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Frost-Free Dates

Source: USDA, "Growing Vegetables in the home," 1972, North Dakota State Univ. Extension Service. The National Arbor Day Foundation allows visitors to search by zip code for their Hardiness Zone . The maps below indicate the changes in drought and hardiness zones. Planter 's location in central NH has changed from Zone 4-5 to Zone 5 in the seven years since our retirement.  Zone 8  seems to be winning the heat index creep and Zones 3 and 4 are losing the battle to stay cool.   More proof that desertification and glacial meltdown are not going away.

Zone      Temperature range (F)    Frost-Free Date
1         below -50           ?
2         -50 to -40         June 10
3         -40 to -30         May 30
4         -30 to -20         May 20
5         -20 to -10         May 10
6         -10 to 0           Apr 30
7         0 to 10            Apr 20
8         10 to 20           Apr 10
9         20 to 30            ?
10        30 to 40            ?  
            

zone_hardinesschange.jpg (53474 bytes)