil above 95°F (35°C).

Florida and the low desert (Zones 9–11)

Radishes here grow in a single cool season and are not sown in the hottest months; around Phoenix, nothing goes in from May through August. Sow every two weeks through each desert window and allow 30 to 60 days to harvest.

California and the Pacific Northwest

Sacramento's row follows the Central Valley season, which runs from September to April without a break. Coastal California and the Oregon coast can sow every month. West of the Cascades, radishes can be sown from March through September; a 40°F (4°C) soil reading decides the first sowing.

How to tell the soil is ready

Sow when a soil thermometer pushed 4 inches (10 cm) into the bed reads at least 40°F (4°C) at 8 a.m., before the sun warms the bed. The soil should also crumble in your hand rather than smear.

In workable soil, seedlings appear in 3 to 10 days; keep the seedbed damp and uncrusted until they are up.

There is no indoor head start to plan for. The root is the crop, and moving a seedling sets it back, so radishes are always sown where they will grow. For an earlier spring harvest, sow into a cold frame, window box or container in a sheltered spot in late winter instead.

How to sow radish seed

Radishes want loose soil, modest fertility, at least 6 hours of direct sun (8 to 10 is better) and steady moisture; they tolerate partial shade.

1. Loosen the bed. Fork the soil at least 6 inches (15 cm) deep for round radishes and about 12 inches (30 cm) for long daikon types, then rake it fine. In heavy clay, a raised bed gives the roots loose soil to swell in.
2. Keep fertility low. Excess nitrogen builds big leaves over small roots, so skip the manure and fertilize lightly, or only as a soil test directs. Aim for a pH of 6.0 to 7.0.
3. Sow shallow and thin. Cover seed 1/4 to 1/2 inch (6–13 mm) deep, or up to 1 inch (2.5 cm) for large daikons. Space seeds about 1 inch (2.5 cm) apart in rows 10 to 24 inches (25–60 cm) apart, which means less thinning later.
4. Cover the row. Lay floating row cover over the row on sowing day so flea beetles and cabbage root maggots cannot reach the seedlings.
5. Thin at two true leaves. Pull or snip extras so round and French types stand 2 to 3 inches (5–7.5 cm) apart and daikons 4 to 6 inches (10–15 cm). Crowded radishes make small, misshapen roots or none at all.
6. Water evenly. Give about 1 inch (2.5 cm) a week, and more often on sand. Dry spells followed by a soaking crack the roots, and a radish that grows slowly for lack of water turns hot and pithy.

Radish types and how they change the timing

A variety's speed and heat tolerance decide how much of each window you can use, and the large Asian types belong to late summer rather than spring.

Days to maturity are seed-company figures from direct sowing to harvest.

Rover, listed at 21 days, suits a short northern spring. Cherry Belle is a small, scarlet round grown in most regions, and in the Southeast Scarlet Globe and Cherriette are good red rounds too. When the spring window is nearly over, switch to French Breakfast, the white Icicle type or Rover, which cope with rising temperatures better than other early radishes. Radishes grow best in relatively short days of 10 to 12 hours and temperatures of 50 to 70°F (10–21°C). Late spring brings long days and rising heat together, which is where ordinary varieties fail, while a fall sowing matures as the days shorten and cool.

Daikon and other winter radishes take far longer and grow far bigger: a daikon can reach 18 inches (45 cm) long and 5 to 6 pounds (2.3–2.7 kg). Sow most of them from midsummer into late summer so they size up in fall, and treat watermelon radishes the same way, since Red Meat is likely to bolt if sown in spring. Small Korean hybrids such as Mini Mak are the exception, with enough bolt tolerance for spring and summer sowings.

Succession and fall sowings

Sow a short row every 7 to 14 days through each window instead of one long row, because radishes go pithy within days of reaching full size.

Match the row length to what your household eats in a week or so. Three sowings 10 to 14 days apart fill the 5-week spring window. Stop when the window closes, not when the seed packet runs out.

The fall window opens 10 weeks before the median first fall frost and closes 6 weeks before it. Fall radishes start in warm soil and finish in cool air, the reverse of spring, so the roots size up as temperatures drop into the range they prefer. Sow daikons and watermelon radishes at the start of the window, since they need far longer than round types.

Winter types also keep. Pulled before the ground freezes, winter radishes and daikons keep for up to several months in moist, cold storage near 32°F (0°C), but only a week or two in a fridge crisper; Red Meat lasts 6 to 10 weeks at 32°F (0°C). When the last fall radishes come out, the bed is free for fall-planted garlic.

What goes wrong when you sow too early or too late

Sowing too early mostly wastes seed, while sowing too late wastes the crop.

Too early. Below 40°F (4°C), radish barely grows, so seed sown into frozen or cold, wet ground is slow to come up, and the early start buys little. Frost on the seedlings is not the risk; cold soil is. Wait for the soil reading rather than the calendar.

Too late in spring. A crop that matures above 80°F (27°C) often bolts, and the roots are more often deformed, woody, hollow or fiery. Stress in the first 6 weeks, from heat or dry soil, can also push plants to flower early. If the window has closed, sow Mini Mak or wait for the late-summer sowing.

Too hot in late summer. In the South and the deserts, seed sown into soil above 95°F (35°C) will not sprout. Hold off until the heat breaks.

Too late in fall. A sowing made after the window closes grows slowly as the soil cools toward 40°F (4°C), and the roots may still be small when a hard freeze arrives.

Left too long. Even a well-timed crop fails if it stays in the ground. Mature roots crack, go pithy and turn hot within days, which is why small, frequent sowings beat one big one.

Frost, harvest and what to expect

Radishes are hardy: heavy frosts in spring and fall do them no real damage, so a late cold snap is no reason to resow, and no frost protection is needed; leave the insect cover in place.

The one exception is a hard freeze on a mature crop: pull fall roots before the ground freezes hard.

Expect seedlings in 3 to 10 days and the first round radishes 3 to 4 weeks after sowing. Brush the soil from the shoulder of a root to check its size, and pull red radishes before they pass about 1 inch (2.5 cm) across and white ones before about 3/4 inch (2 cm). Roots left past that point lose their crispness quickly.

To fit radishes around the rest of your spring and fall crops, compare the planting dates for other vegetables and add your sowing windows to Sow's garden calendar.