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ZIP 90012 planting calendar

When to plant watermelon in Los Angeles, CA - Zone 10b

In ZIP 90012, plant watermelon around Feb 3; this uses the Los Angeles frost station, USDA zone 10b, and watermelon timing rules.

Your Los Angeles calendar has a 329-day estimated frost-free season. This estimate uses the representative Los Angeles frost station, USDA zone 10b, and watermelon timing rules.

Source: los-angeles-civic-center frost station, USDA zone 10b, 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 los-angeles-civic-center frost station and USDA zone 10b, last updated 2026-06-28.

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

USDA zone 10b Los Angeles 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 Los Angeles

In ZIP 90012, start watermelon seeds indoors around Dec 30, about 21 days before the Jan 20 last-frost estimate.

Start watermelon seeds indoors in Los Angeles around Dec 30, about 21 days before the Jan 20 last-frost estimate.

Seed starting schedule

Watermelon dates for Los Angeles, CA

StepDateHow to use it
Start IndoorsDecember 30, 2025Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsFebruary 3, 2026Move hardened-off seedlings outside after the frost-risk window.
Direct SowFebruary 3, 2026Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Los Angeles?

Los Angeles (ZIP 90012) has an average last spring frost around Jan 20.

First frost

When is the first frost in Los Angeles?

The average first fall frost is around Dec 15, giving about 329 frost-free days.

Season map

Watermelon windows by month

JanFebMarAprMayJunJulAugSepOctNovDec
Start indoors
Dec 30
Direct sow
Feb 3
Transplant
Feb 3
Harvest
May 4
Frost watch
Sep 16

Reminder workflow

Every date has a next action

Start watermelon indoorsDec 30
Last frost windowJan 20
Direct sow watermelonFeb 3
Transplant watermelonFeb 3
First watermelon harvest windowMay 4
Last watermelon sowing targetSep 16
SignalValueWhy it matters
Last frost estimateJanuary 20, 2026Warm-season transplant risk starts falling after this window.
First frost estimateDecember 15, 2026Fall planting counts backward from this date.
Season length329 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

Los Angeles frost history and USDA zone 10b 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 15. A conservative last sowing target is around Sep 16.