Knowing the hardiness zone where you live is an important factor to take into consideration when making plant choices. Plant hardiness zones determine what plants are suitable for planting in a particular area based on the the location's mean low temperature during the winter. Plants that are able to withstand the low temperatures in that area are deemed appropriate for that zone. It is recommended that you don't base your plant choices entirely on the zone as it does not take into consideration average highs during the summer which also plays a role in determining what plants will grow in your particular area. For example, wet areas in Washington State are in the same zone as arid areas found in the Southwest. Obviously, a cactus won't survive outside in Washington, just as a fern wouldn't survive in the desert. With that said being familiar with your zone and the average low temperature will help to guide you to choose a plant that can withstand the winters in your area.

An even easier way to know that your plant choice will survive is to choose native plants. Natives have been growing in your area for hundreds of years, withstanding the weather and the elements, providing proof of their success.

• In Washington State, the Washington Native Plant Society maintains plant lists for every county. Refer to this resource when making your next plant choice to ensure your decision has withstood the hardest test of all, the test of time.
  

USDA PLANT HARDINESS ZONE MAP FOR THE UNITED STATES AND CANADA

Image by USDA

USDA PLANT HARDINESS ZONE MAP FOR THE PACIFIC NORTHWEST