Given the container craze that's overtaken the gardening world, and longtime interest in homemade "hypertufa" troughs that mimic naturally porous tufa rock, Mackey thinks crafts-minded gardeners may soon embrace papercrete, too.
"Mud Pie 101," she calls it.
Truth be told, it does look like a mud pie, this therapeutic mix of finely shredded newspaper or junk mail, common Portland cement, sand or perlite, and water. Outfitted in face mask, rubber gloves, and apron, Mackey kneads it into a muddy ball, like bread dough, in a plastic tub on a fold-up table draped in plastic.
She squeezes lumps and corrals rogue paper scraps as she goes, insisting, "It's not rocket science."
When the consistency is just right, not too dry or too wet, the blob is gently pressed into a plastic lid from a store-bought carrot cake. Which means that after "curing" for a day or two in Mackey's Wayne garage, her molded planter looks pretty much like an ossified bundt cake.
But artfully filled with dwarf conifers, jewel-toned sedums and saxifrages, tiny tufts of moss and rock slivers, this simple trough garden turns complex and interesting. Now, it's darkly ancient, rough-hewn, and weathered, as if lifted from a craggy crevice in the Dolomites.
That's the right look for Mackey, president of the North American Rock Garden Society's Delaware Valley chapter. "It goes with my garden, which is very naturalistic," she says.
For decades, environmental adventurers with a naturalistic bent have been experimenting with papercrete, which they saw as cheap, lightweight, easy to work with, good insulation, and aesthetically correct. Although it recycles paper, it's not particularly "green" because of the cement, the making of which generates huge amounts of carbon emissions.
In the 1990s, some free spirits fashioned adobe-like bricks and blocks out of papercrete to build houses, garages, and sheds, mostly in the West and Southwest. Among them were Kelly and Rosana Hart, founders of the www.hartworks.com Web site about "green home-building" and sustainable architecture, who used papercrete plaster for their "earthbag" - sandbag - house in Colorado.
They now live in Mexico, and Kelly Hart estimates that fewer than 100 papercrete structures have been built to date. "Not very many people really know much about papercrete, and it has yet to prove itself as truly viable over time," he says.
Mackey had never heard of any of this until 2005, when she went online to find something new to spice up her standing-trough lecture. Up popped the funny-sounding "papercrete," not in the context of gardens or planters but on Web sites devoted to "green" building materials and alternative-housing projects with names like "Casa WizardMoon" in the Arizona desert.
"I thought, man, if you can make a house out of this, I can certainly make a papercrete trough," says Mackey, who since then has made a how-to CD and will host a papercrete workshop at Longwood from 9 a.m. to noon on April 23.
Patty Volpi of Wayne took Mackey's Longwood workshop last spring. Long a fan of traditional container gardening, she was intrigued by the idea of a more natural-looking trough to showcase "unique plants with beautiful coloring and different textures in small form."
Volpi hasn't made her own papercrete trough yet, but hopes to do so. For now, using Mackey's planting suggestions, she has filled a terra-cotta-colored, plastic window box-planter with two dwarf Japanese maples, some small campanula, and a variety of sedums, hens and chicks, and other succulents.
The ensemble is soft, feathery, chunky, low-riding, and upright, with some cascade over the side. "It has different forms and colors. I feel I can be creative with the plants I put in," says Volpi, a longtime stay-at-home mom and hobby gardener, who recently began working as an assistant horticulturist at Chanticleer, the public garden in Wayne.
Alpine or rock-garden plants can be finicky, but they seem to grow well in papercrete troughs. They also have the right scale for most small to medium troughs, which should be planted, as Mackey says, "with a lot more restraint" than other containers.
The design should be spare and simple, and incorporate small rocks and "little-bitty pebble chips. There shouldn't be that much going on. It should look very natural," Mackey says.
One plant should be a one-season bloomer, but flowers aren't a requirement. You can use all succulents or all moss, for example.
Unlike so many gardening fads, trends, or traditions, papercrete planting isn't about what's "hot" or big or colorful. It's about architecture and placement.
"It's not a wildly showy form of gardening," says Mackey.
Even so, it's been known to cause rapid heartbeat to folks like Mackey, an affliction most gardeners - happily - live with.
Contact garden writer Virginia A. Smith at 215-854-5720 or vsmith@phillynews.com.
