Garden Styles: Xeriscape
(Editor's Note: This article was originally published on February 22, 2008.)
Xeriscaping* is a term coined and trademarked by the Denver Water Department in Colorado, and means designing an area with drought conditions and reduced water consumption as the focus. This doesn't mean green concrete decorated with boulders, although at times that seems very appealing to me! Southwestern states have used these practices for years, but the day is coming when we all need to better utilize our water and land resources if we don't want to end up with green concrete. According to a 2004 press release by Santa Fe Greenhouses/High Country Gardens, "properly maintained, a xeriscape can easily use less than one-half the water of a traditional, bluegrass-lawn dominated landscape."
One-half. Think about that.
Whether you plan to completely redesign your landscape, or just implement a few xeriscaped areas, hydrozoning is key. Grouping plants with similar water needs and climatic conditions reduces maintenance; cacti and succulents would never be planted with hosta or lilies.
Your property will have three main zones: 1) arid, 2) transition, and 3) oasis.
- Oasis zones are usually close to the house to benefit from rain runoff or the protection of shade.
- Transition zones combine drier areas with those needing low or moderate moisture.
- Arid zones would be farthest from the house and in low-traffic areas; often these areas are natural habitat or planted with native or drought-tolerant specimens.
As with any gardening project, soil, exposure and drainage are important. Drought-resistant plants are usually sun-loving, so they will thrive in that brutally unprotected part of your landscape; most can tolerate some morning shade. Consider where the specimens originated; what are the conditions in their native habitat? Amend your soil to provide a similar environment. Clay soil, especially, is problematic for almost all plants, as it does not absorb water easily, nor drain quickly. Check all specifications for any plant you are considering for a clay-dominated area.
Even drought-tolerant species must be watered to become established. Water these new specimens the same as you would normally; but be aware that frequent shallow watering promotes shallow roots that are not as efficient in a xeriscape system. Shrubs and trees will need a minimum of two growing seasons to settle in before you reduce watering. Perennials will usually be up to the challenge by the year following planting.
Mulch plays an important part in the xeriscape plan: 1) moisture conservation, 2) erosion control, 3) weed reduction, and 4) aesthetic value.
Most sources recommend organic mulch, which is wood based. By decomposition, organic mulch improves the soil over time; however, it does need to be replaced regularly (hardwood mulches seem to last longer, but are more costly). Apply mulch 2 to 4 inches deep, keeping the material well away from stems and trunks.
Inorganic mulches such as stone or gravel can be used in some instances, but never in locations that receive direct sun, as the material absorbs heat. When using stone-based mulch, be sure to use weed-barrier landscape fabric to help cut down on the maintenance of this area.
Common plants to most regions include agave, lavender, juniper, sedum, thyme, lantana, euonymus, and many herbs. The following suggestions are compiled from both the Colorado State University Extension publication1 and the afore-mentioned press release from Santa Fe Greenhouses/High Country Gardens2; most of them will flourish in a wide range of zones. A little further research will show you what other specimens might fit into your particular region and situation.
Apache plume (Fallugia paradoxa)
Barberry, Japanese (Berberis thunbergii)
Bladder-senna (Colutea arborescens)
Ceanothus (Ceanothus fendleri)
Cinquefoil (Potentilla fruticosa)
Cliff rose (Cowania mexicana)
Cotoneaster (Cotoneaster spp.)
Lead Plant (Amorpha canescens)
Mountain mahogany (Cercocarpus spp.)
Peashrub (Caragana spp.)
Privet (Forestiera spp.)
Rabbitbrush (Chrysothamnus spp.)
Rock Spiraea (Holodiscus dumosus)
Sage (Artemisia spp.)
Saltbush (Atriplex canescens)
Sand cherry (Prunus besseyi)
Sea buckthorn (Hippophae rhamnoides)
Sumac (Rhus spp.)
Yucca (Yucca spp.)
Catmint, Select Blue (Nepeta x faassenii "Select Blue")
Claret Cup Hedgehog (Echinocereus triglochidiatus)
Curlicue Sage (Artemisia versicolor "Seafoam")
French Lavender (Lavandula spp.)
Giant Thrift-Leaf (Hymenoxys acaulis)
Hummingbird Mint (Agastache spp.)
May Night Sage (Salvia "May Night")
Pineleaf Beardtongue/Penstemon (Penstemon pinifolius)
Russian Sage (Perovskia atriplicifolia)
Burr oak (Quercus macrocarpa)
Goldenrain tree (Koelreuteria paniculata)
Green ash (Fraxinus pennsylvanica lanceolata)
Hackberry (Celtis occidentalis)
Japanese pagoda tree (Sophora japonica)
Kentucky coffeetree (Gymnocladus dioicus)
Pinyon pine (Pinus edulis)
Thornless honeylocust (Gleditsia triancanthos inermis)
Tree-of-Heaven (Ailanthus altissima)
Western catalpa (Catalpa speciosa)
* Xeros (Greek word for "dry") plus landscape = xeriscape.
1. "Xeriscaping: Trees and Shrubs". Colorado State University Extension Horticulture Publication No. 7.229; http://www.ext.colostate.edu/pubs/Garden/07229.html; viewed 1/11/08.
2. "Top 10 Plants for the Ultimate Easy Xeriscape Garden". Press release, Santa Fe Greenhouses/High Country Gardens, December 15, 2004. http://www.prweb.com; viewed 1/11/08.