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What is Xeriscape Gardening?

The word Xeriscape is derived from the Greek word “xeros”, meaning dry, and was coined in the 1980s to describe water-efficient landscaping. The term does not imply doing without any water in our gardens or restricting our plant choices to cacti and a few succulents. Rather, it is about growing beautiful plants in appropriate conditions, reducing the need for water and using our available water efficiently. This fact sheet provides introductory information about establishing and maintaining a water-efficient garden.

How to establish the garden

You can install and maintain a xeriscape garden by adopting some simple strategies:

1. Planning and design
2. Soil conditioning, planting and mulching
3. Watering efficiently
4. Choosing drought -tolerant plants

Planning and Design

1. Microclimates:

   Study the microclimates in your garden and place your plants in the area that matches their needs. Learn where your plants were growing in the wild and try to give them the same conditions in your garden. (An excellent reference to help with this is the series of books by Martyn Rix and Roger Phillips.) A southerly or western exposure will be subject to hot and drying afternoon sun and will suit plants that like sunny and dry conditions. A northern or eastern exposure will suit plants that appreciate more shade and moisture. Plants that require a lot of water might be happy beside a downspout or in a low-lying area that does not drain quickly. You can alter the microclimate of your garden by planting trees and shrubs. Conifers on the north side of your property will buffer the winter winds and give shelter. Deciduous trees on the south side will help keep both your garden and house cooler in the summer while allowing the winter sunshine to penetrate.

2. Watering Zones:

   Divide your garden into different watering zones. The area next to the house or closest to the water supply could be the “oasis” area where high water demand plants, such as turf grass, annuals and plants in containers, could be placed. The middle zone, the moderate water demand area, could be a mixed border of perennials and shrubs, which may need irrigation on an occasional basis. The low-water use zones will require little or no additional water after the plants are established and can be anywhere in the garden but are ideal for areas far from the house where watering is difficult or in well-drained areas.

3. Turf Alternatives:

   Consider limiting the turf area in your garden to where it is functional, such as a play area. Since turf grasses consume a lot of water and are high maintenance, think of using alternatives. Perhaps a gravelled area, a patio or deck could replace some of your lawn. If an area is prone to heavy foot traffic, a paving stone path through groundcovers or mulch would be a good alternative. Use groundcovers, such as vinca and sweet woodruff, in place of grass in dry, shady areas or on slopes where mowing is difficult. Try to eliminate small strips or patches of grass that are difficult to water efficiently.

4. Reducing runoff:

   There are several design decisions that can help you reduce runoff. Try to channel runoff from your house and paved surfaces to supplement the water needed elsewhere. (A rain barrel at the base of a downspout to collect rainwater is an ideal water source for your plants. The water is soft, warm, contains no chlorine and is free.) Using gravel or porous paving such as interlocking brick or flagstone, rather than cement or asphalt, allows rainwater to penetrate the soil and reduces runoff. Terracing a steep slope will help to hold water on it.

Soil Conditioning, Planting and Mulching

1. Organic soil amendments:

   Digging organic matter, such as compost, leaf mould, composted manure, composted pine mulch or coconut fibre into either sandy soils or heavy clay soils will increase the soil's capacity to hold water at the root zone of the plants. Plants with deep and healthy roots are better able to withstand drought. Soil amendments will not only improve the texture of your soil, but will also provide a gentle fertilizer for your plants. Using chemical fertilizers, particularly those high in nitrogen, can encourage lush growth that is less able to withstand droughty conditions.

   Constant cultivation of the soil is not beneficial in a xeriscape garden: it promotes moisture loss from the soil and encourages weed germination. Once you have done the initial preparation of your garden beds, layer the soil amendments on your beds and let the earthworms and other soil organisms incorporate them into the soil.

2. Planting:

   Make sure your plants get off to the best possible start:

   • Before planting, water the plant in its pot thoroughly
   • Dig the planting hole, fill to the brim with water and allow the water to drain away
   • Pull open the root ball of the plant and gently tease out any circling roots
   • Firm in the plant at the same depth that it had in the pot and water again
   • A circular mound of soil, 2-3” high, around the plant will help to hold water at the plant's root zone and can be removed after the plant is established
   • Mulch with an organic or inorganic mulch, ensuring that the mulch does not cover the crown of the plant
   • Water regularly until the plant is established, then decrease the frequency of watering
   • Plant in spring or early fall; planting in the heat of summer can be stressful for your plants

