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ZIP 73102 planting calendar

When to plant watermelon in Oklahoma City, OK - Zone 7b

In ZIP 73102, plant watermelon around Apr 19; this uses the Oklahoma City frost station, USDA zone 7b, and watermelon timing rules.

Your Oklahoma City calendar has a 208-day estimated frost-free season. This estimate uses the representative Oklahoma City frost station, USDA zone 7b, and watermelon timing rules.

Source: oklahoma-city-will-rogers frost station, USDA zone 7b, 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 oklahoma-city-will-rogers frost station and USDA zone 7b, last updated 2026-06-28.

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

USDA zone 7b Oklahoma City frost station Oklahoma State University Extension Updated 2026-06-28
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Answer first

When to start watermelon seeds indoors in Oklahoma City

In ZIP 73102, start watermelon seeds indoors around Mar 15, about 21 days before the Apr 5 last-frost estimate.

Start watermelon seeds indoors in Oklahoma City around Mar 15, about 21 days before the Apr 5 last-frost estimate.

Seed starting schedule

Watermelon dates for Oklahoma City, OK

StepDateHow to use it
Start IndoorsMarch 15, 2026Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsApril 19, 2026Move hardened-off seedlings outside after the frost-risk window.
Direct SowApril 19, 2026Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Oklahoma City?

Oklahoma City (ZIP 73102) has an average last spring frost around Apr 5.

First frost

When is the first frost in Oklahoma City?

The average first fall frost is around Oct 30, giving about 208 frost-free days.

Season map

Watermelon windows by month

JanFebMarAprMayJunJulAugSepOctNovDec
Start indoors
Mar 15
Direct sow
Apr 19
Transplant
Apr 19
Harvest
Jul 18
Frost watch
Aug 1

Reminder workflow

Every date has a next action

Start watermelon indoorsMar 15
Last frost windowApr 5
Direct sow watermelonApr 19
Transplant watermelonApr 19
First watermelon harvest windowJul 18
Last watermelon sowing targetAug 1
SignalValueWhy it matters
Last frost estimateApril 5, 2026Warm-season transplant risk starts falling after this window.
First frost estimateOctober 30, 2026Fall planting counts backward from this date.
Season length208 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

Oklahoma City frost history and USDA zone 7b shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

Oklahoma State University Extension 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 Oct 30. A conservative last sowing target is around Aug 1.