Question 1

When should I plant watermelon in ZIP 96813?

Accepted Answer

In ZIP 96813, the main watermelon target is around Jan 15, based on the representative Honolulu frost station and USDA zone 12b.

Question 2

When should I start watermelon seeds indoors in 96813?

Accepted Answer

Start watermelon seeds indoors in ZIP 96813 around Dec 11, about 21 days before the Jan 1 last-frost estimate.

Question 3

When is the last frost in Honolulu?

Accepted Answer

Honolulu (ZIP 96813) has an average last spring frost around Jan 1, based on the representative Honolulu frost station.

Question 4

When is the first frost in Honolulu?

Accepted Answer

Honolulu (ZIP 96813) has an average first fall frost around Dec 31, leaving about 364 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	December 11, 2025	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	January 15, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	January 15, 2026	Sow seed outside when the crop and soil can handle the window.

Start watermelon seeds indoors around Dec 11

Watermelon dates for Honolulu, HI