According to the United States Department of Agriculture (USDA) hardiness zone map, the United States is split up into 11 different hardiness zones. Plant hardiness zones act as a guideline for gardeners so that they can estimate when to plant vegetables, fruits and plants according to their germination and blooming times. Depending on climate and environmental factors, some plants will thrive only in specific areas and not succeed in others.
Zones 1 and 2
The minimum temperatures in zone 1 are minus 50 degrees Fahrenheit. In the early spring season, once the soil can be worked through, begin to sow seed. Resolute and northwest territories of Canada make up the area of zone 1. The areas of Flin Flon and Manitoba, Canada, create zone 2. Minimum temperatures range anywhere from minus 45 to minus 50 degrees F. Seed should be sown in the early spring. Zone 2b is the area of Pinecreek, Minnesota, and Unalakleet, Alaska. The temperature range is from minus 40 to minus 45 F. Seed should be sown early in the spring once the soil is able to be worked through.
Zones 3 and 4
Zone 3a is located in the International Falls area of Minnesota. The season of spring is through the months of April 15 and June 15. The fall season is during the months of August 15 and October 1. In zone 4, the spring season is during the months of April 15 and June 15. Fall takes place in the months of September 1 and October 15. Zone 4a is in the area of Minneapolis and St. Paul, Minnesota, while zone 4b is located in Northwood, Iowa. The minimum temperatures in zone 4 range anywhere from minus 20 to minus 30 F.
Zones 5 and 6
In zone 5, the minimum temperatures average between minus 10 to minus 20 F. The spring season is during the months of April 15 and June 15. The fall season is September 1 through October 15. Areas found in zone 5a include Des Moines, Iowa. The area that is a part of 5 includes Columbia, Missouri. The months of March 15 through May 15 in zone 6 is the season of spring. Temperatures fall in the minimum range of minus 10 to 0 degrees F. September 15 through November 1 is the season of fall. Areas included in zone 6 are St. Louis, Missouri (zone 6a), and Branson, Missouri (zone 6b).
Zones 7 and 8
The minimum temperatures of zone 7 average from zero to 10 degrees F. Spring occurs during the months of February 15 through April 15. September 15 through November 15 is the season of fall. Areas included in zone 7 are Oklahoma City, Oklahoma (7a), and Little Rock, Arkansas (7b). In zone 8, the average minimum temperatures are 10 to 20 F. The season of spring is through the month of January 15 until March 1. Fall is October 1 through December 1. Some of the areas that make up zone 8 include Dallas, Texas (8a), and Austin, Texas (8b).
Zones 9, 10 and 11
Zones 9, 10, and 11 all have the seasons of spring during the months of January 1 through March 1. The season of fall during these three zones are October 1 through December 1. In zone 11, the average minimum temperature is 40 F. The minimum temperatures in zones 9 and 10 range anywhere from 20 to 40 F. Zone 10 includes the cities of Naples and Miami in the state of Florida. The state of Texas creates zone 9. Mazatlan, Mexico, is included in zone 11.