When should I plant spinach in ZIP 19103?

In ZIP 19103, the main spinach target is around Mar 13, based on the representative Philadelphia frost station and USDA zone 7b.

When should I start spinach seeds indoors in 19103?

Spinach is usually direct-sown for ZIP 19103. Use the Mar 13 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 19103 planting calendar

When to plant spinach in Philadelphia, PA - Zone 7b

Q: When is the first frost in Philadelphia?

Philadelphia (ZIP 19103) has an average first fall frost around Nov 5, leaving about 209 frost-free days.

In ZIP 19103, plant spinach around Mar 13; this uses the Philadelphia frost station, USDA zone 7b, and spinach timing rules.

Your Philadelphia calendar has a 209-day estimated frost-free season. This estimate uses the representative Philadelphia frost station, USDA zone 7b, and spinach timing rules.

Source: philadelphia-intl frost station, USDA zone 7b, 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 7b Philadelphia frost station Penn State Extension Updated 2026-06-28

Read the method

Answer first

When to start spinach seeds indoors in Philadelphia

In ZIP 19103, spinach is usually direct-sown around Mar 13 instead of started indoors.

Spinach is normally direct-sown in Philadelphia. Use around Mar 13 as the outdoor planting window for ZIP 19103.

Seed starting schedule

Spinach dates for Philadelphia, PA

Step	Date	How to use it
Direct Sow	March 13, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Philadelphia?

Philadelphia (ZIP 19103) has an average last spring frost around Apr 10.

First frost

When is the first frost in Philadelphia?

The average first fall frost is around Nov 5, giving about 209 frost-free days.

Season map

Spinach windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Direct sow

Mar 13

Harvest

Apr 27

Frost watch

Sep 21

Reminder workflow

Every date has a next action

Direct sow spinachMar 13

Last frost windowApr 10

First spinach harvest windowApr 27

Last spinach sowing targetSep 21

Signal	Value	Why it matters
Last frost estimate	April 10, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	November 5, 2026	Fall planting counts backward from this date.
Season length	209 days	Longer seasons can support succession crops.
Spacing	4-6 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

Philadelphia frost history and USDA zone 7b shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

Penn State 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

Spinach timing notes

Plant early and again in late summer for fall leaves. Spinach prefers sun to part shade, 4-6 in spacing, and soil near 40 F+.

For fall, count backward from Nov 5. A conservative last sowing target is around Sep 21.