Xeriscape

by Steven Hightower, Master Gardener

Xeriscape is a term that was coined and trademarked by a water department task force in Denver in 1978, and refers to water-wise, climate-appropriate gardening. It derives from the Greek term xeros, which means dry, and landscape. Xeriscaping is not necessarily a parched, barren look, nor a no-maintenance (e.g., all rock) approach. Xeriscapes can have color, blooms, lushness and even a certain amount of turf. They are not incompatible with Mediterranean-style gardening or habitat gardening. A properly designed and implemented xeriscape can significantly reduce (but not eliminate) maintenance, and it has been estimated that it can reduce water use by up to 60 percent.

According to the Denver 'founders' there are several basic principles of xeriscaping:

Climate-appropriate plant selection
Superior garden design
Efficient, non-wasteful irrigation
Extensive mulching
Minimal turf areas
Conservation of water in soil
Proper maintenance

Climate-appropriate plant selection means those whose water needs are closely suited to local water availability. Here in Sonoma, where we have a dry summer wet-winter Mediterranean climate, those plant varieties that are appropriate are those that survive on little summer water—see the list at the end of this article. Natives are always a choice that is in line with xeriscape principles.

Efficient, non-wasteful irrigation generally means drip, with the exception of effective

sprinklers for densely planted areas of ground cover or bunch grasses. The term hydro-zoning refers to the practice of grouping plants by their water needs, so that just the right amounts of water can be given, which avoids both over and under-watering of particular plants. Each zone uses a separate valve, whether the method be drip, soaker or sprinkler, ensuring that each zone may be programmed independently.

Mulching helps moderate soil temperature, reduce evaporative water loss, and keep down weeds at the same time. Chipped or shredded barks are the most common mulches, but gravel and stones may be used as well. Soil amendment with compost both provides nitrogen for plant growth, and improves soil structure for water conservation.

Regular maintenance is not eliminated in xeriscaping. Pruning and fertilizing are still required, as is weeding, although mulch and drip irrigation will reduce weed germination considerably. Irrigation systems must be periodically tested, and seasonally adjusted. Pest management is still required, and both organic pest management, and IPM, or integrated pest management, are practices that are very consistent with the ideology of xeriscape.

Replacement of traditional lawn with ground covers or lower-water bunching grasses is a key element in xeriscaping. Ground covers such as creeping or wooly thyme, and grasses such as the dwarf versions of blue fescue, fountaingrass, and deer grass can serve much the same visual and use purposes as turfgrass, and require much less care and water than a lawn.

A small, far from extensive, list of xeriscapic plants appropriate for Sonoma County includes:

PERENNIALS

Rosemary, lavender, yarrow (achillea species), santa barbara daisy (erigeron), gaura, mexican sage, salvia greggii, verbena bonariensis, phlomis, kniphofia, catmint and dusty miller (lychnis) are good choices.

VINES

Honeysuckle, wisteria, potato vine and grapevines all work as xericsapic choices for climbing vines.

GRASSES

Many grasses are fairly drought tolerant: fountain grass (Pennisetum alopecuroides), blue oat grass (Helictotrichon sempervirens), blue fescue (Festuca glauca) sedge (Carex variegate) and deer grass (Muehlenbergia rigens) are all appropriate.

SUCCULENTS

Agave, aloe, hen & chickens (Sempervivum tectorum), sedums, and echeverias.

ANNUALS & BULBS

Summer dormant bulbs such as iris and daffodils are well adapted to drought-tolerant gardens. Many early-year blooming annuals work well in xeriscapes, although supplemental water may be needed for annuals more than other drought tolerant plants: California poppies, lupine, bachelor buttons, clarkia, larkspur, alyssum and lobelia all work.