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Lesson Content

1. Making Sustainable Choices

   When designing a garden, it is essential to look at landscapes and cities as systems rather than objects. In these systems, you want to look at the functionality of the plants and processes you implement, with nature in mind, rather than solely looking at the aesthetics, which should come second for a sustainable design. In this lesson, we will again refer to the research of Johann Bernhardt and multiple others in their book ‘A DEEPER SHADE OF GREEN’, as well as Elizabeth Wilhide’s ‘ECO’.

2. Working with the Environment

   In ECO, Wilhide discusses the importance of working with nature when designing a garden for not only people, but for the environment. Designing for the environment in mind can provide its own sense of joy for the people who step into a more naturally functional space.

   This means:

   • Planning and designing your landscape with regard to local conditions
   • This includes taking into account the type of soil, the amount of rainfall, the temperature range, and the prevailing winds of the site
   • By choosing plants that naturally tolerate this given set of conditions, the plants will thrive better and less intervention will be required in the form of maintenance and control
   • Overall, make an attempt to replicate the self-sustaining ecosystem of the surrounding area

   

   A natural garden replicating a self-sustaining ecosystem by Second Nature

3. Adding to these ideas, here is a summary of Elizabeth Wilhide’s eco-friendly gardening strategies:

   • Don’t use chemicals, practice companion planting (different plant species supporting each other)
   • Compost organic waste, including: kitchen scraps from home or from food room at school, dead leaves, as well as plant and grass trimmings
   • Use mulch to improve water retention and keep weeds down
   • Encourage birds, butterflies, bees, and other forms of wildlife by planting species that are attractive to them, such as nectar-producing flowers

   

   A well mulched garden is covered with moisture tolerant plants by Foley Group

4. From ‘A DEEPER SHADE OF GREEN’, Blake Cameron discusses xeriscape water saving strategies:

   • A xeriscape is where plants with similar water requirements are grouped together, by planting drought-tolerant lawns, and by using natives
   • As a result, highly efficient drip-type irrigation systems can be used only where necessary

   .

   As explored in lesson 1, there is the great opportunity for rainwater collection for garden irrigation. For example, water could be caught on a roof of an existing building or shelter located within your landscape design, where it could be stored in a tank and dispersed by a drip-type irrigation system to water the garden where necessary, or for a drinking water source after going through a filtration, purification, and pump system (see lesson 1 for more information).

   

   A xeriscape landscape design by Second Nature

5. Reducing the Effects of Runoff

   It is also key to understand that drainage and stormwater management are of particular concern. This is because runoff is the most environmentally damaging effect of urban development, with erosion and pollution of waterways and harbours at severe levels. This is where plant and material selection (see lesson 2 for more on material considerations) are vital.

   You need to think about:

   • Implementing green roofs and roof gardens to absorb rainfall water that would otherwise run into drains
   • When grading or planting, soil should be replaced according to the existing soil profile as it acts like layers of a sandwich: the top layers provide nutrients and the bottom stability (so you need the correct layering or water may be trapped between the layers and the plant will drown)
   • Using materials where you have considered the life-cycle and embodied energy (weighing up between a long life-span and the extensivity of the embodied energy)
   • Particularly, avoid materials containing PVC and ‘tanalised’ treated wood products, especially around fragile ecosystems such as streams and wetlands. Medium Density Polyethylene (MDPE) and mineral timber preservatives are suitable alternatives in most cases
   • Avoid large impermeable concreted areas as these promote the runoff of rainwater into waterways. When paving is necessary, use enviro-pavers, open-graded concrete, permeable asphalt mixes, and grassed paving systems to absorb runoff

   

   Implementing natural systems of ponds and plants can help catch and purify runoff water

6. Sustainable Plant Options

   As discussed above, when choosing plants, you need to have your site’s conditions in mind. Ideally, you want to choose plants native to your country, not exotic plants that come from halfway across the world, although as beautiful they may be. You should think about how sustainable they are, including their care requirements and water consumption, and where they would work best. Further resources can be found below in the ‘SUPERSIZE ME’ section.

   

   Tree pits in Auckland

7. Here are a few native New Zealand species that are quite resistant to dry conditions according to (“NZ Native Plants & Trees - Native Flowers, Shrubs & Plants» archipro.co.nz,” 2020):

   1. Astelia Chathamica

   Astelia Chathamica has broad spiky silvery green leaves which droop at their tips, and orange berries from Feb-June which attract birds. 

