The chart published by the USDA and complete interactive searching can be found on the website for the US National Arboretum. When researching your location, bear in mind that the map lines are not absolute and each garden has it's own unique micro-climate. Neighborhoods with more trees blocking the wind, hills that "drain" away moisture faster, concrete bulkheads, sidewalks and driveways that tend to collect heat, as well as southern exposures will allow you to grow plants that might not be recommended for your area. The general guidelines are based on average low temperature are found below.
To open a new browser window access the interactive map click USDA Zone ChartAsiatics (Graffity, Tigerplay, etc.) grow best in zones 1 to 9, no winter mulch is needed and they prefer colder winters to reset bloom.
Purebred Orientals (Casablanca, Star Gazer, etc.), without mulch, zones 6 to 9, but if heavily mulched for winter or with a good snowfall, down to zone 3 or 4 easily.
Purebred Trumpets (Copper King, Pink Perfection, etc.), without mulch, zones 7 to 10; heavily mulched, down to zone 3 or 4, but can be subject to late freeze damage in May, cover emerging stems if temperatures below 30 degrees F. are expected.
Oriental-Trumpet Hybrids (Conca ‘dOr, Sweetheart, etc.), same as Purebred Orientals, but seem to be more resistant to late frost damage, plus because of the “trumpet” genes, they do not require as much winter chill as Oriental lilies, thus are very suitable for southern areas and will take higher heat in summer. (See our
Heatbuster™ Collection for more information.)
Zone 1 --- ( Below -50 F) --- Fairbanks, Alaska; Resolute, NW Territories (Canada)
Zone 2a --- (-50 to -45 F) --- Prudhoe Bay, Alaska; Flin Flon, Manitoba (Canada)
Zone 2b --- (-45 to -40 F) --- Unalakleet, Alaska; Pinecreek, Minnesota
Zone 3a --- (-40 to -35 F) --- International Falls, Minnesota; St. Michael, Alaska
Zone 3b --- (-35 to -30 F) --- Tomahawk, Wisconsin; Sidney, Montana
Zone 4a --- (-30 to -25 F) --- Minneapolis/St.Paul, Minnesota; Lewistown, Montana
Zone 4b --- (-25 to -20 F) --- Northwood, Iowa; Nebraska
Zone 5a --- (-20 to -15 F) --- Des Moines, Iowa; Illinois
Zone 5b --- (-15 to -10 F) --- Columbia, Missouri; Mansfield, Pennsylvania
Zone 6a --- (-10 to -5 F) --- St. Louis, Missouri; Lebanon, Pennsylvania
Zone 6b --- (-5 to 0 F) --- McMinnville, Tennessee; Branson, Missouri
Zone 7a --- (0 to 5 F) --- Oklahoma City, Oklahoma; South Boston, Virginia
Zone 7b --- (5 to 10 F) --- Little Rock, Arkansas; Griffin, Georgia
Zone 8a --- (10 to 15 F) --- Tifton, Georgia; Dallas, Texas
Zone 8b --- (15 to 20 F) --- Austin, Texas; Gainesville, Florida
Zone 9a --- (20 to 25 F) --- Houston, Texas; St. Augustine, Florida
Zone 9b --- (25 to 30 F) --- Brownsville, Texas; Fort Pierce, Florida
Zone 10a --- (30 to 35 F) --- Naples, Florida; Victorville, California
Zone 10b --- (35 to 40 F) --- Miami, Florida; Coral Gables, Florida
Zone 11 (above 40 F) Honolulu, Hawaii; Mazatlan, Mexico