When to plant radishes in Alaska
Alaska’s average last spring frost is May 17, and the first fall frost typically arrives around September 13 — about 119 frost-free days (USDA zones 1a, 2b, 3b, 4b, 5b, 6b, 7b, 8b). Radish needs 22–30 days to mature, which fits comfortably within Alaska's growing season.
Alaska covers a wide range of climates, so your exact frost dates may differ from the state average by two weeks or more. For dates tuned to your town, use the calendar generator.
When to plant radishes in Alaska: the short answer
For a spring planting, sow Apr 14 – May 3. Seeds germinate in soil from 40 to 85°F.
Succession sow again in Alaska: Apr 29 · May 9 · May 19 · May 29 · Jun 8 · Jun 18
Spring succession stops before summer heat makes it bolt. Start sowing again in late summer for a fall crop (see the fall window above).
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow radishes in Alaska, step by step
- Prepare the bed. They need six or more hours of sun for the best growth, though four to six hours in partial shade is enough and loose soil at least 6 inches deep, with a pH between 6.0 and 7.0. Dig in compost before planting.
- Sow outdoors (Apr 14 – May 3). Space plants about 2 inches apart in rows 6 inches apart, sowing seed ½ inch deep. It handles frost well, so it can go out before the last frost date. As a cool-season crop it does best before summer heat arrives in Alaska.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: flea beetle, cabbage root maggot, aphids. Diseases and disorders: clubroot, scab, downy mildew.
- Harvest (from about May 11 – May 19). Radish takes 22-30 days to reach harvest. The classic marker crop and quick filler. Sow a short row every 10 days - a single big sowing all matures at once and then goes pithy and hot.
Figures come from our crop data; dates use Alaska’s average frost dates. More in the full radish growing guide.
Radish planting dates by USDA zone in Alaska
Alaska spans USDA zones 1a, 2b, 3b, 4b, 5b, 6b, 7b, 8b. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average, so the radish dates shift with them.
| Zone | Last frost | First frost | Season | Start indoors | Plant radish |
|---|---|---|---|---|---|
| Zone 1 | Jun 15 | Aug 20 | 65 days | - | May 13 – Jun 1 |
| Zone 2 | Jun 1 | Sep 1 | 90 days | - | Apr 29 – May 18 |
| Zone 3 | May 15 | Sep 15 | 120 days | - | Apr 12 – May 1 |
| Zone 4 | May 10 | Sep 25 | 135 days | - | Apr 7 – Apr 26 |
| Zone 5 | Apr 30 | Oct 5 | 160 days | - | Mar 28 – Apr 16 |
| Zone 6 | Apr 15 | Oct 15 | 185 days | - | Mar 13 – Apr 1 |
| Zone 7 | Apr 5 | Oct 25 | 200 days | - | Mar 3 – Mar 22 |
| Zone 8 | Mar 20 | Nov 5 | 230 days | - | Feb 15 – Mar 6 |
When to plant radishes in nearby states
| State | Last frost | Sow |
|---|---|---|
| Alaska (this page) | May 17 | Apr 14 – May 3 |
| Hawaii | frost-free | - |
Questions gardeners in Alaska ask
When is the best time to plant radishes in Alaska?
Sow radishes in Alaska between April 14 and May 3. That timing is set by Alaska's average last spring frost of May 17; Alaska spans several climates, so cooler and higher parts of the state run later.
Can I plant radishes in the fall in Alaska?
Yes. For a fall crop, sow between July 30 and August 16, so the crop matures in cool weather before Alaska's first frost around September 13.
When will radishes planted in Alaska be ready to harvest?
Planted on time, radishes are usually ready from about May 11 to May 19, 22-30 days after sowing.
When is the last frost in Alaska?
On average around May 17, with the first fall frost around September 13 - about 119 frost-free days. Your town may differ by two weeks or more.