When should I plant radishes in ZIP 78205?

In ZIP 78205, the main radishes target is around Feb 1, based on the representative San Antonio frost station and USDA zone 9a.

When should I start radishes seeds indoors in 78205?

Radishes is usually direct-sown for ZIP 78205. Use the Feb 1 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 78205 planting calendar

When to plant radishes in San Antonio, TX - Zone 9a

Q: When is the first frost in San Antonio?

San Antonio (ZIP 78205) has an average first fall frost around Nov 20, leaving about 264 frost-free days.

In ZIP 78205, plant radishes around Feb 1; this uses the San Antonio frost station, USDA zone 9a, and radishes timing rules.

Your San Antonio calendar has a 264-day estimated frost-free season. This estimate uses the representative San Antonio frost station, USDA zone 9a, and radishes timing rules.

Source: san-antonio-intl 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.

USDA zone 9a San Antonio frost station Texas A&M AgriLife Extension Updated 2026-06-28

Read the method

Answer first

When to start radishes seeds indoors in San Antonio

In ZIP 78205, radishes is usually direct-sown around Feb 1 instead of started indoors.

Radishes is normally direct-sown in San Antonio. Use around Feb 1 as the outdoor planting window for ZIP 78205.

Seed starting schedule

Radishes dates for San Antonio, TX

Step	Date	How to use it
Direct Sow	February 1, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in San Antonio?

San Antonio (ZIP 78205) has an average last spring frost around Mar 1.

First frost

When is the first frost in San Antonio?

The average first fall frost is around Nov 20, giving about 264 frost-free days.

Season map

Radishes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Direct sow

Feb 1

Harvest

Mar 1

Frost watch

Oct 23

Reminder workflow

Every date has a next action

Direct sow radishesFeb 1

Last frost windowMar 1

First radishes harvest windowMar 1

Last radishes sowing targetOct 23

Signal	Value	Why it matters
Last frost estimate	March 1, 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	264 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 Antonio frost history and USDA zone 9a shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

Texas A&M AgriLife 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.