Home » Plants & Animals » Gardening in Southern U.S. » A Zone by Any Other Name...

A Zone by Any Other Name...

© Emily Levitt

I've found that gardening is more of a vast experimental puzzle than an exact science, as some pundits would have you (and me ) believe. There are some given elements- water and sun are required for all growing things- and, for years, I followed the USDA Zone map as a guide when selecting plant material.

It dawned on many of us who live the diverse areas of our country that this map, however well-intended, assumes that all of us live in climates which resemble Great Britain, or New England . The fact is that heat and humidity have a great impact on garden plants in most of the United States.The Zone 7 in which I live has at least 90 days of temperatures above 86 degrees, while that "same" Zone 7 in Maryland may have as few as fifty hot days. Add to this the quality of evening temperatures and humidity and you have two very different environments, yet you will find information on many specimens listed merely by Zone hardiness (cold-resistance.)

Enter the American Horticulural Society and its' Heat-Zone Map. http://www.suite101.com/userfiles/79/hz1...

***Editors' Update 2/25/99***

The Atlanta Journal printed this map in color on the cover of their Garden section, so have at it on the URL listed here!

This is one of the best ideas to aid plant selection to come down the pike in a long time. The system of heat days is determined by the average number of those days with a temperature of 86 degrees of higher in a given USDA Zone. Combining this information with hardiness, and you get a much better total picture of your gardening environment.

The AHS Encyclopedia of Plants, available in almost every library in the country, is also a good source of heat /humidity tolerance for general use. I broke down and bought a copy a couple of years ago and have used it extensively. I have used it side-by-side with Perennials For American Gardens, a great resource book as well.

Consider all the elements of your area when selecting plants, to increase the chance success of a given specimen. And remember, there's a plant out there to make a liar out of all of us at least once.