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When to plant watermelon in Zone 4b
Your watermelon timeline — Zone 4b
| Start indoors | April 26 – May 3 |
|---|---|
| Transplant | May 17 – May 31 |
| Zone 4b last frost | ~05/10 |
| Zone 4b first frost | ~09/30 |
Dates computed from Zone 4b's median NOAA frost normals and the cited rule. Your town may differ by a week or two — check your exact ZIP.
What you'll need
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Seed-starting traysBurpee SuperSeed 36-cell trayReusable cells that pop seedlings out with the roots intact at transplant time.See it on Amazon- Seed-starting mixEspoma Organic Seed StarterA fine, sterile mix so small seeds can push through and seedlings don't rot.See it on Amazon
- Heat matVIVOSUN heat mat with thermostatWarm-season seeds sprout in days instead of weeks when the soil sits near 75–85°F.See it on Amazon
- Grow lightBarrina T5 LED grow lights, 4-packA windowsill is too dim in late winter; a light 2–3 in. above keeps seedlings short and sturdy.See it on Amazon
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Calendar computed 2026-09-28. Frost: NOAA NCEI 1991–2020. Zone: USDA 2023. Rule: Johnny's Selected Seeds — Seed-Starting Date Calculator chart; University of Georgia Extension — Vegetable Planting Chart (Circular C963) (days to maturity).