Stephen Albert
Average frost dates–the last frost in spring and the first frost in autumn–can be used to set seed starting dates for the crops you plan to grow. They can also be used to set harvest dates and to plan the extension of the growing season–both early and late.
Most crops grow best during the frost-free days of the year. The days between the last frost in spring and the first frost in autumn make up the growing season. The growing season differs from region to region–longer in southern regions, shorter in northern regions.
The average date of the last and first frost allows you to estimate the length of your growing season. You can use the average date of the last and first frost to plan when seeds can be started in the garden when seeds should be started earlier indoors, and when seedlings started indoors can be set out in the open garden. Since most vegetables and herbs suffer when hit by frost, the average date of the last and first frost are very important.
Average dates of the last and first frost are estimates. They are based on historical averages, average dates kept by weather services, and state and federal agriculture agencies. These averages are commonly used as guidelines for planting and harvesting. Climate, weather, and growing season days can change from year to year so also averages can only be used to approximate when to plant or harvest.
Hardiness zones
In addition to last and first average frost dates, hardiness zones are helpful to gardeners.
A plant’s “hardiness” generally refers to its ability to survive winter temperatures. A plant that is considered hardy in Florida but cannot withstand winter low temperatures in Maine is not hardy to Maine. Hardiness zones were developed to help gardeners determine which plants can survive the minimum temperatures of a particular region.
Hardiness zones have been developed by the United States Department of Agriculture. There are 11 growing zones in the United States, zones 1-11. Zone 1 in Alaska has the coldest annual minimum temperatures (lows below -50°F) and Zone 11 in South Florida (lows above 40°F) is the warmest. Hardiness zones are further divided into “A” and “B”; “A” is the less warm region of the zone and “B” is the warmer region of the zone.
You can use last and first frost dates to help determine when the best time to plant a crop is. You can use hardiness zones to know how cold a place can get and which plants can survive there. There is an indirect correlation between the average frost dates and hardiness zones.
Other factors
Successful growing is also determined by the garden soil type, rainfall or irrigation, daytime temperature, nighttime temperature, day length, wind, humidity, and heat. Climates and growing conditions can vary even if they are in the same growing zone. Use the zones as a starting point, not as the final determinant of what will grow in your garden.
Here are average last frost dates, average first frost dates, average days in the growing season, and USDA zone for several cities in the United States, Canada, and other parts of the world.
United States
State and city Last frost First frost Grow days Zone
Alabama
Birmingham March 19 November 14 241 7B
Mobile February 17 December 12 298 8A
Montgomery February 27 December 3 279 8A
Alaska
Anchorage May 18 September 13 118 4
Barrow June 27 July 5 8 4
Cordova May 10 October 2 145 4
Fairbanks May 24 August 29 97 4
Arizona
Flagstaff June 8 October 2 116 5B
Phoenix January 27 December 11 317 9A
Tucson March 12 November 21 225 8A
Winslow April 28 October 21 176 5B
Arkansas
Fort Smith March 23 November 9 231 8B
Little Rock March 16 November 15 244 7A
Pine Bluff March 26 November 5 224 7B
Texarkana March 21 November 19 233 7B
California
Bakersfield February 14 November 28 287 8B
Eureka March 10 November 18 253 8B
Fresno February 3 December 3 303 8A
Los Angeles January 3 December 28 359 10
Marysville February 21 November 21 273 7B
Palm Springs January 8 December 18 334 9B
Pasadena February 3 December 13 313 9B
Red Bluff March 6 December 5 274 7B
Riverside March 6 November 26 265 8B
Sacramento January 24 December 11 321 8B
San Diego no frost no frost 365 10
San Francisco January 7 December 29 356 8B
San Jose February 10 January 6 299 8B
