GrowZone

ZIP 94612 planting calendar

When to plant watermelon in Oakland, CA - Zone 10a

In ZIP 94612, plant watermelon around Feb 15; this uses the Oakland frost station, USDA zone 10a, and watermelon timing rules.

Your Oakland calendar has a 303-day estimated frost-free season. This estimate uses the representative Oakland frost station, USDA zone 10a, and watermelon timing rules.

Source: oakland-intl frost station, USDA zone 10a, last updated 2026-06-28. Verify locally before planting high-value crops because microclimates, current weather, and yard exposure can move the safe date.

Reviewed by GrowZone Editorial. Calculated from the oakland-intl frost station and USDA zone 10a, last updated 2026-06-28.

In the Oakland area, watermelon timing follows the Oakland frost window, so the local ZIP date can differ from a broad zone-only calendar.

USDA zone 10a Oakland frost station University of California Agriculture and Natural Resources Updated 2026-06-28
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Answer first

When to start watermelon seeds indoors in Oakland

In ZIP 94612, start watermelon seeds indoors around Jan 11, about 21 days before the Feb 1 last-frost estimate.

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

Seed starting schedule

Watermelon dates for Oakland, CA

StepDateHow to use it
Start IndoorsJanuary 11, 2026Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsFebruary 15, 2026Move hardened-off seedlings outside after the frost-risk window.
Direct SowFebruary 15, 2026Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Oakland?

Oakland (ZIP 94612) has an average last spring frost around Feb 1.

First frost

When is the first frost in Oakland?

The average first fall frost is around Dec 1, giving about 303 frost-free days.

Season map

Watermelon windows by month

JanFebMarAprMayJunJulAugSepOctNovDec
Start indoors
Jan 11
Direct sow
Feb 15
Transplant
Feb 15
Harvest
May 16
Frost watch
Sep 2

Reminder workflow

Every date has a next action

Start watermelon indoorsJan 11
Last frost windowFeb 1
Direct sow watermelonFeb 15
Transplant watermelonFeb 15
First watermelon harvest windowMay 16
Last watermelon sowing targetSep 2
SignalValueWhy it matters
Last frost estimateFebruary 1, 2026Warm-season transplant risk starts falling after this window.
First frost estimateDecember 1, 2026Fall planting counts backward from this date.
Season length303 daysLonger seasons can support succession crops.
Spacing36-60 inAirflow and root space affect yield.
Soil temperature70 F+Seeds and transplants stall in cold soil.

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Local data

Why this date changes by ZIP

Oakland frost history and USDA zone 10a shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

University of California Agriculture and Natural Resources 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

Watermelon timing notes

Wait for warm soil; watermelon stalls when nights stay cool. Watermelon prefers full sun, 36-60 in spacing, and soil near 70 F+.

For fall, count backward from Dec 1. A conservative last sowing target is around Sep 2.