You might think a nurseryman would have a collector’s garden with rare and choice specimens of every kind, but with only one or two of everything. My garden didn’t turn out that way. I chose minimal watering, only 5-7 times a year, with plants anybody could grow organically, and with strict limits to time and money spent on maintenance. After 29 years, the original xeriscape at Harlequin’s Gardens Nursery turned out to be a naturalized garden. There are natives and unusual plants in this garden, but it is dominated by good or useful “weeds” that make big splashes of color or create a living mulch and thrive with little care. And it changes without my permission, though, of course, I am the gardener, so I get to have some influence.
When I say my xeriscape garden has naturalized, I mean it has filled in and settled in, becoming dynamically stable. The most dominant and best-adapted plants in their particular locations have thrived and the weaker plants not well adapted have died out or been marginalized. Some plants have “moved”, spreading to a more favorable spot (like against a rock) and dying out where originally planted, and some have moved through seed falling, or being vectored by wind or bird.
Many of our customers say they garden following the “Darwinian” method of letting nature sort out the plants best suited to their gardens. Although this function of Nature is often called “survival of the fittest”, I have read that Darwin’s actual meaning was survival of those that best fit the conditions. This also sounds like “sustainability”. But as we gardeners know, conditions change, so when they do, previously dominant species may be replaced or overshadowed by plants currently better adapted. Some old stars of my garden have actually died out in an extra dry, wet, cold or hot year.
GOOD OR USEFUL “WEEDS”
When I say my xeriscape garden is dominated by useful “weeds”, what I mean is, plants that might be too aggressive in a garden that is watered twice a week or more, but which are highly successful with 5-7 waterings a year. I do not cultivate weeds on the Colorado Noxious Weeds list like Donkey Tail Spurge, Butter and Eggs or Perennial Pea. Nor do I allow obnoxious weeds sold at some nurseries like Snow on the Mountain (Aegopodium) or Mock Strawberry (Duchesnea). Those kinds of weeds are a maintenance nightmare. They have aggressive root systems that make them very difficult and time-consuming to remove once they get established.
The highly successful “weeds” in my garden must justify their water and efforts to discipline them by providing big splashes of color, a living mulch weed control, nectar or other support for bees and beneficial insects, sculptural interest, a special foliage color or texture, bloom when little else is in bloom or thrive where nothing else succeeds.
GOOD “WEEDS” FOR COLOR
It took me 2 or 3 seed plantings to get California Poppies going, but they have splashed their orange color in my garden almost every year since they started, with no help from me but some thinning. Blue Flax does so well, I always have to pull some where it is too thick or crowds a more valuable plant. There are always plenty of their beautiful sky blue masses to make my garden look lush even in a dry year. Then the old-fashioned Bachelor’s Buttons add masses of a taller blue, though they have been few lately.
Oh, my! Then the Orange Horned Poppy (Glaucium) steals the show with its shrub-like size and glowing orange flowers with black basal spots. I don’t know where the blue and pink Larkspur (Consolida ajacis) came from, but it’s a glory and a terror. If it didn’t save my dry garden from boredom in July, I’d take it out because it self-sows SO much. But they are easy to pull and I try to limit them to a couple areas.
Other big shows in the garden are the Lamb’s Ears with their fuzzy gray leaves and purple flowers, the luscious Lauren’s Grape purple poppy, Clary Sage with its stinky leaves and elegant flowers, Tall Globemallow (Sphaeralcea) with 6’ stalks of soft orange or pink flowers and Aethionema grandiflora with pink mounds over really blue foliage. We also have various ornamental Horehounds (Marrubium) with very attractive foliage and flowers that are not that exciting to humans, but are one of the main attractions for the bees. These must be dead-headed before they go to seed and/or seedlings must be heartlessly removed, or they will take over. Marrubium rotundifolia is the exception.
Probably some of you are horrified by this list of thugs, but in a dry garden where the ground is mostly covered, they provide color and nectar and pollen through the season, with little care.
GOOD “WEEDS” FOR GROUND COVER
The first plants to survive my severe xeriscape in 1986, after all my Midwest woodland wildflowers died, were sedums. I have been criticized by Bob Nold, my friend and ally (in the cause of genuine xeriscape), for having too many sedums. And he’s right. But my defense and rationale is that those sedums keep the weeds down, require little water, add some serenity (boring areas), add color in winter with their foliage and in summer with their blooms, and provide food for the bees as well. They spread freely, making a 2 ½” plant a bargain in money and labor. And their root system is not invasive, so they are easy and fast to remove if and when I do have something to put in its place. I like the variety of flower colors, foliage colors, heights and bloom times.
My other favorite ground covers in the garden are the many forms of Creeping Veronica. The Turkish Veronica liwanensis is a winner, along with Thyme-leafed Veronica oltensis, later-blooming Veronica prostrata and its gorgeous purple-pink variant ‘Dick’s Wine’. There’s silver-leafed Veronica tauricola and very xeric Veronica cuneiifolia. All of these are evergreen so the weed grasses don’t get a toe-hold before leaves cover the ground in the spring. And they have wonderful blue flowers in spring that flow in dense drifts.
Other groundcovers that hold a place in my original xeriscape garden include: Tanacetum densum, (Partridge Feather) with silvery cut leaves in wide masses; Betonica foliosa with interesting foliage and small purple flowers; it has refused to die for 27 years; Centaurea bella, a lilac-pink perennial Bachelor’s Button; Iberis sempervirens, the evergreen, pure white-flowered Candytuft, now four feet across; and Hen and Chicks with their multitudinous rosette forms and suggestive summer flowers that bees adore. I can’t leave out Plumbago with its true blue flowers and red fall color and the Helianthemums with their many colors of flowers and short-lived but reseeding ways.
I would call Whiplash Daisy, Erigeron flagellaris, invasive, except that it is incorrect to call any native “invasive”. That also goes for the annual Erigeron divergens, both of which came uninvited and refuse to leave.
There are other non-thug plants that have naturalized in my garden and some great shrubs and small trees, but they will have to wait for another article.
When I looked up “naturalized plants” on the internet, to see if my definition was off the wall or on the wall, I discovered that “Natural Gardening is a movement,” Daisy Moore says, “away from fussy, formal and high-maintenance flowerbeds…In a naturalized garden, habitats are created for many animals, insects and micro-flora—the basis for a stable ecosystem.” I like that. I was aiming for some level of sustainability in my xeriscape. But a descent garden does require guidance, even in a naturalized garden. When nature provides too much of a good thing, we can remove some. When space calls for another plant, we can supply one before Nature does. We can pull weeds, we can water and we can cultivate. We gardeners are part of Nature too.