Increasingly severe storms, rising temperatures, too much or too little precipitation and an uptick in the number of wildfires are among the challenges growers face across the U.S. as the climate begins to change, reports the U.S. Department of Agriculture. As the climate shifts, Western North Carolina gardeners and farmers may need to explore new plant choices and growing strategies.
“We are in the unfortunate situation of being the first generation of gardeners ever who cannot rely on historical weather records to tell us what our climate is or what to expect in the future,” writes Cornell University horticulture professor David Wolfe in The New American Landscape: Leading Voices on the Future of Sustainable Gardening. While in cooler climates that may mean longer growing seasons, he says, it can also mean that “we are entering an era of great uncertainty that makes gardening even more challenging than it was before.”
In January, the Asheville-based National Centers for Environmental Information reported that the past three years were the hottest ever recorded in America, and 2016 and 2017 were record hot years for Asheville. The area had an overall average temperature of 58.4 degrees, which is 2.6 degrees above normal, according to NCEI.
The National Oceanic and Atmospheric Administration reports that this May was not only above average in temperature for 34 states in the U.S. but also saw record rainfall in the Mid-Atlantic states and throughout the Southeast, which led to mudslides and flooding, including in Asheville. Across the country, other states saw anomalies — 100 degrees Fahrenheit in Minnesota on May 28, the earliest ever recorded; the Northwest saw record melting of snow pack; and Alaska saw its fourth-wettest May on record. The average temperature across the country was 65.4 degrees Fahrenheit, 5.2 degrees above average and the warmest May on record, while the average precipitation across the U.S. in May was 2.97 inches, 0.06 inches above average.
But Chris Hennon, chair of the atmospheric sciences department at UNC Asheville, says WNC’s climate has not yet experienced a dramatic shift. “Although temperatures have recently increased, the total is less than 1 degree Fahrenheit since 1900,” he says, citing data from the North Carolina climate summary published by NCEI. “There have been no detectable trends in annual precipitation or heavy precipitation events — days that receive 3 or more inches of rain. So, in my opinion, historical averages for gardeners are still useful guides.”
In the future, gardeners in WNC can expect a longer warm season, says Hennon, along with overall increases in precipitation in winter and spring accompanied by increases in drought conditions. “The warmer temperatures that are expected will lead to higher soil-moisture loss, so more care will have to be made to keep plants hydrated,” he explains. And those changes will come quickly — in decades rather than over centuries or millennia. With those weather changes, drought-resistant species and tropical plants should do well, he says, while cool-weather plants will have a shorter lifespan.
Laura Carter, manager at Thyme in a Garden in Asheville, suggests that gardeners may want to do some investigating on their own plus get involved with local gardening groups to brainstorm solutions to the impending challenges. “As gardeners, we’re constantly learning by experience. We have to be prepared and do our research in order to find the best plants for the coming gardens,” she says. “Working and volunteering in the Asheville gardening community is where you’re going to find the right stuff on the cutting edge of species today.”
Although he agrees that weather conditions are in flux, Steve Pettis, an extension agent with the Henderson County Extension Office, doesn’t see any reason to panic. The climate, he says, has been changing for centuries. “The extension service has been in business since 1914, and we’ve seen the weather patterns change many, many times,” he says. “Sixty years ago, in Hendersonville, you could see the tops of the buildings — there were no trees. The climate there has definitely been changed by reforestation and differing land use.”
In those days, land was used primarily for agriculture, which meant fewer trees, resulting in more reflected heat, warmer temperatures and lower rainfall due to less condensation rising into the atmosphere. Reforestation efforts have led to a lusher landscape, he says, but the area’s population growth is causing increased flooding and higher temperatures due to larger numbers of structures and paved areas.
“One of the things we’re doing a lot now is educating homeowners and farmers about reducing stormwater runoff,” he says. Pettis recommends that gardeners install rain gardens (ponds that fill when it rains and slowly release water into the ground) and rainwater collection systems to help prevent flooding.
With higher temperatures, there is also a greater likelihood of less rain. And the best way to pre-emptively address potential drought conditions and problem landscapes is to embrace native species. “We have too many beautiful native plants to replace them with plants from outside the area that may not grow as well or may become invasive,” he says.
Some plants, such as miscanthus grass, may work beautifully in areas of Georgia, for example, but become invasive when they are transplanted to the mountains. Others, such as English ivy and Japanese honeysuckle, may be easily contained in other areas of the country but spread like wildfire in the mountains, Pettis says.
With WNC being one of the best growing areas in the world, he says, native plants will thrive here if they don’t have to compete with nonnative interlopers. “As the climate changes and the winters get milder, those invasive species will just thrive and push the native species out even more,” he says.
Pettis recommends that gardeners interested in using native plants in their landscapes and avoiding invasive species consult the North Carolina Native Plant Society at ncwildflower.org.