A No-Water Garden

July 2nd, 2012

    Even in this past bake-oven summer with its 99-degree days and weeks without rain, Jenny Rose Carey didn’t put a drop of water on her garden.

Jenny Rose Carey's dry garden.

   In fact, she hasn’t watered it in 6 years.

   Ask her what’s died in that time, and she’s hard-pressed to name anything.

   How can that be?

   Gravel, smart plant selection and “lean-and-mean” plant care.

   Carey, director of Temple University’s Ambler Arboretum, has been experimenting in her home garden with an East-Coast version of what’s known as Xeriscaping in the arid Southwest.

    She seems to have come up with a game plan that makes it possible to grow a water-free garden that doesn’t look like Arizona.

   “This year was a really good test year,” says Carey, who grew up in England.

   When she married a Pennsylvanian and moved to a 4-½ acre property in suburban Montgomery County, watering became a top issue.

   “We’re on a well,” she says. “When we moved here, there was no outdoor spigot. I had my watering can.”

   What really nailed it down was when Carey visited Provence, France, in 2003.

   “I saw lavender growing by the side of the road in road chippings,” she recalls. “I thought, ‘I’m going about this all wrong.’”

   When she got back, she decided to carve out a “dry garden” the size of a small hockey rink next to her cherished herb garden (the one with the “Ring for Jenny” bell in front).

   The framework is a native bluestone path that loops around a central sitting area that’s shaded by a trumpet-vine-clad pergola.

The pergola-covered sitting area that's the centerpiece of Jenny's dry garden.

   Wide, curving, raised beds of assorted perennials, shrubs, evergreens, groundcovers and reseeding annuals surround the path and patio.

   Carey raised the beds for two reasons: “It helps with drainage and brings the flowers up closer to you.”

   She skips compost and says the ideal soil amendment is instead something gritty, such as gravel or chicken grit from the farm-supply store.

   She contends that we lose far more plants to rotting in poorly drained soil than drought.

   Pressed for time, though, Carey built her dry-garden raised beds with a few truckloads of ordinary topsoil. Nothing was worked into it.

    She then covered the beds with 2 to 3 inches of smooth river pebbles – between the size of a pea and a marble.

    She says that lets plants breathe better than the smothering, fast-crusting wood mulch that most gardeners use.

   When it does rain, water soaks into the soil immediately instead of having to penetrate the mulch layer first.

The stone mulch in Jenny's dry garden.

   If you’ve ever watered a dry, wood-mulched bed, you’ve also probably noticed how surface tension causes the water to run off at first. In heavily mulched gardens, it may take a quarter- to half-inch of rain before any of it actually gets to the plant roots.

   “I plant so the crowns (the point where leaves emerge) are surrounded by stone, not soil,” Carey says. “And this is really important – I don’t just take the plant out of the pot and plant it. I remove nearly all the soil and plant almost bare-root.”

   Why?

   “So much of planting mix is peat, and when that dries, it’s hard to re-wet,” she says.

   Carey believes new transplants are quicker to root into the native soil when the potting soil is removed.

   The third main prong of her no-water experiment was plant selection.

   She started with the premise of wanting a garden, not Death Valley.

   “I didn’t want any cactus,” she says. “I don’t even like cactus. But I do like things that self-sow.”

   So she started with species such as California poppies, larkspur, nicotiana, Verbena bonariensis, cleome and butterfly flower.

   Those not only are good at planting themselves each spring, they get along without the water needed by greenhouse-grown impatiens, petunias, coleus and the like.

   Then she looked to plants at home in Mediterranean and dry climates – primarily plants with waxy-coated leaves that limit evaporation loss.

   Most of those are recognized by their blue and silver leaves — species such as lavender, artemisia, caryopteris, dianthus, euphorbia and agastache.

   And to those she added succulents and rock-garden stars, such as sedums, hens and chicks, yucca and the sun-tolerant Rocky Mountain columbine.

   “It was a bit of research, a bit of common sense and a bit of guessing,” Carey says. “One pleasant surprise that worked out very well was Pulsatilla vulgaris.”

   Nicknamed “pasqueflower,” this one is a lavender-blooming perennial that looks a bit like hardy geranium.

   Carey purposely doesn’t fertilize.

   “I don’t want to molly-coddle the plants,” she says. “The whole idea when you add nitrogen (fertilizer) is that you push new growth. That just encourages aphids. I want my plants to be short and stocky.”

   Carey’s “lean-and-mean” approach, as she calls it, may not produce absolute top-notch plant performance, but the tradeoff is good bloom, no need to stake most plants, no watering and no fertilizing.

   Since stone mulch doesn’t break down, Carey also doesn’t add new mulch every year – just occasional fill-ins where the stone thins due to movement or migration into the soil.

   Her main work is “editing” out the self-seeders and policing for weeds – mainly oxalis.

   Want to give this a try?

   “Start in a small area and see if it works for you,” Carey says.

   It’ll take some grit (in more ways than one), but your checkbook will thank you at water-bill time.