By Sarah Vradenburg
Each week, Signal Akron will help you in your gardening adventures with an excerpt from "The Root of It," a monthly newsletter from the Summit County Master Gardeners, Ohio State University Extension.
As I look down my driveway, all I can see are the weeds that have taken over the cracks in the pavement. While they make me want to tear my hair out, they remind me that not all gardening takes place in flower beds. When I take a walk through the sandstone ledges that are scattered liberally throughout this region, I marvel at mature trees growing out of the sides of towering rocks.
Both these scenarios are perfect examples of crevice gardening, planting in small spaces between rocks. Stones are wonderful in themselves, but when enhanced with various textures, colors and shades of green, they come to life.
Using gaps in stone to garden shows off plants that might not be well-suited to traditional flower beds. Think of sedum, those drought-tolerant plants that can grow just about anywhere but seem to thrive in dry, inhospitable nooks. Hens and chicks (Sempervivums spp.), add a touch of whimsy as they multiply their spiky rosettes in places you might not have thought possible.
Woolly thyme (Pseudolanugiosus spp.), creeping phlox (Phlox stolonifera, spp.), rock cress (Arabis causasica) are all stone stalwarts, growing in niches in a barn stone wall, cascading from ledges, or simply spreading out on a rocky outcrop.
Crevices are great places to show off unusual plants. Moss rose (Portulaca grandiflora) is a natural. It is heat and drought tolerant and insists on living in full sun.
Sea thrift (Armeria maritima) is ideal for larger pockets, with its mounding habit of spiky, almost grass-like leaves that sprout small flowers, ranging in color from pink to white to almost red. The drier the better for this plant, which rots if planted in moist soils.
Cliff maids (Lewisia spp.) is named for Meriwether Lewis, who found it in the west high country he surmounted on his travels to the Pacific. It is native to that area, thriving on north-facing cliffs and rocky outcrops. Some species are deciduous, some evergreen, all are succulent and with captivating flowers. Because it’s native to higher northern altitudes, our growing zones are no obstacle.
Building a crevice garden requires rocks, although that doesn’t mean visiting quarries and renting heavy equipment — that’s a lot of money and labor. These gardens can be built on a slope, tucking plants into the spaces formed by found objects (old tools, bricks, unusual hunks of concrete).
An essential ingredient is turkey grit, crushed granite that serves as the foundation for the garden and ensures that drainage will be adequate. Do you have a dry spot that turns flowers to dust? Find flat rocks and embed them on end in a layer of grit.
The key is sharp drainage, which allows water to flow easily through the garden. Plant between the standing stones. Or, if space is a consideration, create a crevice garden in a container. Hypertufa troughs hold the grit. Add unusual stones or small rocks and your favorite desert flowers. Voila!
If you already have a perfect outcropping of your own or nature’s making, scrape out and set aside the material between the stones. Wash most of the soil off the roots of your plant and gently tuck it into the crevice. Replace the soil, making sure it’s snug around the roots. Give the area a light watering the first couple of weeks to be sure the roots are established. That’s it.
Nature is always willing to show off her myriad creations. Sometimes she provides dramatic backdrops, sometimes tiny niches hold the beauty. Crevices may be small, but the impact they have can’t be hidden.
Resources:
“Try This, Not That: Crevice and Rock Gardening”, Sarah P. Duke Gardens
Crevice Gardens: Life Between the Cracks: PennState Extension