Introduction

Waltraud Pix is an entomologist with a passion for the environment.  She has created a lyrical front garden in a Hackett suburban street doing away with lawn and conventional pretties instead trialling plants useful for revegetation on nearby Mt Majura. The garden creates a striking contrast to the surrounding conventional suburban front gardens.

You are just as likely to find Pix working in her front garden or weeding Horehound from a former sheep campsite on Mt Majura – she is the voluntary coordinator of the Friends of Mt Majura. 

Converting the nature strip

Her nature strip has been transformed from a compacted weedy area to a diverse and fascinating landscape.  Pix, a German native, has grown a mix of native grasses and forbs (herbaceous non-woody wildflowers) in her front garden.  Species include local native grasses such as Themeda triandra (Kangaroo Grass), Austrodanthonia (Wallaby Grass), Austrostipa (Spear Grass) and Poa (Snow or Tussock Grass).  Forbs include the beautiful Wahlenbergia (Bluebells), the ACT’s floral emblem; Chrysocephalum semiapossum (Clustered Everlasting); Leucochrysum albicans (Hoary Sunray), Vittadina (New Holland Daisy) and the Black-Anthered Flax Lily, Dianella revoluta. 

Prior to planting, the heavily compacted soil was loosened with hand tools.  Plants were established in two ways – by broadcasting seed as well as planting small plants.  These plants have formed a dense cover over the former exotic nature strip.  The native grasses have begun to dominate, out-competing smaller species.  An Acacia rubida (Red Stemmed Wattle) has self sown into the mix and she has planted a number of Acacia dealbata (Silver Wattle)which have grown rapidly.  As these wattles grow they will cast shade changing the understorey composition.

For a List of Native Grasses and Forbs suitable suitable for use in Canberra gardens refer to the list compiled by Yarralumla nursery.

Maintenance

Ideally this native grassland should be mulched once a year with a product such as ‘Forest Litter’ to a depth of 75mm.  (However, Pix recommends leaving a few areas bare, such as between stepping stones if you wish to encurage ground nesting insects).   Mulching inhibits weeds which may become tall and shade out desirable plants, reduces moisture loss and provides habitat for ground dwelling invertebrates.  Any weeds, particularly those with seed heads or in flower, should be removed by hand to prevent further weeds germinating.  Fertiliser such as Dynamic Lifter may be applied lightly in Spring and Autumn at a rate of 50kg per 250 square metres.  Most native species will survive on natural rainfall, however with present persistent drought conditions new plant and seeds will require regular watering to ensure germination and growth.  It’s important to check the soil depth under the mulch to see how far water has penetrated before applying further irrigation.  Gaps within the plant matrix should be filled as the aim is to create a robust ecosystem which should shade out weed species.

Butterflies and Moths
Butterflies are often admired insect visitors to gardens and particularly delight with their striking colours and markings.  Moths are less spectacular than butterflies, emerging at night and attracted to white and cream coloured flowers.  For more information on attracting butterflies to your garden.

>> Image of Common Brown Butterfly.

Native bees
Amazingly Australia has over 1500 species of native bees, however the best known bee is the exotic honey bee, Apis mellifera.  This species was introduced to Australia in 1822. Pix has observed four different native bee species collecting pollen from Dianella, and believes this is an essential species to use in an insect attracting garden. These bees, like both butterflies and hoverflies, frequently visit the native daisies Vittadina (New Holland daisy) and Xerochrysum viscosa (Sticky Everlasing).

There are approximately 25 species of blue-banded bees (Amegilla sp), found throughout the Australian mainland.  They are ground nesting solitary bees which feeds on the nectar from both native and exotic plants.   Blue banded bees make excellent pollinators and have been used in trials pollinating glasshouse tomatoes. They are characterised by iridescent blue stripes on a glossy black abdomen.  Blue-banded bees are attracted to introduced plants like Lavender, Lemon Balm, Tomatoes as well as the native lilies, Dianella which occur locally in the Canberra region.

For more information on native bees.

Ladybirds
There are almost 300 species of ladybirds in Australia, with most having a beneficial role in the garden.  However, the 28 spotted ladybird feeds on tomatoes, pumpkins and potatoes.  The mealybug ladybird, Cryptolaemus montroutizieri is produced commercially and used as an alternative to chemical sprays.  This ladybird was introduced into the Royal Botanic Gardens, Melbourne to control infestations of mealy bugs and is also used at New Parliament House.

Hoverflies
Adult hoverflies feed on nectar and pollen and are important plant pollinators.  Their larvae feed on aphids and other small pests.  They are characterised by body stripes and are often seen hovering in the garden during warm weather.

Praying Mantis
As their name suggests, Praying Mantis are effective garden predators.  The larvae and adults prey on a wide range of moving insects.

>> Image of Praying Mantis

Insects and biological control

There are a huge variety of insects in Australia, many of which have not been described.  Insects have a vital role to play in the garden.  They may play a role in soils aeration, litter decomposition and nutrient recycling while native bees and butterflies assist in plant pollination.  Many native insects such as Wasps, Hoverflies, Praying Mantis, Stick Insects, Dragonflies, Lacewings and Ladybirds prey on other insects.  Hoverflies, Lacewings and Ladybirds all prey on aphids which can be a common insect pest in gardens.

Rather than resorting to using chemicals, a number of landscape managers have introduced predatory bugs into the landscape to control infestations of pest insects.  At New Parliament House, Landscape Services have released two predatory mites (Phytoseilulus persimilis and Typhlodromus occidentalis) to consume the two-spotted mite, a common pest of many plant species.  The native orange and black Lady Beetle, Cryptolaemus montrouzieri is also used to control mealybug and scale, which can be serious pests on both indoor and outdoor plants.

References:
Eddy, David (2001) Grassland flora: a field guide for the Southern Tablelands (NSW & ACT). CSIRO: Canberra.