3. Mulching:

   Mulching is one of the best things you can do for your garden and is an essential part of the xeriscape garden. A 2-inch layer of mulch helps keep existing moisture in the soil and reduces erosion and runoff. It inhibits the growth of weeds and moderates temperature extremes within the soil, favouring a healthy population of earthworms and other beneficial organisms. In perennial borders where there is periodic planting and digging, use a fine mulch, such as cocoa beans shells, as it will break down fairly readily in the soil. For more permanent planting in shrub borders or under trees, you could use coarser mulch, such as pine bark chips or shredded bark. One of the best and cheapest garden mulches is your leaves. They can be chopped and layered on the soil or composted and applied as leaf mold.

   Organic mulch is best applied in late spring when there is an abundance of moisture in the soil and can be renewed in late autumn. If you have an area of your garden where you are growing very drought-tolerant plants in a lean and gravely soil, you may want to use inorganic mulch. Xeric plants, such as cacti and succulents, yuccas, lavender, herbs, ornamental grasses and species tulips will thrive with a mulch of gravel or stone and seed themselves about.

Watering efficiently

1. Since the xeriscape garden is divided into different watering zones, apply water at different frequencies for the high demand, moderate demand and low demand areas of planting. Lawns and annuals need about 1” of water per week, whereas other areas of your garden will flourish with much less. Use a rain gauge to keep track of your lawn's weekly water supply. If you have an automatic irrigation system, there should be a separate zone for your lawn to avoid overwatering other areas. Lawns are generally watered using a sprinkler system, but a soaker hose is preferable for watering perennial or shrub borders, because it reduces evaporation and puts water at the root zone where it is most needed. Try to ensure that water is going only where it is needed, not on your patio, driveway or sidewalk.
2. Water established gardens deeply, so that the water penetrates to at least 8 inches, and only when needed, to encourage deep-rooted plants. (Newly planted gardens may need more frequent watering for the first two years until the plants' root systems are established - a well-rooted plant is the most drought-tolerant.) Wait until your lawn shows signs of stress before watering or allow it to go dormant in the summer. Watch for signs of drought in the flower garden: a wilted plant at the end of a hot summer's day may not need water but if it is still wilted the next morning, some supplemental watering will be necessary. If you have a few plants that need extra watering, water by hand using a watering can - there may be no need to water the whole border.
3. Vary your watering routine to suit the weather and the season. Generally our gardens need much less additional water in the cooler spring and autumn months than at the height of the summer. If you have an automatic sprinkler system you should adjust the timing mechanism once a month or use it only if you are away.
4. To minimize evaporation, water at night if you have an automatic sprinkler system or in the early morning.

Choosing drought-tolerant plants

How can you tell if your plants are drought-tolerant? Knowledgeable nursery staff should be able to point you in the right direction and there are many excellent books and web sites that list drought-tolerant plants in various categories. Make sure your plants are hardy for your gardening zone - borderline hardy plants will likely succumb first to stress or an unseasonably cold winter.

As you study drought-tolerant plants, you will see that they share some common characteristics:

• Natural habitat: Drought-tolerant plants are usually native to dry parts of the globe. While this may seem obvious, especially in the case of desert plants, what may be surprising is the variety of habitats in the world where drought-tolerant plants grow. A typical habitat is a mediterranean climate where cool, damp winters and springs are followed by hot, sunny and dry summers. These weather conditions occur in the countries that border the Mediterranean, but similar growing conditions can be found in coastal California and in parts of South Africa and Australia. From the dry woodlands of both Southern Europe and California come many of our garden perennials able to tolerate dry shade. The Central Asian steppes, extending from Turkey across Asia to northwest China and Mongolia, produce numerous bulbs and hardy drought-resistant perennials. Many of our native North American drought-tolerant perennials come from the prairies and grasslands of the Midwest. Plants which grow together in the wild or which come from similar natural habitats will usually combine and grow well together in your garden if you provide suitable growing conditions.
• Family or genus: There are several families or genus of plants whose members tend to be drought-tolerant. Succulents have thick, fleshy stems and leaves filled with sap and a waxy coating to prevent them from drying out. Sedums, both the low-growing and taller perennial varieties, are popular succulents with their own unique water-saving devices. Pioneer plants, those that first colonize a disturbed patch of earth, come from several families that tend to be drought-tolerant - the grass family (Gramineae), the pea family (Leguminosae), and the daisy family (Compositae or Asteraceae).
• Physical characteristics: Drought-tolerant plants have developed certain types of roots, leaves and other mechanisms to help them survive. Plants with deep tap roots, such as found in the poppy and pea families, can reach water sources that other plants cannot. Members of the lily family, including daylilies, have fleshy roots that store a quantity of water. Trees have wide-spreading roots that can cover a large area to seek moisture.

