Module 1: Waterwise Plant Selection

Introduction to Water-Efficient Landscaping

The Importance of Greenlife in a Drying Climate

In the face of a drying climate, the role of green life—trees, shrubs, and other vegetation—becomes increasingly vital, especially in home gardens and urban landscapes. These green elements are more than just aesthetic features; they are integral to the urban fabric, offering numerous social, economic, and environmental benefits. The Government’s climate change response recognizes green life as a critical tool in mitigating the urban heat island effect, which is the increased temperature in urban areas compared to their rural surroundings.

Environmental and Social Benefits

The environmental benefits of maintaining and increasing plant life are extensive. Trees and vegetation help cool urban areas by providing shade, reducing the need for artificial cooling, and absorbing carbon dioxide, thus lowering greenhouse gas concentrations. Additionally, they play a significant role in reducing salinity and erosion, stabilizing soils, and filtering pollutants from the air and water. Plants also reduce water evaporation by decreasing exposed soil areas and assist in the passive heating and cooling of homes, leading to greater energy efficiency.

Moreover, green spaces improve air quality, promote mental well-being, and support biodiversity by creating habitats for various species and encouraging the formation of micro-climates. They also filter stormwater runoff, reduce noise pollution, and enhance the social fabric of communities by offering spaces for recreation and relaxation. In short, greenlife not only beautifies our environment but also contributes to a healthier, more resilient ecosystem.

Planning for the Future

As the impacts of climate change intensify, with expected decreases in annual rainfall and increases in temperature, planning for greener neighbourhoods with more tree canopy and green spaces becomes crucial. The anticipated reductions in water availability mean that less soil moisture will be available for plant growth, and groundwater recharge and runoff into dams will decrease even more significantly than the drop in rainfall. These changes will challenge horticulture and home gardening, as the cost and availability of water become more pressing concerns.

The loss of trees due to land clearing, bushfires, deforestation, and drought has also had observable impacts on reducing rainfall. Redressing this through re-vegetation and incorporating trees into landscapes is essential for restoring ecological balance and supporting sustainable water cycles.

Given Western Australia’s drying climate and projected population growth, the selection of waterwise plants and water-efficient design are crucial elements in all landscaping projects. As the region faces increased pressure to accommodate rapid population growth, the need for urban infill is resulting in higher residential density and an increase in hard surfaces, reducing the availability of planted areas. This shift underscores the importance of thoughtful urban planning that prioritizes green spaces, not only to enhance liveability but also to mitigate the environmental challenges posed by a changing climate

Adapting to Change

To adapt to these conditions, home gardeners and landscape managers must adopt more efficient irrigation practices and choose drought-tolerant plants that require less water. In regions where water costs are rising, it might be necessary to reconsider plant choices or garden design to improve the financial and environmental return on water use. While new and expanding irrigation areas in the north of Western Australia might not face the same water scarcity issues, the temperature increases in these regions are expected to be more pronounced, further highlighting the need for resilient, water-efficient landscaping practices.

In conclusion, as climate change progresses, the importance of integrating greenlife into our homes and urban landscapes cannot be overstated. By doing so, we not only enhance the beauty and functionality of our surroundings but also contribute to a healthier, more sustainable environment. Maintaining and increasing plant volumes, especially by incorporating a diverse range of species, is crucial for fostering biodiversity and creating resilient landscapes that can withstand the challenges of a changing climate.

Key Components of Water-Efficient Landscaping

Creating a waterwise garden hinges on two main factors: plant selection and design. Achieving a balance between plants, lawns, and hardscapes like paving is essential to creating a space that fits the resident's lifestyle while minimizing water usage.

Waterwise Plant Selection

Choosing plants suited to local soil and climate conditions is essential for reducing water usage in the garden. Resources such as Water Corporation’s guide on waterwise plant selection and the Australian Native Plants Society website provide valuable insights into selecting the right plants. In the following sections, we will explore plant selection in more detail, focusing on options for challenging sites and various garden themes, including Coastal, Mediterranean, Native, Tropical, and Cottage gardens.

Western Australian nurseries, with their extensive experience in drought-tolerant plants, are excellent resources. Local knowledge is vital, as selecting plants appropriate for WA conditions is crucial. The general rule is to prefer drought-tolerant plants over water-demanding ones. If high water use plants are necessary, limit their use to focal points or protected areas. Avoid using bedding plants that require frequent replacement unless they are seasonal varieties established with winter rains, like Everlastings.

Hydro-zoning

To optimize water use, group plants with similar water needs into hydro-zones. This approach allows you to tailor irrigation and prioritize maintenance and fertilizing effectively. Consider the following zones:

• Primary: High water demand areas, such as vegetable gardens, requiring daily hand watering.
• Secondary: Moderate water demand areas, thriving on a two-day-a-week watering schedule, including turf, fruit trees and ornamentals.
• Minimal: Low water demand areas, needing occasional hand watering during hotter months, such as established natives.

