When to plant radishes in Delaware
Delaware’s average last spring frost is April 14, and the first fall frost typically arrives around October 22 — about 191 frost-free days (USDA zones 7a, 7b). Radish needs 22–30 days to mature, which fits comfortably within Delaware's growing season.
When to plant radishes in Delaware: the short answer
For a spring planting, sow Mar 12 – Mar 31. Seeds germinate in soil from 40 to 85°F.
Succession sow again in Delaware: Mar 27 · Apr 6 · Apr 16 · Apr 26 · May 6 · May 16
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 Delaware, 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 (Mar 12 – Mar 31). 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 Delaware.
- 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 Apr 8 – Apr 16). 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 Delaware’s average frost dates. More in the full radish growing guide.
When to plant radishes in nearby states
| State | Last frost | Sow |
|---|---|---|
| Delaware (this page) | April 14 | Mar 12 – Mar 31 |
| New Jersey | April 20 | Mar 18 – Apr 6 |
| Pennsylvania | May 1 | Mar 29 – Apr 17 |
| Maryland | April 14 | Mar 12 – Mar 31 |
| District of Columbia | April 10 | Mar 8 – Mar 27 |
| Virginia | April 15 | Mar 13 – Apr 1 |
| West Virginia | May 5 | Apr 2 – Apr 21 |
Questions gardeners in Delaware ask
When is the best time to plant radishes in Delaware?
Sow radishes in Delaware between March 12 and March 31. That timing is set by Delaware's average last spring frost of April 14.
Can I plant radishes in the fall in Delaware?
Yes. For a fall crop, sow between September 7 and September 24, so the crop matures in cool weather before Delaware's first frost around October 22.
When will radishes planted in Delaware be ready to harvest?
Planted on time, radishes are usually ready from about April 8 to April 16, 22-30 days after sowing.
When is the last frost in Delaware?
On average around April 14, with the first fall frost around October 22 - about 191 frost-free days. Your town may differ by two weeks or more.