Santa Barbara January 22 December 19 331 8B
Santa Rosa April 10 November 3 207 8B
Colorado
Denver May 2 October 14 165 5A
Grand Junction April 20 October 9 173 6A
Pueblo April 28 October 12 167 5B
Connecticut
Bridgeport April 26 October 16 174 6A
Hartford April 22 October 19 180 5A
New Haven April 15 October 25 193 6A
Delaware
Dover April 17 October 22 188 7A
Newark April 20 October 17 180 7A
Wilmington April 18 October 26 191 7A
District of Columbia
Washington April 10 October 28 200 9A
Florida
Jacksonville February 6 December 16 313 8B
Miami irregular frost irregular frost 365 10
Orlando January 31 December 17 319 9B
Tallahassee February 26 December 3 280 8B
Tampa January 10 December 26 349 9A
Georgia
Atlanta March 20 November 19 244 7B
Augusta March 14 November 1 249 7B
Macon March 12 November 19 252 7B
Savannah February 21 December 9 291 8B
Hawaii
Hilo no frost no frost 365 10 `
Honolulu no frost no frost 365 10
Idaho
Boise April 29 October 16 171 6A
Coeur d’Alene May 12 October 14 155 5B
Pocatello May 8 September 20 155 4
Illinois
Cairo March 23 November 11 233 6A
Chicago April 19 October 28 192 5B
Rockford May 7 October 11 157 5A
Springfield April 8 October 30 205 5B
Urbana April 22 October 20 151 5B
Indiana
Evansville April 2 November 4 216 6A
Fort Wayne April 24 October 20 179 5B
Indianapolis April 17 October 27 193 5B
Iowa
Des Moines April 20 October 19 183 5A
Dubuque April 19 October 19 184 5A
Mason City April 25 September 25 153 4
Sioux City April 27 October 13 169 4
Kansas
Concordia April 16 October 24 191 5B
Topeka April 9 October 26 200 5B
Wichita April 5 November 11 210 6A
Kentucky
Lexington April 13 October 28 198 6A
Louisville April 1 November 7 220 6B
Louisiana
Lake Charles February 18 December 6 291 8B
New Orleans February 13 December 12 302 9A
Shreveport March 1 November 27 272 8A
Maine
Bangor May 1 October 4 156 5A
Caribou May 19 September 21 125 4
Greenville May 27 September 20 116 5A
Portland April 29 October 15 169 5A
Presque Isle May 31 September 18 110 4
Maryland
Baltimore March 28 November 17 234 7A
Cumberland May 1 October 10 163 6A
Salisbury April 20 October 20 183 7A
Massachusetts
Amherst May 12 September 19 130 5B
Boston April 16 October 25 192 6A
Fall River April 22 October 23 184 6A
Nantucket April 12 November 16 219 6A
Pittsfield May 12 September 27 138 5B
Worcester May 7 October 2 148 5B
Michigan
Detroit April 25 October 23 181 5B
Escanaba May 14 October 6 145 4
Grand Rapids April 25 October 30 190 5B
Lansing May 6 October 8 155 5B
Marquette May 13 October 19 159 4
Minnesota
Albert Lea May 3 October 6 156 4
Duluth May 22 September 24 125 3
Minneapolis April 30 October 13 166 4
Virginia May 29 September 14 108 3
Mississippi
Biloxi February 22 November 28 279 8B
Jackson March 10 November 13 248 7B
Tupelo March 31 October 28 211 7B
Vicksburg March 8 November 15 252 7B
Missouri
Columbia April 9 October 24 198 5B
Kansas City April 5 October 31 210 5B
Saint Joseph April 11 October 14 186 5B
St. Louis April 2 November 8 220 5B
Springfield April 13 October 20 190 6A
Montana
Billings May 15 September 24 132 4
Glasgow May 19 September 20 124 3
Great Falls May 9 September 25 139 4
Havre May 9 September 23 138 4
Nebraska
Lincoln April 20 October 17 180 5A
Norfolk May 4 October 3 152 5A
North Platte April 30 October 7 160 5A
Omaha April 14 October 20 189 5A
Nevada
Elko June 6 September 3 89 5A
Las Vegas March 13 November 13 245 7A
Reno May 14 October 2 141 5B
New Hampshire
Berlin May 29 September 15 109 4
Concord May 11 October 1 143 5A
Errol June 1 September 5 96 4
New Jersey
Atlantic City March 31 November 11 225 6B
Cape May April 4 November 13 222 6B
New Brunswick April 21 October 19 179 6A
Newark April 3 November 8 219 6A
Trenton April 8 November 5 211 6B
New Mexico
Albuquerque April 16 October 29 196 7A
Roswell April 9 November 2 208 7A
Santa Fe April 23 October 19 179 5A
New York
Albany April 27 October 13 169 5A
Binghamton May 4 October 6 154 5A
Buffalo April 29 October 23 178 5B
New York City April 7 November 12 219 6B
Syracuse April 30 October 15 168 5A
Watertown May 7 October 4 151 5A
North Carolina
Asheville April 12 October 24 195 7A
Charlotte March 21 November 15 239 7B
Raleigh March 24 November 16 237 7B
Wilmington March 15 November 19 274 7B
