Question 1

When should I plant watermelon in ZIP 97204?

Accepted Answer

In ZIP 97204, the main watermelon target is around Apr 15, based on the representative Portland frost station and USDA zone 9a.

Question 2

When should I start watermelon seeds indoors in 97204?

Accepted Answer

Start watermelon seeds indoors in ZIP 97204 around Mar 11, about 21 days before the Apr 1 last-frost estimate.

Question 3

When is the last frost in Portland?

Accepted Answer

Portland (ZIP 97204) has an average last spring frost around Apr 1, based on the representative Portland frost station.

Question 4

When is the first frost in Portland?

Accepted Answer

Portland (ZIP 97204) has an average first fall frost around Nov 10, leaving about 223 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 11, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	April 15, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	April 15, 2026	Sow seed outside when the crop and soil can handle the window.

Start watermelon seeds indoors around Mar 11

Watermelon dates for Portland, OR