US Lawn & Growing Season Insights
National analysis of growing seasons, hardiness zones, and lawn climate patterns across all 3,144 US counties. Data from NOAA NCEI 1991-2020 Climate Normals and USDA PHZM.
National Avg Season
191 days
National Avg Temp
54.8°F
Counties Analyzed
2,728
Key Findings
Growing season length varies dramatically across the United States. Florida leads with an average of 275 days, while Montana averages just 122 days. This 153-day spread means lawn care strategies must be highly localized.
Nationally, counties average 191 days between the last spring frost and first fall frost. Warmer southern counties often see 250+ day seasons, while northern mountain counties may have fewer than 100 frost-free days — a critical factor when selecting grass species and planning seeding calendars.
State Growing Season Rankings
Average frost-free days by state, computed from all counties with data. Southern and coastal states dominate the top, while northern and mountain states anchor the bottom.
Longest Seasons
Shortest Seasons
Growing Season Distribution
How US counties are distributed across growing season lengths. Most counties fall in the 150-250 day range, with a long tail of short-season counties in the northern mountains and Alaska.
Temperature vs. Growing Season
Each point is a US county. Warmer counties almost always have longer growing seasons, but the relationship is non-linear due to altitude and maritime effects. Bubble size represents extreme heat days.
Hardiness Zone Distribution
Number of counties in each USDA plant hardiness zone. Zones 6a through 8b cover the majority of US counties where lawns are commonly grown.
Longest Growing Seasons
The 10 counties with the longest frost-free periods. These are predominantly southern Florida, Hawaii, and coastal California counties.
Imperial County
CA
352 days
73.7°F avg
Alameda County
CA
349 days
59.9°F avg
Yuma County
AZ
344 days
74.1°F avg
Hidalgo County
TX
343 days
74.8°F avg
Contra Costa County
CA
341 days
60.4°F avg
Marin County
CA
339 days
59.4°F avg
Willacy County
TX
339 days
73.9°F avg
Zapata County
TX
337 days
74.4°F avg
Jefferson Parish
LA
333 days
69.7°F avg
Nueces County
TX
327 days
72.7°F avg