Van Leeuwen Green: the water saving specialists.

Our general philosophy is that gardens can still be relatively green and even lush in parts and still use sustainably small quantities of water. While expensive hardware such as tanks and grey water systems have become popular and are in some cases a good idea, we begin with a different approach. We believe that in many cases, the benefits of money spent on this infrastructure are limited. Instead, the money saved is better invested in the plantings themselves: in quality stock, proper establishment, appropriate species selection, and expert design and maintenance.

How we do it

Good horticultural practices, products and maintenance

Water use can be reduced simply through good horticultural practice such as application of mulch, soil wetting agents and building up the levels of sponge-like organic matter in soils. Weeds use as much water as desirable plants, so these must be kept suppressed.

Plant hydro-zoning

We design gardens based on three zones: the zero irrigation zone, the minimum irrigation zone and the full irrigation zone.

Zero irrigation areas are parts of the garden planted with drought tolerant species, which might include carefully selected native or other arid zone plants. Areas of the garden suitable for this treatment are exposed west facing garden beds or dry, shady areas.

The minimum irrigation zone includes plants that are drought tolerant but need occasional watering to maintain a high quality appearance. Examples include viburnums and plumbago. Other plants in this zone have lush green foliage but which are relatively conservative in their water use. Camellias are a good example- beautiful dark green foliage, wonderful flowers but they are not greedy when it comes to water: they simply need a minimal amount to keep them ticking over, even during a drought.

Highly visible or high use areas such as those outside of living room windows or around entertainment areas are perfect for a more lush look using a standard drip irrigation regime. Here we can include some luxury plants such as japanese maples, silver birch and similar less hardy species.

Separation of root zones

Above-ground segregation of species with different water requirements can fail as a strategy if what is going on below the ground is ignored. Tree roots can spread laterally from their trunk as much as twice the distance as the height of the tree. This means that a large thirsty tree can invade all areas of the garden, robbing lush zones of their water and even causing the death of otherwise drought tolerant plants which cannot compete with a large tree despite their overall biological toughness. To overcome this, simple subterranean plastic root barriers are installed between zones.

Species selection

Appropriate species selection is obviously a key method of ensuring that gardens use less water and survive droughts. But species selection for drought tolerance is often applied in a rather simplistic way. Van Leeuwen Green prides itself on its sophisticated approach to species selection in order to address the following issues:

• Not all natives are drought tolerant
  For example, some native plants come from moist, high rainfall environments in places like the Dandenong Ranges. They are not therefore suited to all garden situations.
  
  
• Many drought tolerant plants still use a lot of water
  One way that plants survive drought is simply through aggressive expansion of their rootzone, and an ability to outcompete other plants by effectively stealing all the water from other plants around them. Some species of eucalyptus and conifers are good examples. Thus while these species can be useful in designing drought tolerant gardens, care must be taken in their placement in relation to other plants.
  
  
• Some lush-looking plants are actually very drought tolerant or conservative water users
  Some plants are particularly good at surviving drought by simply “shutting up shop” and resting during dry times. Others are naturally relatively slow growing and as a result tend to be conservative in their water use. Camellias are a good example, as are the small native Brachychiton trees that include the Illawarra Flame Tree. Perhaps the best example of all is Clivea miniata, with its lush dark green leaves and bright orange flowers - it survives droughts in shady spots with zero irrigation
  
  
• Species selected should be long lived
  The problem with short-lived species is that they need regular replacement. This is costly financially as well as environmentally. Not only do new plants need extra watering to get them established but the production of nursery stock uses up very large quantities of water (not to mention the large carbon footprint that comes from greenhouses, the plastic in the pot and the fertilisers). This is a key design criteria that is frequently overlooked. Unfortunately many drought tolerant native and Mediterranean plants are rather short lived, and we tend to avoid using these species.
  
  

Efficient Drip Irrigation Systems

Drip irrigation has become the standard low cost and effective way to apply water to plants. The driplines are placed beneath mulch so that evaporation is negligible, and water reaches plant roots directly.

Use of hard surfaces and passive water harvesting

By increasing the area of hard surfaces such as paving for entertainment areas, the area of garden is reduced. If this is done with careful design, the garden need not lose any of its overall sense of green abundance. Hard surface areas also catch water, and if correctly shaped and with appropriately designed garden beds, the water can simply be directed onto the garden.