Whether you want to plant shrubs or trees in your garden, the first thing to do is determine your hardiness zone. Hardiness zones (also known as growing or gardening zones) are a map developed by the USDA that divides North America into 13 zones based on the average low winter temperatures. Each zone is further broken down into two segments- “a and b”. These segments represent five-degree increments. The hardiness map is updated periodically.

How to use Hardiness Zone Information?

You can use hardiness zone information to find the average lowest winter temperature in your area and then pick the right plants for your location that have a high chance of surviving the winter. You can also use the Hardiness Zone map to compare the climate for your location with the ideal climate for a particular plant you want to grow in your backyard.

To simplify the process of choosing plants according to the hardiness zone, many nurseries provide detailed plant labels that display important information such as the lowest temperatures the plants can survive, whether they do better in sun or shade, and suitable hardiness zones.

You do not need to consider your hardiness zone when picking annuals for your garden as they usually survive only one season.

What the Hardiness Zone Map Doesn’t Tell You

The Hardiness Zone map does not talk about the following vital factors that gardeners should consider when choosing plants for their backyards.

Maximum temperature: The hardiness map does not indicate the average hottest summer temperature. This information is equally important when choosing plants for your garden. Research the species you’re considering to determine if it can survive in the summer.

Average first and last frost dates: The USDA Hardiness Zone map does not indicate when cold weather hits the zones. Gardeners should consider the last spring and first fall frost dates when determining the right time to plant tender annuals and vegetables. They can look the first and frost dates up by zip codes.

Humidity: Humidity levels can affect plant growth. The combination of winter chill and low humidity can affect plant health more than high humidity, as plants tend to lose less moisture when the relative humidity level is high. The USDA Hardiness Zone map does not provide any information about humidity.

Microclimate: The microclimate in your yard can be different from the surrounding area. In an urban setting, concrete and blacktop can provide protection from the cold in the winter. As a result, the temperature in your backyard might never reach the average lowest temperatures listed for your hardiness zone.

Sweetwater Landscapes is a leading landscape contractor serving Santa Rosa. Our pros have years of experience creating dreamy landscapes. To make an appointment with a qualified landscape designer, call (707) 887-0140.