Posts Tagged ‘usda plant hardiness zone map’
Before you plant the first seed in your flat or plan your garden, you will need to check the USDA Plant Hardiness Zone Map. This is a crucial step that many gardeners skip because they do not know how to use the map or do not understand the information on the map.
Past USDA Plant Hardiness Zone Maps have been divided into 10 categories. These categories were separated by 10 degrees. This 10-degree margin represents the average minimum winter temperature of an area. These margins are then divided into areas labeled “a and b.” These areas are separated by 5 degrees and add more climatic detail to a region.
As gardeners prepare for the upcoming gardening season, many will be viewing incoming seed catalogues along side their morning cup of coffee. Throughout the catalogue plant hardiness zones will be mentioned but do you really know the history behind these maps? This tale is full of intrigue, competition, and human nature.
The story begins among one of the darkest moments in United States history and that is the Great Depression. Two individuals working for two different agencies were honing in on an idea and that was a temperature map that could guide farmers in their plantings. Before this idea was conceived, plantings were guided by family traditions and The Farmers Almanac.
So during the 1930’s The U.S. National Arboretum was working on a map that would divide the United States into zones that were separated by 10 degrees Fahrenheit. At the same time, Arnold Arboretum was developing its own map. This map was divided into eight zones that could have a temperature difference of 5, 10, or 15 degrees.