A recent letter began, "We have a steep slope covered with a pink-flowering ice plant that died in this year's freeze." The writer then asked: "Bearing in mind the water situation, can you suggest another ground cover? We have thought of vinca minor."
The solution is not another ground cover, because any single planting is liable to disappear at any time leaving a very barren slope. It might be a freeze that does it in, or unusually hot weather, or drought, or root rot or some bug, but if an entire slope is planted to one kind of ground cover, it is always vulnerable to whatever comes along.
Remember the trailing African daisy, that white-flowered ground cover that once lined Southern California freeways? Seen any lately? Most succumbed to root rot, a rather grand example of not putting all your ground-covering eggs in one basket.
Environmental designer Cynthia Hirschhorn has a better idea, as demonstrated in her own garden. "I planted tons of things," she said, "a great mix of plants." Her slope in Pacific Palisades is a veritable tapestry of drought-resistant hill-holders.
Here and there one can find a plant in trouble, or one that has died, but it leaves only a small tear in the tapestry and it is easy to mend--quite different from losing an entire hillside of one ground cover.
"Having a theme is important," added Hirschhorn. Otherwise the hill becomes a hodgepodge. Here the theme is of low and undulating plants and the colors are controlled. Only shades of lavender, blue, purple or pink are allowed.
For instance, where there might be only pink ice plant in a conventional hillside planting, here there are four different purple flowers in one small area: ground morning glory Convolvulus mauritanicus, lavender, trailing rosemary and Mexican salvia.
There is also a variety of plant sizes--some large, some low--which makes the garden much more interesting. Overall, however, most of the plants are low so they are not a fire hazard.
How did Hirschhorn choose these plants? "I studied every picture I have ever clipped from a magazine, I looked through all the Penelope Hobhouse books and then I looked up every plant I liked, to see if it was drought resistant, and if it would grow in California.
"I visited a lot of nurseries, including ones like the Theodore Payne Foundation in Sun Valley (a nursery located in the San Fernando Valley that specializes in native plants; there are a number of natives on the hillside). I did a lot of research."
If you want to know whether it grows in California, try the "Sunset New Western Garden Book" (Lane Publishing, Menlo Park). On pages 126, 161 and 167, there are also good lists of plants for dry hillsides. This book is commonly available at nurseries and it was one of Hirschhorn's many references.
That extra work and research made the garden an instant hit on a recent architectural tour. Everyone remarked about the exuberant plantings.
They also enjoyed what one visitor called "the journey" through the garden on the flagstone paths. These wind through the garden so all of the plants can be visited, and cared for. Here and there they widen to become little sitting areas. Some of the plants in the garden grow in the gaps between stones.
Although Hirschhorn has a master's degree in architecture, she did not make blueprints or draw plans for the paths or the garden.
"I drew it on the ground so I could fit it to the site," she said. "I marked out the paths with sticks, stones and even made lines in the dirt."
That's probably the best way to design a garden for yourself, especially one on a hillside.