On Nov. 15, the United States Department of Agriculture (USDA) published an update of a standard gardening tool, its “Plant Hardiness Zone Map.” This map is the most popular guide about whether a particular type of plant will or won’t survive in your garden.
You’ll find the USDA map in most gardening books and referred to on most plant labels at your local garden center, and in plant descriptions in nursery catalogs.
Interesting Changes
Changes from the 2012 edition provide unmistakable evidence that the climate throughout most of the United States is changing. Winter cold is the primary challenge to a plant’s survivability. However, many other factors also determine whether a perennial plant, tree or shrub is going to survive from one year to the next. They are heat, draught, and additional factors in the Northeast such as warmer winters with less snowfall, can prove more challenging for cold sensitive plants. With climate change, less reliable precipitation in the Northeast — with weather tending to veer from drought to flood – and greater summer heat which are challenges.
Labels
Labels will indicate the zone recommended. The region of southwestern Massachusetts has been assigned to zone 6a.
Advice to the Gardener
Read the map, in other words, but with a grain of salt, adjusting for climate change.
Be-a-Better-Gardener is a community service of Berkshire Botanical Garden, located in Stockbridge, Mass. Its mission, to provide knowledge of gardening and the environment through a diverse range of classes and programs, informs and inspires thousands of students and visitors each year. Thomas Christopher is a volunteer at Berkshire Botanical Garden and is the author or co-author of more than a dozen books, including Nature into Art and The Gardens of Wave Hill (Timber Press, 2019). He is the 2021 Garden Club of America’s National Medalist for Literature, a distinction reserved to recognize those who have left a profound and lasting impact on issues that are most important to the GCA. Christopher’s companion broadcast to this column, Growing Greener, streams on WESUFM.org, Pacifica Radio and NPR and is available at berkshirebotanical.org/growinggreener.