Winston Salem April 14 October 24 193 7A
North Dakota
Bismarck May 11 September 24 136 4
Fargo May 13 September 27 137 4
Williston May 14 September 23 132 3
Ohio
Cincinnati April 15 October 25 192 6A
Cleveland April 21 November 2 195 5B
Columbus April 17 October 30 196 5B
Dayton April 20 October 21 184 5B
Toledo April 24 October 25 184 5B
Oklahoma
Miami April 7 October 26 202 6A
Oklahoma City March 28 November 7 223 7A
Tulsa March 31 November 2 216 6B
Oregon
Bend June 8 September 7 91 5B
Eugene April 13 November 4 205 7B
Medford April 25 October 20 178 7B
Portland February 25 December 1 279 8A
Salem April 14 October 27 197 7B
Pennsylvania
Altoona May 6 October 4 151 5B
Erie May 1 October 11 163 5A
Harrisburg April 10 October 28 201 6A
Philadelphia March 30 November 17 232 6B
Pittsburgh April 20 October 23 187 6A
Scranton April 24 October 14 174 5B
Williamsport May 3 October 13 164 5B
Rhode Island
Kingston May 1 October 14 166 6A
Providence April 13 October 27 197 6A
South Carolina
Charleston February 19 December 10 294 8A
Columbia March 14 November 21 252 7B
Greenville March 23 November 17 239 7B
South Dakota
Huron May 4 September 30 149 5A
Rapid City May 7 October 4 150 5A
Sioux Falls May 5 October 3 152 5A
Tennessee
Chattanooga March 26 November 11 229 7A
Knoxville March 31 November 6 220 6B
Memphis March 20 November 12 237 7A
Nashville March 28 November 7 224 6B
Texas
Brownsville February 15 December 10 298 9A
Corpus Christi January 26 December 27 335 9A
Dallas March 18 November 22 249 8A
El Paso March 26 November 14 238 8B
Houston February 5 December 11 309 8B
Lubbock April 1 November 9 205 7A
Plainview April 10 November 6 211 7B
Utah
Blanding May 18 October 14 148 6B
Logan May 15 October 6 144 6B
Ogden April 13 October 22 192 6B
Salt Lake City April 12 November 1 202 6B
Vermont
Bennington May 15 October 4 142 5A
Burlington May 8 October 3 148 4
St. Johnsbury May 22 September 25 126 3
Virginia
Norfolk March 18 November 27 254 7B
Richmond April 2 November 8 220 7A
Roanoke April 20 October 24 187 7A
Washington
Centralia April 27 October 7 173 7B
Seattle February 23 December 1 281 7B
Spokane April 20 October 12 175 5B
Walla Walla April 3 November 1 211 5B
Yakima April 15 October 22 190 6A
West Virginia
Charleston April 18 October 28 193 6B
Martinsburg April 29 October 16 170 6B
Parkersburg April 16 October 21 189 6A
Wisconsin
Green Bay May 6 October 13 161 5A
Lacrosse May 1 October 8 161 4
Madison April 26 October 19 177 5A
Milwaukee April 20 October 25 188 5B
Wyoming
Casper May 18 September 25 130 4
Cheyenne May 20 September 27 130 4
Sheridan May 21 September 21 123 4
Puerto Rico
All locations no frost no frost 365 10
Virgin Islands
All locations no frost no frost 365 10
Canada
Alberta
Calgary May 28 September 9 104 3
Edmonton May 14 September 14 123 3
British Columbia
Prince George June 10 August 28 79 3
Victoria February 28 December 9 284 7B
Manitoba
Churchill June 26 September 12 82 2
Winnipeg May 25 September 21 119 3
New Brunswick
Fredericton May 18 September 26 130 4
Newfoundland
Saint John’s June 3 October 12 131 5A
Northwest Territories
Yellow Knife May 30 September 16 109 2
Nova Scotia
Halifax May 15 October 15 153 5B
Ontario
Toronto April 20 October 30 193 5B
Prince Edward Island
Charlottetown May 17 October 15 151 5A
Quebec
Montreal May 3 October 17 155 4
Quebec City May 18 September 18 123 4
Saskatchewan
Regina May 27 September 12 108 5B
Yukon
Dawson May 26 August 27 93 4
Growing Zones throughout the World
Country and city Zone Minimum
Argentina
Buenos Aires 9
Cordoba 9
Australia
Adelaide 10 Australia zone 4
Brisbane 10 Australia zone 4
Melbourne 10 Australia zone 4
Perth 10 Australia zone 4
Sydney 10 Australia zone 4
Austria
Vienna 6
Belgium
Brussels 8
Chile
Santiago 10
China
Beijing 7
Hong Kong 10
Shanghai 9
France
Lyon 8
Paris 8
Marseille 9
Germany
Berlin 6
Frankfurt 7
Hamburg 7
Munich 6
Ireland
Belfast 9
Dublin 8
Galway 9
Italy
Florence 9
Milan 8
Palermo 10
Rome 9
Venice 8
Japan
Sapporo 6
Kyoto 9
Tokyo 9
New Zealand
Auckland 10
Christchurch 9
Wellington 10
South Africa
Cape Town 11
Durban 11
Johannesburg 9
Spain
Barcelona 10
Cordoba 9
Madrid 9
Seville 10
Valencia 10
United Kingdom
Bristol 9
Glasgow 8
Inverness 8
Leeds 8
Liverpool 9
London 8
Uruguay
Montevideo 10
