What zone is your landscape in? If you knew that, you might get a better understanding of what can grow in your yard.

You can figure out your landscape profile by using a number of plant-hardiness maps available to gardeners.

In January, the U.S. Department of Agriculture released an updated Plant Hardiness Zone Map that tells growers how cold it gets in their neighborhoods.

Some of the zones were adjusted to reflect new data that cover a 30-year period instead of a 13-year period.

Its online version also provides zone information that targets neighborhoods instead of larger regions.

While the map helps you figure out which plants might survive our winter, it's far from accurately depicting local growing conditions, maintains a gardening expert.

"If you look at the USDA map, we're in the same zone as some of coastal or Northern California," says Peter Warren, county extension director of Pima County Cooperative Extension.

"While we may have similar winter temperatures, there they don't get nearly as hot as we do and get way more rain than we do."

The cooperative extension, including its volunteer educators known as master gardeners, prefers to use the map in the Sunset Western Garden Book.

That map factors in other influences such as rainfall, humidity and geography.

Additionally, "Sunset has much more detailed maps of the western United States and Arizona," Warren says.

Local gardeners can check out at least two other zone maps.

The American Horticultural Society (AHS) Heat Zone Map provides the annual average number of days in which the temperature is at least 86 degrees.

The cooperative extension's Arizona Plant Climate Zones Map describes plants that can grow in an area's expected minimum temperatures.

Even with this information, you'll still have to deal with specific issues such as microclimates and your watering habits.

But, says Warren, the maps give you "a starting point" for buying plants that could survive in your landscape.

What the zones mean for gardeners

Neighborhoods around the University of Arizona are typical of much of Tucson. They are in the USDA's Zone 9b, Sunset's Zone 12, AHS' Zone 8 and Arizona's Zone 4.

Together, that means gardeners should grow plants that survive in temperatures as low as 25 degrees. The neighborhoods experience 90 to 120 days of 86-plus degrees in a year. The area has a few hard frosts over a long cold season.

Subtropicals can do well only if protected in the winter. On the other hand, it doesn't get cold enough to successfully grow many deciduous fruit trees.

Cool-season plants will become well-established for summer heat if set between September and November. Cold-tender plants may experience frost damage if planted in the fall.


Each of these interactive maps uses your ZIP code to identify your zone.

• American Horticultural Society, www.ahs.org/publications/heat_zone_map.htm#1

• "Sunset Western Garden Book," www.sunset.com/garden/climate-zones

• U.S. Department of Agriculture, planthardiness.ars.usda.gov/PHZMWeb

• The Arizona Plant Climate Zone, cals.arizona.edu/pubs/garden/az1169, uses points of reference to identify its zones. Tucson is one of those reference points in Zone 4.

Contact local freelance writer Elena Acoba at acoba@dakotacom.net