This is actually serious business to Eberle and Caprioli, who - like the scientists they are - are promoting their native-plant beliefs by explanation and example, educating one neighbor, relative and coworker at a time.
"My neighbors are always asking, 'What's that in your yard?'" Eberle says, "and I'm happy to tell them."
Gardeners are not known for their rigorous planning and precise execution. Sounds great, doesn't it? So do small portions and getting plenty of exercise.
Really, who consistently thinks about right plant, right place, soil composition, sun vs. shade, how big the thing will eventually get, and what its ecological impact will be?
Five years ago, Eberle and his wife moved to their 1950s subdivision, where the prevailing landscape consisted of everything from someplace else: English ivy, Norway maple, Japanese pachysandra, Chinese saucer magnolia and burning bush.
Eberle's native replacements offer nourishment and nesting space for our indigenous, and rapidly disappearing, birds, butterflies, and insects. Historically adapted to conditions in this part of the world, they nonetheless remain less familiar to gardeners and stubbornly underused in the landscape.
A partial list: winterberry, spicebush, foamflower, Joe Pye weed, sweet pepperbush, wood poppy, Carolina allspice, serviceberry, and Virginia sweetspire.
Among Eberle's favorites are the clove-scented spicebush, an important host plant for the spicebush swallowtail and the Eastern tiger swallowtail butterflies, and serviceberry, whose small red-purple berries are prized by birds - and humans.
Eberle puts serviceberries on his cereal and bakes them into muffins. They taste like complicated blueberries, hinting of blackberry and grape.
At this time of year, Eberle's landscape is an elegant understatement of white blossoms and green foliage, which seems to bolster the notion that natives aren't colorful.
They can be. Eberle also has purple blazing star and coneflower, pink milkweed, red bee balm, and magenta garden phlox.
All this may sound like a half-acre mash-up. Not at all.
Eberle is nothing if not thoughtful. Case in point: His may be the only yard in America without a single tomato plant.
"Last year, my tomatoes got the blight," he explains, "so I'm taking a break."
Experts recommend giving the blighted bed a rest, meaning either plant your tomatoes in a different spot the next year or skip them for a summer.
And so he is.
Dan Caprioli discovered native landscapes as a biology major at Mansfield University and then, like Eberle, on the job. Even earlier, though, he gravitated to growing.
As a kid visiting relatives in the Poconos, he marveled at the terraced gardens of his Italian great-uncle, Louie. And at 16, having come upon Square Foot Gardening, Mel Bartholomew's intensive planting guide, at the library, Caprioli persuaded his parents to give him a 36-square-foot vegetable plot behind their Souderton rowhouse.
"I never liked vegetables growing up," he recalls, "but when you grow your own, they taste great."
Now this sophisticated gardener has two 20-by-20-foot raised beds behind the Harleysville house he shares with his wife and 18-month-old son, Leo. (No. 2 is on the way.)
The beds overflow with Roma tomatoes, asparagus, beans, and peppers. Caprioli, 50, cultivates many fruits, too, among them peaches, apples, currants, pawpaws, grapes, blueberries, raspberries, strawberries, and elderberries.
He makes many kinds of wine, grows from seed, and propagates plants to fill out his landscape or share with friends like Eberle, who responds with gifts of his own.
Native milkweed, bee balm, and coneflower bring a parade of birds and butterflies, including endangered monarchs, to the property, proof that one need not have major acreage to create a vibrant wildlife habitat.
It's tempting to lecture people about the benefits of natives, but people get irritated," Caprioli says. "It's better to let them see what you have."
Of course, what attracts the good guys also appeals to the bad - marauding groundhogs, deer, rabbits, Japanese beetles, and the occasional slug.
"It's a lot of work, but everything worth having is worth working for, right?" says Caprioli, who began this grand adventure by drawing a master plan to scale on graph paper, including tree measurements, sunny/shady areas, and where the beds would go, followed by testing and then improving his clay soil with sand and mushroom compost.
Caprioli spends all his free time - his commute to Center City takes three hours a day - working in the garden.
He realizes this won't fly for most people. "This is why we have microwaves," he says.
But Caprioli is not "most people." He values the planning, the long view, the five years of hard work that will turn into five more and five more.
His garden, mostly hidden from the street, is a native wonderland set incongruously among traditionally landscaped suburban homes, office buildings, and senior apartments. It may be the only one on the block, but perhaps, someday, that will change.
"This is my sanctuary," Caprioli says, as three blue jays flutter away from one of theirs, a huge currant bush loaded with tiny red berries.
These books helped shape Mark Eberle’s and Dan Caprioli’s views on native plants and the natural world:
"A Sand County Almanac: Outdoor Essays and Reflections" by Aldo Leopold, Ballantine Books, 1986.
"Bringing Nature Home: How You Can Sustain Wildlife with Native Plants" by Douglas W. Tallamy, Timber Press, 2009.
"Native Alternatives to Invasive Plants," Brooklyn Botanic Garden, 2011.
"Native Plants of the Northeast: A Guide for Gardening & Conservation" by Donald J. Leopold, Timber Press, 2005.
"Great Natives for Tough Places," Brooklyn Botanic Garden, 2009.
Bowman’s Hill Wildflower Preserve, www.bhwp.org/
Lady Bird Johnson Wildflower Center, www.wildflower. org/