When should I plant radishes in ZIP 92101?

In ZIP 92101, the main radishes target is around Jan 2, based on the representative San Diego frost station and USDA zone 10b.

When should I start radishes seeds indoors in 92101?

Radishes is usually direct-sown for ZIP 92101. Use the Jan 2 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 92101 planting calendar

When to plant radishes in San Diego, CA - Zone 10b

Q: When is the first frost in San Diego?

San Diego (ZIP 92101) has an average first fall frost around Dec 15, leaving about 319 frost-free days.

In ZIP 92101, plant radishes around Jan 2; this uses the San Diego frost station, USDA zone 10b, and radishes timing rules.

Your San Diego calendar has a 319-day estimated frost-free season. This estimate uses the representative San Diego frost station, USDA zone 10b, and radishes timing rules.

Source: san-diego-lindbergh frost station, USDA zone 10b, last updated 2026-06-28. Verify locally before planting high-value crops because microclimates, current weather, and yard exposure can move the safe date.

USDA zone 10b San Diego frost station University of California Agriculture and Natural Resources Updated 2026-06-28

Read the method

Answer first

When to start radishes seeds indoors in San Diego

In ZIP 92101, radishes is usually direct-sown around Jan 2 instead of started indoors.

Radishes is normally direct-sown in San Diego. Use around Jan 2 as the outdoor planting window for ZIP 92101.

Seed starting schedule

Radishes dates for San Diego, CA

Step	Date	How to use it
Direct Sow	January 2, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in San Diego?

San Diego (ZIP 92101) has an average last spring frost around Jan 30.

First frost

When is the first frost in San Diego?

The average first fall frost is around Dec 15, giving about 319 frost-free days.

Season map

Radishes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Direct sow

Jan 2

Harvest

Jan 30

Frost watch

Nov 17

Reminder workflow

Every date has a next action

Direct sow radishesJan 2

Last frost windowJan 30

First radishes harvest windowJan 30

Last radishes sowing targetNov 17

Signal	Value	Why it matters
Last frost estimate	January 30, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	December 15, 2026	Fall planting counts backward from this date.
Season length	319 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

San Diego frost history and USDA zone 10b shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

University of California Agriculture and Natural Resources 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 Dec 15. A conservative last sowing target is around Nov 17.