  There are also adaptations in leaves common to drought-tolerant plants. Generally small or divided leaves allow less water to transpire. Plants with gray or silver foliage tend to be drought-tolerant and hairy leaves and stems are also signs of drought-tolerant plants. Plants with aromatic leaves such as lavender and culinary herbs, such as thyme and rosemary, are also drought-adapted.

  Sometimes a plant's habit of growth will indicate drought-resistance: many drought-tolerant plants are low-growing, keeping close to the source of moisture and out of the drying wind.

• Plant names: A plant's botanical or Latin name will frequently indicate drought-tolerance. Plant names that include terms like tomentosum, pubescens, villosus, mollis, hirsuta, hirta or hispida indicate hairy leaves or stiff hairs on stems and leaves while the term glauca indicates a white or grey bloom on leaves.

For further information and lists of drought-tolerant shrubs, perennials and annuals, please see the Toronto Master Gardeners fact sheets on these topics on the Toronto Botanical Garden's website at www.questions.torontomastergardeners.ca.

General Care and Maintenance

Lawns

• Mow high, keeping the lawn at 3”. Mow frequently, so that you do not remove more than 1/3 of the grass length and leave the clippings on the lawn to provide a natural mulch and return nutrients to the soil.
• Aerate and dethatch to encourage water penetration deep into the soil.
• Apply compost and overseed with an appropriate seed mix to keep the lawn lush and to help choke out weeds.
• Mow late in the day when the grass is dry and use a sharp mower blade.
• Apply phosphorous in the spring to promote root development and nitrogen in late fall - 3-4 weeks before the soil freezes.

Mixed plantings of trees, shrubs and perennials

• Regular weeding will remove competition for moisture and nutrients.
• Pruning can keep your plants vigorous and reduce their demand for water by removing excess growth.
• Deadheading perennials will keep them looking more attractive, discourage self-sown seedlings and encourage the plant to produce more flowers.
• Avoid using many chemical fertilizers: they do not benefit the soil and can cause a lush growth that reduces a plant's drought tolerance.

Organic Management/Control Strategies

The City of Toronto adopted a new municipal by-law (spring 2004) that restricts the use of pesticides. For details about the by-law visit the Pesticide by-law page on Toronto Public Health's Web site at www.toronto.ca/pesticides or www.toronto.ca/health. Questions may be e-mailed to pesticide@toronto.ca. For tips on water efficiency, call 416-397-LAWN or visit www.toronto.ca/water.

The City of Toronto in partnership with the Toronto Master Gardeners has developed an excellent series of fact sheets on organic gardening and control strategies. These can be found on the City of Toronto's website at www.toronto.ca/pesticides or on the Toronto Botanical Garden's website at www.questions.torontomastergardeners.ca.

References

The Toronto Botanical Garden Weston Family Library is an excellent source for horticultural information.

Books

• Bennett, Jennifer. Dryland Gardening. Willowdale, Toronto: Firefly Books, 2005.
• Chatto, Beth. Beth Chatto's Gravel Garden. London: Viking, 2000.
• Chatto, Beth. The Dry Garden. London: Dent & Sons, 1978.
• Phillips, Roger and Martyn Rix. Perennials. Willowdale: Firefly Books, 2002.
• Phillips, Roger and Martyn Rix. The Random House Book of Bulbs. New York: Random House, 1989.
• Phillips, Roger and Martyn Rix. The Random House Book of Shrubs. New York: Random House, 1989.
• Taylor's Guide to Water-saving Gardening. New York : Houghton Mifflin,1990.

Other resources:

Mason Hogue Gardens: 3520 Durham Rd. #1, R.R. #4 Uxbridge, ON. www.masonhogue.com. A xeriscape demonstration garden and a good source for drought tolerant plants.

Factsheets are produced by the Toronto Master Gardeners in association with the Toronto Botanical Garden. They provide introductory information about a broad range of horticultural topics and are intended for personal use and study purposes. Should your gardening group or organization wish to use multiple copies we ask that you inform the Toronto Botanical Garden at info@torontobotanicalgarden.ca.

Date revised: November 18, 2007