   • Temperature: Not hardy

   • Light: Sun/Semi shade
   • Moisture: Well drained (rich soil)
   • Wind tolerance: Medium

   

   Astelia Chathamica

8. 2. Carex Testacea

   Carex Testacea is a NZ native orange and green sedge grass. It is densely tufted with fine narrow arching leaves and lasts all year round. It grows to approximately 60cm x 60xm when mature.

   • Temperature: Hardy
   • Light: Full sun
   • Moisture: Well drained
   • Wind tolerance: Hardy

   

   Carex Testacea

9. 3. Carex Comans Bronze

   Carex Comans Bronze is another small NZ native sedge grass. It grows up to 30-40cm high, with reddish brown foliage. The small size makes it perfect for smaller landscapes, borders or edges.

   • Temperature: Hardy
   • Light: Full sun
   • Moisture: Well drained
   • Wind tolerance: Hardy

   

   Carex Comans Bronze

10. 4. Chionochloa Flavicans

    Chionochloa Flavicans have flowing green foliage and weeping flower-heads in summer. The arching flower stems are up to 1.5m long and carry drooping plumes of a silky pale green. It grows to approximately 1.5m x 1.5m when mature.

    • Temperature: Hardy
    • Light: Sun/Semi shade
    • Moisture: Well drained
    • Wind tolerance: Hardy

    

    Chionochloa Flavicans

11. 5. Corokia Geenty’s Green

    Corokia Geenty’s Green is a shrub covered in early summer with star shaped yellow flowers followed by orange berries in late summer. Corokia is great for a formal dense hedge when clipped, where it can grow to 2m but can be easily trimmed to 75cm to 1m.

    • Temperature: Hardy

    • Light: Sun/Semi shade
    • Moisture: Well drained
    • Wind tolerance: Hardy

    

    Corokia Geenty’s Green

12. Here are a few native New Zealand species that are quite resistant to wet conditions according to (“NZ Native Plants & Trees - Native Flowers, Shrubs & Plants» archipro.co.nz,” 2020):

    1. Coprosma Virescens

    Coprosma Virescens is an upright shrub or small tree with thin, pale-green leaves on divaricating stems. It is good for riparian or reveg projects, or as an informal hedge. It grows to approximately 3m tall x 1m wide when mature.

    • Temperature: Hardy
    • Light: Medium
    • Moisture: Wet
    • Wind tolerance: High

    

    Coprosma Virescens

13. 2. Carex Frosted Curls

    Carex Frosted Curls is a hybrid variety of the NZ native sedge. It has pale green grasslike leaves that curl towards the ground, softening any landscape. It makes a great border, or they can be grouped together for ground coverage. It grows to approximately 40cm x 40cm.

    • Temperature: Hardy
    • Light: Full sun
    • Moisture: Hardy
    • Wind tolerance: Hardy

    

    Carex Frosted Curls

14. 3. Pseudopanax

    The Pseudopanax Arboreus is a small tree that has deep shiny green leaves, and tiny flowers in winter followed by small berries that attract birds. It grows to approximately 6m high by 3.5m wide when mature.

    • Temperature: Hardy
    • Light: Sun/semi shade
    • Moisture: Hardy
    • Wind tolerance: Medium

    

    Pseudopanax

15. 4. Phormium Evening Glow - Flax

    Phormium Evening Glow is a flax selected cultivar. It was chosen for its bold, variegated burgundy red foliage, which intensifies in winter. It looks great by itself or in mass plantings. It grows to approximately 1m x 1m when mature.

    • Temperature: Hardy
    • Light: Full sun, but will tolerate part shade
    • Moisture: Hardy
    • Wind tolerance: High

    

    Phormium Evening Glow - Flax

16. 5. Phormium Jack Spratt - Flax

    Phormium Jack Spratt is a dwarf flax with narrow upright bronze-red leaves. It looks particularly good when group planted. It is great in containers and rock gardens. It grows to approximately 30cm x 30cm when mature.

    • Temperature: Hardy
    • Light: Full sun, but will tolerate part shade
    • Moisture: Hardy
    • Wind tolerance: High

    

    Phormium Jack Spratt - Flax

Citations