Garden Landscaping Planning with The Zone System

Using the Zone system is the key to creating the best garden possible.

This system divides the country into eleven zones, and was started by the USDA (United States Dept. of Agriculture). Average winter temperature is the factor that separates one zone from another, with 11 being the warmest and 1 the coldest. You can easily find maps defining each zone online to help you figure out which zone you are in.

Another well known system is called the Sunset Western Climate zone system, and was designed by Sunset, which is a popular gardening publication company. This system divides the western portion of North America into 24 zones. It also makes provisions for Hawaii (H1-H3) and Alaska (A1-A3).

The Zones are:
Cold and Snowy: 1-3
Rainy Northwest Zones:4-6
Northern and Interior-alley California Zones: 7-9, 14-17
Southern California: 18-24
Southwest Desert Zones: 10-13

The Sunset system is more involved than the USDA version, and takes into consideration summer temperatures, annual rainfall, elevation and humidity. It also factors in things like marine and mountain geography. This system also considers the number of days between the beginning of Spring and the first frost. This length of time is the average growing season for each zone.

If you want to narrow it down even further, many of the zones can be broken down into what’s known as micro-climates. For example, Northern Idaho has a panhandle that is shielded from much of the Winter weather by the nearby mountains. Montana, which is on the other side, experiences much harsher Winters.

Just as they sometimes keep certain weather out, mountain ranges can also funnel cold or warm air into a region that normally wouldn’t get it. An example of this is the wine growing region of Southern California. Many of the vineyards are located in a narrow valley that traps the hot air. These valleys also channel cold breezes in from the Pacific Ocean during the evenings. These influences combine to create an ideal grape-growing environment.

These micro-climates are capable of supporting plant life that normally would not do well in that particular zone. This does not always hold true, however. For example, lemon trees are still going to thrive in Southern California as opposed to Eastern Washington.

The Zone System is a good starting point for selecting the proper trees and plants for your area. However, you can still experiment to see if there are other options available to you as well. If you live in a Zone 2, you certainly would not want to waste your time and money planting something that is rated up to zone 5.

Certain characteristics of plants, such as hardiness are mostly genetic. This means that if a plant is not rated for the zone you live in, you should probably avoid it, because there is little you can do to adjust these characteristics. Take some time to research your particular zone and use the plants that are recommended. This will save you a lot of work and money down the road.

         

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