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 ?