Question 1

When should I plant watermelon in ZIP 94102?

Accepted Answer

In ZIP 94102, the main watermelon target is around Feb 8, based on the representative San Francisco frost station and USDA zone 10a.

Question 2

When should I start watermelon seeds indoors in 94102?

Accepted Answer

Start watermelon seeds indoors in ZIP 94102 around Jan 4, about 21 days before the Jan 25 last-frost estimate.

Question 3

When is the last frost in San Francisco?

Accepted Answer

San Francisco (ZIP 94102) has an average last spring frost around Jan 25, based on the representative San Francisco frost station.

Question 4

When is the first frost in San Francisco?

Accepted Answer

San Francisco (ZIP 94102) has an average first fall frost around Dec 15, leaving about 324 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	January 4, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	February 8, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	February 8, 2026	Sow seed outside when the crop and soil can handle the window.

Start watermelon seeds indoors around Jan 4

Watermelon dates for San Francisco, CA