Illustration by Phong Nguyen
When mankind opened the Pandora’s box of petrochemicals a century and a half ago, it fueled a future of meteorological change — drought, storm surges and bomb cyclones. Central Virginia has been spared those mercurial shifts. We’re simply having more extremes of the same weather we’ve always had. It’s hotter here for longer. Our rain events are rainier. In Richmond, climate change is a matter of degree.
In 1960, when the USDA first issued its map of hardiness zones, Richmond was located in zone 7. Climate change has nudged the boundaries of zone 8 northward, forcing gardeners in Central Virginia to rethink what to plant, when to plant and where to plant it. “Changes in climate mean changes in growing conditions,” says Dean Dietrich, a horticulturalist at Lewis Ginter Botanical Garden.
A year in Richmond that was once divided into four distinct seasons with moderate temperature shifts has morphed into what Dietrich describes as an “extended summer that drops off into winter without a nice cool-down period like fall used to be.” According to Jeremy Hoffman, climate and earth scientist at the Science Museum of Virginia, the final frost that local gardeners once celebrated in mid-April is now arriving in late March; autumn’s first frost has been postponed from late October until early November. “Earlier onsets of springtime temperatures leave flowers, fruits and vegetables vulnerable to late-season frost,” he warns. “Longer, more intense summers increase the danger of unpredictable harvests during the height of the hurricane season.”
Last year was the second wettest year on record in our region. “The largest increases in seasonal rainfall have occurred during the fall, while the largest decreases have occurred in the summer,” Hoffman reports. “Climate models indicate that these sorts of patterns will only continue to get more pronounced.” We’re learning to expect the unexpected.
The extended summer heat and humidity that is threatening our native plants is breeding disease and offering up an “environment hospitable to exotic invasives,” Dietrich says. Perennials are breaking dormancy sooner; the stress it puts on plants causes dieback. Roots are rotting in the excess moisture.
Adapting to climate change means growing different species that are heat-tolerant and drought-resistant. “Try new plants,” Dietrich suggests. “Experiment to see what will do well as we move forward.” He recommends that Richmonders take their inspiration from gardens growing south of us, in zone 8 — in Charlotte and Raleigh, for instance — or look northward to the United States Botanic Garden. “Washington, D.C., is essentially an urban heat island built on a swamp,” Dietrich says, likening the district’s growing conditions to our own increasing heat and humidity.
Zone-hardy Plants
Lewis Ginter Botanical Garden Horticulturalist Dean Dietrich shares five favorites for growing in Richmond’s new normal:
- Sedge is a perfect stand-in for liriope. A grass-like evergreen, it’s available in varieties suited for a wide range of soils and sun.
- Smooth hydrangea blooms on new wood, protecting tender buds from the dangers of spring frost. With its bouquets of fluffy white flowers, it does best in well-draining soil with full sun to part shade.
- Penstemon "Dark Towers" blooms in pale purple trumpets against deeper purple foliage. It thrives in moist, rich, well-draining soil with full sun.
- Tatarian dogwood "Red Gnome" is a compact shrub dogwood whose stems scribe bright red lines in the fall landscape. It grows best in rich, evenly moist soil with full sun to part shade.
- The slender green blades of switch grass "Shenandoah" are brushed with deep-red highlights. Plant it in evenly moist soil with exposure to full sun.
