When should I plant radishes in ZIP 98101?

In ZIP 98101, the main radishes target is around Feb 20, based on the representative Seattle frost station and USDA zone 9a.

When should I start radishes seeds indoors in 98101?

Radishes is usually direct-sown for ZIP 98101. Use the Feb 20 planting window instead of starting it indoors.

Is this a guaranteed planting date?

No. GrowZone uses frost-date estimates, hardiness zones, and crop timing rules for planning. Local microclimates and current weather can shift the right date.

ZIP 98101 planting calendar

When to plant radishes in Seattle, WA - Zone 9a

Q: When is the first frost in Seattle?

Seattle (ZIP 98101) has an average first fall frost around Nov 20, leaving about 245 frost-free days.

In ZIP 98101, plant radishes around Feb 20; this uses the Seattle frost station, USDA zone 9a, and radishes timing rules.

Your Seattle calendar has a 245-day estimated frost-free season. This estimate uses the representative Seattle frost station, USDA zone 9a, and radishes timing rules.

Source: seattle-tacoma frost station, USDA zone 9a, last updated 2026-06-28. Verify locally before planting high-value crops because microclimates, current weather, and yard exposure can move the safe date.

Reviewed by GrowZone Editorial. Calculated from the seattle-tacoma frost station and USDA zone 9a, last updated 2026-06-28.

In the Seattle area, radishes timing follows the Seattle frost window, so the local ZIP date can differ from a broad zone-only calendar.

USDA zone 9a Seattle frost station Washington State University Extension Updated 2026-06-28

Read the method

Answer first

When to start radishes seeds indoors in Seattle

In ZIP 98101, radishes is usually direct-sown around Feb 20 instead of started indoors.

Radishes is normally direct-sown in Seattle. Use around Feb 20 as the outdoor planting window for ZIP 98101.

Seed starting schedule

Radishes dates for Seattle, WA

Step	Date	How to use it
Direct Sow	February 20, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Seattle?

Seattle (ZIP 98101) has an average last spring frost around Mar 20.

First frost

When is the first frost in Seattle?

The average first fall frost is around Nov 20, giving about 245 frost-free days.

Season map

Radishes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Direct sow

Feb 20

Harvest

Mar 20

Frost watch

Oct 23

Reminder workflow

Every date has a next action

Direct sow radishesFeb 20

Last frost windowMar 20

First radishes harvest windowMar 20

Last radishes sowing targetOct 23

Signal	Value	Why it matters
Last frost estimate	March 20, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	November 20, 2026	Fall planting counts backward from this date.
Season length	245 days	Longer seasons can support succession crops.
Spacing	1-2 in	Airflow and root space affect yield.
Soil temperature	40 F+	Seeds and transplants stall in cold soil.

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Local data

Why this date changes by ZIP

Seattle frost history and USDA zone 9a shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

Washington State University Extension is the kind of local source to verify against when a crop is expensive, weather is unusual, or your yard has a cold pocket.

Crop note

Radishes timing notes

Fast crop; harvest promptly before roots get woody. Radishes prefers full sun, 1-2 in spacing, and soil near 40 F+.

For fall, count backward from Nov 20. A conservative last sowing target is around Oct 23.