What Your Plant Hardiness Zone Won’t Tell You About Your Garden Climate

Although we can’t predict the weather, by learning more about past weather we can make a more educated guess about the future. By understanding your garden’s microclimate, you’ll be able to choose plants that will thrive in your particular neck of the woods.

Many gardeners rely on the USDA Plant Hardiness Zone Map for a quick and dirty way to decide what to plant based on their “zone”. Zones are also a favorite qualifier of some nurseries and seed companies. There are two main reasons I encourage you to look beyond your zone and more closely at your garden’s microclimate. For one, your zone–is based only on the “average annual extreme minimum temperature.’ For another–it is outdated. It’s developed from data from 1976 to 2005.

A map of Alaska indicating USDA Plant Hardiness Zones by color variation. Much of Northern and central Alaska consists of growing zones 1a to 2b, with coastal regions 2b to 4a and Southeast Alaska contains zones ranging from 4a to 7b.

Alaska USDA Plant Hardiness Zones.

I’m not going to tell you to set up a weather station in your back yard–although that would be the most accurate thing to do and there are some fairly inexpensive digital temperature monitors out there. I’m going to show you a couple of tools that will allow you to zoom in on the particular climactic conditions in your garden–all from the comfort of your armchair. Continue reading