Watch this video on Planting in Hydrozones!

Planting Design Guidelines

When designing a water-efficient garden, it's crucial to select plants that are well-suited to the specific site conditions. Here are some key guidelines to help you make the most informed choices:

1. Choose Plants Suited to the Site

Identify and select species that match the site's soil type, pH, and micro-climatic conditions. This ensures the plants have the best chance of survival while reducing watering needs. Local knowledge is invaluable; plant performance can vary widely depending on the climate. For instance, a plant labelled as suitable for full sun might struggle in Perth's intense summer heat. When in doubt, consult local nurseries, horticultural consultants, or refer to the Water Corporation Waterwise Plants database.

2. Use Deep-Rooted Species

Deep-rooted plants, large shrubs, and trees should form the backbone of any planting scheme. These species are typically more waterwise once established, significantly reducing water use over time. Retaining healthy existing trees is also beneficial, as the cost and water required to establish new trees can be substantial.

3. Wind and Sun Protection

Strategically using trees for shade can lower soil and ambient temperatures, providing essential protection for smaller plants and aiding in the passive solar control of buildings. Deciduous trees, like Gleditsia, are particularly useful as they allow winter sun to penetrate while providing summer shade. Evergreen trees should be placed carefully to avoid casting shade on living areas during winter. Additionally, planting trees and shrubs as windbreaks can protect plants from hot, dry winds, reducing water stress and usage.

4. Consider the Scale of the Project

Water-efficient choices should be tailored to the project's scale and budget. For large landscapes, prioritize trees, drought-tolerant ground covers, and hardy native grasses. Lawn areas should be kept to functional uses, with other spaces filled with hardy ground covers or alternative surfaces, complemented by shading from trees or structures.

5. Dry Landscaping

Dry landscaping, or xeriscaping, can be achieved using plants that require no ongoing water once established. Native plants, cacti, succulents, and hardy Mediterranean varieties are ideal for this approach. In the southwest, these landscapes are best established in autumn or early winter to capitalize on the brief wet season. If irrigation during the first summer is not possible, some plant losses may occur, though providing water for the first summer is recommended for optimal results.

6. Avoid Weed Species

Some exotic plants and interstate native plants, although drought-tolerant, can become invasive. Avoid selecting species with weed potential, as these can threaten bushland and cultivated areas, leading to costly eradication efforts. For further information, visit Florabase.

7. The Small Garden Myth

A University of Sydney study suggests that small gardens may not be as waterwise as commonly believed. The research found that small gardens often receive four times more water per square meter than larger ones, partly due to a lack of understanding of plants' water needs. This perception, coupled with the idea that small gardens can be watered more intensively, leads to significant water overuse across many small garden spaces.

8. Plant Selection

Commercial nurseries have historically supplied plants suitable for a twice-weekly watering regime, but with the increasing promotion of waterwise practices, there has been a shift towards more drought-tolerant varieties. The availability and marketing of waterwise plants have grown significantly. For comprehensive advice and information on waterwise plant selection, refer to the Water Corporation's guide, which includes a useful search function for "Waterwise Plants for WA."

8. Plant Selection

Commercial nurseries have historically supplied plants suitable for a twice-weekly watering regime, but with the increasing promotion of waterwise practices, there has been a shift towards more drought-tolerant varieties. The availability and marketing of waterwise plants have grown significantly. For comprehensive advice and information on waterwise plant selection, refer to the Water Corporation's guide, which includes a useful search function for "Waterwise Plants for WA."

Native Plant Misconceptions

There's a common perception that all Australian native plants are drought-tolerant, but this isn't always the case. The adaptability of native plants to hot, dry summers depends on their origin. For example, plants from Queensland or Tasmanian rainforests, as well as some WA temperate understory varieties, may struggle when exposed to full sun and harsh conditions, particularly if they're growing in soil types they're not adapted to.

Local Plants

Local plants are the best choice for your garden as they have naturally adapted to the specific climate and soil conditions of the area. However, it's important to note that plants from different soil types can behave differently when transplanted. For instance, plants from heavier soils may not thrive in sandy soils and may have shorter lifespans, while those from light, free-draining soils might struggle in heavier clay soils. If you're not familiar with the unique requirements of individual species, it's best to stick with local plants to ensure success.

Native Plant Resources

There are several excellent resources available to help with plant selection for different locations:

• "Growing Locals" by Robert Powell: This book is a valuable resource for understanding the benefits of using local plants.
• "Grow Local Plants" Brochures: Prepared by the North Metro Catchment branch of the Phosphorous Action Group, these brochures provide detailed lists of species suited to various locations.
• Specialist Native Nurseries and Waterwise Garden Centres: These are the best places to get expert advice on plant suitability and availability.
• Australian Plants Society (ASGAP) Website: Visit www.asgap.org.au for comprehensive information on Australian plants, compiled by the Association of Societies for Growing Australian Plants.

