Question 1

When should I plant zucchini in ZIP 19103?

Accepted Answer

In ZIP 19103, the main zucchini target is around Apr 20, based on the representative Philadelphia frost station and USDA zone 7b.

Question 2

When should I start zucchini seeds indoors in 19103?

Accepted Answer

Start zucchini seeds indoors in ZIP 19103 around Mar 20, about 21 days before the Apr 10 last-frost estimate.

Question 3

When is the last frost in Philadelphia?

Accepted Answer

Philadelphia (ZIP 19103) has an average last spring frost around Apr 10, based on the representative Philadelphia frost station.

Question 4

When is the first frost in Philadelphia?

Accepted Answer

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

Question 5

Is this a guaranteed planting date?

Accepted Answer

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

Step	Date	How to use it
Start Indoors	March 20, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	April 20, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	April 20, 2026	Sow seed outside when the crop and soil can handle the window.

Start zucchini seeds indoors around Mar 20

Zucchini dates for Philadelphia, PA