Plant Radishes in Zone 6b
Seed-starting, transplant & harvest dates for USDA Zone 6b
Zone 6b averages 186 frost-free days, running from a last spring frost around April 15 to a first fall frost around October 18. Radishes needs roughly 28 days from planting out to first harvest, so it uses about 15 percent of that window. Radishes is a hardy crop, which is what decides where in the window it belongs.
Radishes handles cold soil, so there is no reason to wait for the frost date. Direct sow around Mar 18, roughly 4 weeks before the Zone 6b last frost, as soon as the ground is workable. Sowing at the last frost instead costs you the coolest and best part of the season. At 28 days to harvest, a 186-day Zone 6b season has room for about 4 sowings, so stagger them rather than planting everything at once.
Planting radishes for a fall harvest in Zone 6b
Yes. Sow radishes by September 27 in Zone 6b. That is 21 days before the average first frost, which covers the 28 days to maturity plus about two weeks for the slower growth that comes with shortening days, minus the roughly 21 days radishes keeps going once light frost arrives.
Radishes are the fastest fall insurance crop. Fall roots stay milder and split less than spring ones because the soil is cooling rather than heating.
Fall dates are counted backward from the Zone 6b average first frost, not forward from a sowing date. See the fall planting calendar by zone for the full method.
Spring vs fall radishes in Zone 6b
| Planting | Sow or start | In the ground | Harvest |
|---|---|---|---|
| Spring | Mar 18 | Mar 18 | Apr 15 |
| Fall | by Sep 27 | Sep 27 | Oct 25 |
Radishes in nearby zones
Further reading on radishes
- Cold frame gardening by zone
How a cold frame keeps radishes producing into winter, and when to sow it.
- Last frost date and what to plant before it
Why radishes can go out before your last frost, and how far before.
- Best raised garden beds for beginners
Loose, deep soil is most of what root crops need.
Other crops in Zone 6b
Frequently asked questions
When should I start radishes in Zone 6b?
Direct sow outdoors around Mar 18.
Can I direct sow radishes in Zone 6b?
Yes, direct sow around Mar 18.
Can I plant radishes in the fall in Zone 6b?
Yes. Sow radishes by September 27 in Zone 6b. That is 21 days before the average first frost, which covers the 28 days to maturity plus about two weeks for the slower growth that comes with shortening days, minus the roughly 21 days radishes keeps going once light frost arrives.
Will radishes survive frost in Zone 6b?
Radishes is a hardy crop and keeps going roughly 21 days past the first light frost in Zone 6b. A row cover or a straw mulch buys more.
How many plantings of radishes fit in a Zone 6b season?
About 4. Zone 6b averages 186 frost-free days and radishes needs roughly 28 days plus a couple of weeks of turnaround, so sowing every 21 days keeps a supply coming.