Design Potential

The design potential of Australian plants is just beginning to be fully realized. Showcases like Kings Park in WA highlight the diverse foliage and habitats of the region’s unique flora, while the Australian Garden at Cranbourne in Victoria demonstrates the incredible possibilities when we draw inspiration from natural landscapes. The range of Australian plants is vast, from the silvery leaves of WA mallees and the intricate designs of Banksia flowers to the lime greens of felty understory shrubs and the textures of reeds and rushes. Exploring and familiarizing yourself with local flora is highly recommended.

Seasonal Colour

One of the most common requests from clients is for "lots of colour" throughout the year. This can be achieved in a native garden by selecting a variety of plants that flower at different times, ensuring year-round interest. Many native nurseries offer catalogues that indicate flowering seasons or provide species lists based on when they bloom. These resources, along with other information on varieties and growing conditions, are invaluable for garden designers.

A particularly useful reference is George Lullfitz’s book "A New Image for West Australian Plants," which categorizes plants by their flowering season, making it easier to plan for continuous colour.

New Varieties

There are many hybrid varieties available that have been bred to flower for longer periods. Significant research has gone into breeding and selecting compact varieties suited for smaller gardens, a necessity as residential blocks decrease in size. In addition to new varieties, it’s worth exploring existing species to find those best suited to specific garden conditions.

Foliage Interest

For added interest and contrast, especially in larger planting schemes, consider the colour and texture of foliage. The native plant palette includes a wide range of greens, silvers, and even burgundy, cream, and gold hues. These can be used to create visual highlights or bands of colour when planted in groups.

Re-vegetation

Whenever possible, it’s ideal to retain natural topography and native species. Re-vegetation with local species can begin with the first autumn rains for best results. Using seed from local provenance is crucial, as it’s adapted to the specific site and will generally perform better than seed sourced from other locations. Re-vegetation can be done via direct seeding or by propagating plants and growing them on before planting out.

For more detailed information, visit the website of the Revegetation Industry Association of WA

Garden Themes and Styles

Included are some examples of waterwise planting options suitable for various garden styles, most of which will thrive with minimal additional irrigation once established. These lists serve as a suggested starting point and are by no means exhaustive. Plants can easily be mixed and matched, allowing for flexibility in design, and many more native plants can be incorporated into these schemes, as they can be adapted to any style.

Verge Gardens

Minimizing lawn areas that are not functional is a crucial water-saving measure, especially in verge gardens. Ground covers can be a great alternative to traditional lawns, offering both visibility and aesthetic appeal. Some ground covers are trafficable and can tolerate more wear, while others act as living mulch, reducing evaporation. These plants can be planted beneath trees and larger shrubs, helping to maintain moisture in the soil and reducing the need for frequent mulching. Here are some recommended options:

Ground Cover Options:

• Adenanthos cuneatus ‘Coral Carpet’ (cultivar of Adenanthos cuneatus)
• Banksia petiolaris, B. blechnifolia
• Dymondia margaretae
• Eremophila (e.g., Eremophila ‘Kalbarri Carpet’; other species include Eremophila debilis and Eremophila nivea)
• Grevillea ‘Gin Gin Gem’, Grevillea poorinda ‘Royal Mantle’, G.  thelmanniana, G. crithmifolia, G. curviloba
• Myoporum parvifolium
• Phyla nodiflora (commonly known as Lippia) – can take light foot traffic

In addition to these spreading, drought-tolerant ground covers, the following plant types are also ideal for verge planting:

Hardy Grasses and Tufting Plants:

These are useful for planting in sweeps or bands across verges:

• Lomandra longifolia, L. hystrix
• Dianella revoluta, D. caerulea, D. tasmanica
• Conostylis candicans, C. aculeata, C. setigera

Small Drought-Tolerant Clumping Plants:

These plants add texture and contrast to your verge:

• Leucophyta brownii
• Banksia nivea

Design Tips for Verges:

With increasing urban sprawl and infill programs, space in newer housing developments is becoming limited, often resulting in reduced verge areas. However, in many older suburbs, substantial verges, sometimes as wide as 5 or 6 meters, remain council property, and householders are responsible for their maintenance. Here are some tips for designing sustainable, low-maintenance verges:

1. Check Council Guidelines: Always start by checking the specific requirements and guidelines from the local council to ensure compliance.
2. Select Low-Growing Varieties: Use low-growing plant varieties closer to the road to maintain visibility and comply with safety regulations.
3. Limit Bulk for Impact: Consider limiting the number of species used and planting them in clusters or sweeps for a more impactful and cohesive design.
4. Consider Parking Needs: If parking on the verge is necessary, plan for permeable surfaces or choose trafficable ground covers to accommodate this.

By choosing low growing, waterwise planting schemes and permeable surfaces, you can create a sustainable and aesthetically pleasing verge garden that conserves water and requires minimal maintenance.

Complete Quiz 1