Capitol Hill, get ready. Nature is calling on us to be better land stewards. We all have the power to enhance and improve our local landscapes. The well-known entomologist at the University of Delaware, Dr. Doug Tallamy, says “every square inch of planet earth has ecological significance, even where we live, work, and play.” He believes that by choosing ecologically effective plants and removing invasive ornamental plants, we can make a huge difference in determining nature’s fate. In simple words, plant native.
Smithsonian’s Alex Dencker
Alex Dencker recently spoke to the Capitol Hill Garden Club about using native plants and replacing invasive ones. A horticulturist, he has spent his entire career working with plants. He grew up in Silver Spring and attended the University of Maryland. Currently Dencker oversees the Smithsonian’s National History Museum gardens at 1300 Constitution Avenue having joined the garden staff in 2012.
His working knowledge of plants comes from a long career at the now-closed nursery garden center, Behnke. The nursery was one of the largest and best-known garden centers in the US. “I really learned so much working at Behnke’s because they were so careful with the kind of plants they offered,” he says.
Dencker says that 70 percent of your garden or landscape should be planted in native type trees and plants. “I am hoping over time to reclaim the landscape around the History Museum to include more native plants.” On the east side of the museum at the corner of 12th Street, the Museum maintains Victory Gardens. They are designed to demonstrate what the World War II gardens looked like. “The gardens give us a great way to teach history before visitors even step inside the museum,” says Alex, “and have been a great way to introduce native plants in the raised beds.”
One of the first steps in getting a better hold of your garden spaces is to rid them of invasive species of plants. Over time, invasive plants, think English Ivy or the Bradford Pear in tree species, create a monoculture. They kill off other plants that are essential to pollinators, then impact birds and other animals. “I think of these plants as those that don’t play well with their neighbors,” says Dencker. The Rock Creek National Park maintains the invasive plant atlas, https://www.invasiveplantatlas.org/park.html?id=ROCR, that details 40 species of plants to avoid. The list includes English Ivy, bamboo, common periwinkle, multiflora roses, and Japanese pachysandra. Alex notes that in some cases, like the pachysandra, there are types of species that should be avoided, but other types of pachysandras that are good to plant.
Invasive plants are generally exotic plants introduced to our area often by nurseries because of their beauty or general interest from the public. The plants can reduce biodiversity by growing in a large monoculture and choking out the native plants, changing the soil chemistry that shifts the local hydrology and reduces the food and habitat for native animals and pollinators.
Planting Natives
I asked him a question that has always perplexed me—what is a native plant, because aren’t all plants native somewhere? He laughed at this question, but also said it was one he had wrestled with himself. “The safest way to think of a native here in the DC area is to think of any plant east of the Mississippi.” In addition to researching the origins of a plant, looking into its hardy zone rating, and its temperature zones, are good indicators for the success of a plant. “Clearly, a plant that grows well on the coastal lands of the mid-Atlantic will have different needs, then one grown in a mountain region, says Alex, “but with the warming changes in our area, looking at more southern plants may prove successful in our future.”
“I really think there is such a good variety of native plants out there,” Alex says, “that gardeners can really create stunning gardens and help restore the ecology at the same time.” That said, Alex also says mixing a few non-native plants into your garden is fine.
For instance, Russian Sage and members of the mint family can make great additions to your plantings. National Audubon maintains native plant lists that include information on what birds will be attracted to your garden if planted, https://www.audubon.org/native-plants/search?zipcode=20003.
Lahr Native Plants Symposium
On Saturday March 25, 2023, from 9:30 am to 3:45 pm, the US National Arboretum will host the 36th annual native plant symposium. Sarah Strickler, Educational Specialist at the USNA, says that there is space for 140. “You don’t have to be a master gardener to attend. Especially this year there will be sessions for beginner’s starting to design their land, and several lectures that are more historical.”
The afternoon session with Dean Norton is one that should interest local gardeners and historians alike. He will be discussing George Washington’s efforts to relandscape his Mount Vernon home with native tree and plants often dug up from nearby forests. Dean is the Director of Horticulture at Mount Vernon and has spent 54 years managing the estate.
There will also be a talk on Conserving the Serpentine Ecosystem at Soldier’s Delight Natural Environment Area in Baltimore County, Maryland. Paula Becker is an ecologist with the Maryland Department of Natural Resources and has worked for more than 25 years on a variety of conservation and endangered species programs. The effort is to restore 1000 acres of the serpentine ecosystem that contains oceanic rock and inhospitable growing conditions. The talk highlights efforts to remove invasive species, prescribed burns and other tactics used to restore the area.
Registration for the all-day symposium is required and the event costs $100 for the day, with a discount for FONA members ($80). The cost provides for all sessions, coffee, and snacks, as well as a box lunch. To register go to https://www.usna.usda.gov/visit/calendar-of-events/36th-annual-lahr-native-plants-symposium. Word to the wise, register early, as it might sell out.
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Native Plant Sale March 25
The Friends of the National Arboretum will be selling native plants March 25 from 8:15 a.m. to 2:00 p.m. on Meadow Road, that runs between the Arboretum’s Visitor Center and the National Herb Garden. The plant sale is free to the public, advanced registration is preferred but not required. To sign up go to www.fona.org
Rindy O’Brien can be contacted at rindyobrien@gmail.com.
