FrostCal

When to Plant Watermelon in Idaho

In a typical Idaho location, start seeds indoors Apr 2 – Apr 9, then transplant outdoors May 14 – May 21. Across the state, the outdoor planting window starts as early as Apr 20 in Lewiston and as late as May 31 in Eagle. 2 cities in Idaho are essentially frost-free and can plant on a year-round schedule.

Method Start indoors, then transplant
Days to maturity 70–90 days

Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost.

Watermelon Planting Dates by City

CityStart indoorsTransplant
BoiseMar 27 – Apr 3May 8 – May 15
MeridianMar 27 – Apr 3May 8 – May 15
NampaApr 1 – Apr 8May 13 – May 20
Idaho FallsApr 11 – Apr 18May 23 – May 30
PocatelloApr 4 – Apr 11May 16 – May 23
CaldwellMar 26 – Apr 2May 7 – May 14
Coeur d'AleneMar 25 – Apr 1May 6 – May 13
Twin FallsApr 2 – Apr 9May 14 – May 21
LewistonMar 9 – Mar 16Apr 20 – Apr 27
Lewiston OrchardsMar 9 – Mar 16Apr 20 – Apr 27
Post FallsMar 25 – Apr 1May 6 – May 13
RexburgApr 17 – Apr 24May 29 – Jun 5
MoscowFrost-free: year-round planting
EagleApr 19 – Apr 26May 31 – Jun 7
CondaFrost-free: year-round planting
KunaMar 27 – Apr 3May 8 – May 15
AmmonApr 11 – Apr 18May 23 – May 30
ChubbuckApr 4 – Apr 11May 16 – May 23
HaydenMar 25 – Apr 1May 6 – May 13
Mountain HomeApr 4 – Apr 11May 16 – May 23
BlackfootApr 7 – Apr 14May 19 – May 26
Garden CityMar 27 – Apr 3May 8 – May 15
JeromeApr 4 – Apr 11May 16 – May 23
BurleyApr 9 – Apr 16May 21 – May 28

Showing the 24 most populous of 24 Idaho cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Idaho cities.

Frequently Asked Questions

When should I plant watermelon in Idaho?

In a typical Idaho location, start seeds indoors Apr 2 – Apr 9, then transplant outdoors May 14 – May 21. Across the state, the outdoor planting window starts as early as Apr 20 in Lewiston and as late as May 31 in Eagle. 2 cities in Idaho are essentially frost-free and can plant on a year-round schedule.

When is the last frost in Idaho?

The average last spring frost in Idaho ranges from April 6 in Lewiston to May 17 in Eagle, based on NOAA 1991–2020 climate normals.

How long do watermelon take to grow?

Watermelon typically take 70–90 days from planting to harvest. Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost.

Other Crops in Idaho

When to plant watermelon in other states

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