Know Your Zone

Last Updated on Wednesday, 23 February 2011 22:56 Written by Corrina Wednesday, 23 February 2011 21:10

Probably the most basic factor in selecting the right plants for your landscape depends on the region in which you live. The USDA divides the United States and southern Canada into 11 regions, or Plant Hardiness Zones.  These zones are defined by an area’s average low temperature and are separated by a difference of 10 degrees Fahrenheit.  Zone 1 is the coldest region with an average low temperature of   -50 degrees Fahrenheit and zone 11 is the warmest region with an average low temperature of +40 degrees Fahrenheit. These zones can be further divided into “a” and “b” with a difference of 5 degrees Fahrenheit.

The USDA Hardiness Zones are divided according to average low temperatures since they represent the minimum temperatures a plant variety can withstand to survive.  For example, one of the Southern Living Plant Collection’s most popular shrub varieties is the Purple Pixie Weeping Loropetalum and it thrives in zones 7 – 10.  This means that it is most hardy in temperatures that do not drop below 0 degrees Fahrenheit.  Though the USDA Hardiness Zones provide reasonable guidelines when selecting plants for your area, it’s good to remember that they are only guidelines – there are always exceptions and other factors to consider if you really want to grow a plant variety just outside your zone.

Most likely a plant that is hardy in zone 8 – 10 will not survive a zone 6 winter since there is a 20 degree average low difference, but you may find success growing a zone 8 – 10 plant in zone 7 or a zone 7 plant in zone 6.  If you’re growing a plant variety in a slightly colder region than recommended (or even if your region is experiencing colder than usual temperatures) plan to use extra winter protection by adjusting the watering schedule, spreading additional mulch, and covering the plant with breathable material.  See “Cold Tips for the Southern Living Plant Collection” for more information. You can also grow plants in containers and bring them indoors for winter. This will ensure plant survival as well as bring life into your home.  Finally, a perfect solution for growing plant varieties outside your zone is identifying and/or creating microclimates. To learn more about microclimates, see “What is a Microclimate?.”

From the Southern Living Plant Collection website, click on Find Your USDA Growing Zone and either click on your state on the map or enter your city, state, and/or zip code in the search box and click “Find!”

Here are some of the Southern Living Plant Collection favorites ranging from USDA Hardiness Zones 4b – 11.

Trees, Shrubs, and Grass:

Mountain Snow Pieris zones 4b – 9 (average winter from -25 to 30 F)

Marc Antony Liriope zones 5 – 9 (average winter from -20 to 30 F)

Flirt Nandina zones 6 – 10 (average winter from -10 to 40 F)

Purple Diamond Compact Purple Loropetalum zones 7 – 10 (average winter from 0 – 40 F)

Early Bird and Delta Jazz Crapemytles zones 7 – 10 (average winter from 0 to 40 F)

Perennials and Bulbs:

Tinka Tulip fall blooming bulbs in zones 5 – 9 (average winter from -20 to 30)

Red Spider Lily fall blooming bulbs in zones  6 – 10 (average winter from -10 to 40 F)

Habranthus Pink Rain Lily spring bulbs in zones  6 – 11 (average winter from -10 to above 40 F)

Ellen Bosanquet Crinum spring bulbs in zones  7 – 10 (average winter from 0 – 40 F)

Plum Mist Cuphea perennials in zones 7 – 11 (average winter from 0 to above 40 F)

Golden Dawn Narcissus fall blooming bulbs in 7 – 11 (average winter from 0 to above 40 F)

Ragin Cajun Ruellia perennials in zones 7b – 11 (average winter from 5 – to above 40 F)

*Annuals:

Cajun Blue Scaevola zones 9 – 11 (average winter from 30 to above 40 F)

Vivian Vogue Mandevilla zones 9 – 11 (average winter from 30 to above 40 F)

*When grown under the right conditions, annuals can return year after year as perennials.  For example, if you are growing Vivian Vogue Mandevilla in zones 9 – 11, there is a good possibility the plant will return in summer as long as the temperature doesn’t go below 30 degrees in winter. Test it out by planting one of our Mandevillas in a container and bringing it indoors for winter.  Place the container near a light source, e.g., a window or lamp, but make sure it doesn’t get chilly!