About Our Area
Average Frost Free Date:
Riverton May 21 - September 17 (119 Days)
Lander May 21 - September 15 (117 Days)
Dubois Jue 21 - August 26 (66 Days)
If you would like more information you can view the National Weather Service Website that lists the average last freeze and frost dates for our entire area. click here
USDA Hardiness Zones:
Riverton Wyoming and the surrounding areas have been re-classified by the USDA as the hardiness zone 5b, while Dubois is a USDA hardiness zone 4A. These zones are based on the minimum temperature a plant can survive. These USDA zones are not perfect for our area, plant health, and soil moisture also affect plant survivability. Reliable snow cover is the best insulator and can allow you to grow otherwise tender plants in very cold areas. Obviously this depends on Mother Nature.
Microclimates are small areas of your yard or neighborhood where the weather is different than what is generally happening. These areas may be colder, warmer, wetter or drier than the surrounding areas. Take advantage of these locations in your yard to grow plants that might not do well in other areas.
Problems & Solutions:
Problem: A relatively short growing season.
Solution: Grow lots of perennials and shrubs that tolerate light frosts. Also, put annuals out as transplants, to get a jump on the season. Utilize frost protection, for tender vegetable plants.
Problem: Winter sun and wind.
Solution: Give newly planted trees and shrubs a deep irrigation prior to the ground freezing. During dry, windy winters, water new plants when the temperature is above 40F.
Problem: Poor soils - most soils in our area are heavy clay that compacts easily. They are also alkaline with very low levels of organic matter.
Solution: Add soil pep, and Humic. Soil Pep loosens clay and helps improve drainage, Humic makes the soil less alkaline. Soil pep is also great for sandy soil as well. Whatever you do, don't add lime or wood ashes to alkaline soils as this makes the soil even more alkaline. Gypsum does not help our soils either. Gypsum contains calcium, which our soils already have high concentrations of.