Trending – Australian landscapes in the early twenty-first century packed with hardy native plants showing off our unique and diverse ecology. Yet, it’s always fashionable to ‘mix and match’ – mixing natives with exotics, widening the planting list to include species from around the world.
Whilst Australian plants can be quite unique at species level, we share a lot of common families with plants from across the oceans. The trick remains in matching ‘exotic’ plants that have similar growing conditions in their homelands to those of the landscape site.
So, as the availability of exotic cultivars continues to rise, it’s always worth a look at what’s available – new plants bred to provide solutions to landscaping challenges in a changing world.
Screening
In the hedging section of any nursery there’s a plethora of shrubs with names like, Dense Fence, Privacy or Green Pillar. It seems that as the space between neighbours continues to diminish, the demand for screening plants continues to rise.
Murraya ‘Sweet Privacy’
Murraya hedges have invaded the suburbs of Sydney and Melbourne. Its dense, rapid growth make it ideal for screening. Seedling forms of Murraya paniculata have been classified as an invasive weed in parts of NSW and Queensland so it’s important to source cultivars, like ‘Sweet Privacy’ that produce little or no fruit.
An unusual problem with Murraya has been its rapid growth leading to excessive maintenance costs. ‘Sweet Privacy’ grows to a maximum height of 2.5m by 1.5m and requires trimming only two to three times per year. There are a number of Murraya cultivars on the market so make sure the plant matches the site’s requirements – Murraya ‘Min a Min’, for example, is a dwarf form growing to only 1m.
Full sun to part shade, but remember Murrayas are in the citrus family and will need at least one application of a controlled release fertiliser coming into spring. Try to avoid trimming back in the depths of a cold winter as the plants will just sit there and drop leaves around the cuts – maintenance contractors call it the “sulks”.
Viburnum Odoratissimum ‘Dense Fence’ ‘Quick Fence’
These cultivars of ‘sweet viburnum’ can be grown as far north as Brisbane but may be a better choice than Murraya for cooler Melbourne, Tasmania and the highlands.
‘Dense Fence’ with its finer leaves, grows into a dense hedge up to 3.5m tall by 2m wide and requires less pruning than the common form. ‘Quick Fence’ (4m by 2.5m) grows quicker and requires more pruning due to its faster growth rate. Full sun to part shade but the period for guaranteeing water during establishment should be at least eight weeks.
Camellia sasanqua ‘Paradise’ cultivars It’s hard to go past Camellias for clients who require both privacy and a bit of seasonal colour. Paradise camellias are hybrid camellias bred in Australia for Australian conditions growing from Tasmania right up to subtropical Queensland. Generally, hybrid sasanqua camellias will take more sun than their larger leafed relatives – the japonicas.
They make a dense deep green hedge that can be pruned to 1.5m or reach up to 4m. These long-lived, drought hardy plants flower from late summer into winter attracting nectar-eating birds and beneficial insects.
Ground Cover Shrubs
Small shrubs planted at tight centres remain a great ground cover alternative to grasses planted en masse. Shrubs will completely cover and shade out weeds with the added bonus of swathes of seasonal flower colour.
Rhaphiolepis Indica ‘Cosmic White’ ‘Cosmic Pink’
Rhaphiolepsis indica, commonly known as ‘Indian hawthorn’, has always been bullet-proof landscape stock. Tolerating a range of climates and soils as well as frost, drought and coastal conditions. These small shrubs flower heavily in spring and spot flower throughout the rest of the year producing a fleshy fruit eagerly consumed by birds. This tasty fruit with highly viable seed has led to Indian hawthorn invading the bush particularly around Sydney and South-East Queensland.
Enter the plant breeders – Rhaphiolepsis ‘Cosmic White’ and ‘Cosmic Pink’ have been bred to have very low seed set and viability making these cultivars the environmentally responsible choice. The white form grows to 1.5-2m by 1.5m but responds well to trimming while ‘Cosmic Pink’ is more compact (0.5 – 0.8 x 0.5 – 0.8).
‘Encore Azaleas’ ‘Autumn Royalty’ ‘Autumn Twist’
Older landscaped gardens often used swathes of azaleas to provide visual impact with masses of white, purple, pink, orange or red flowers. These heat/cold tolerant and relatively drought hardy shrubs have decreased in popularity over the years as azalea lace bug attacks left them looking sickly and requiring ongoing maintenance.
Sap sucking lace bugs congregate on the underside of the leaves sucking small sections of the leaf dry before moving on, leaving the plant with a silvery, desiccated look. The quickest maintenance solution has been to spray with a systemic insecticide usually containing the active constituent, imidacloprid. Yet, with the bad press these neonicotinoid sprays have been receiving around their possible effects on bee populations, wouldn’t it be great if we could breed a lace bug resistant azalea.
Azalea ‘Autumn Royalty’ and ‘Autumn Twist’ have proved their resistance to lace bugs in trials published in HortScience and although I have to admit I was a little dubious when planting a hundred or so… it’s true!
Alternanthera dentata ‘Little Ruby’ Alternanthera dentata could become a little scraggly. ‘Little Ruby’ is a more compact form growing to 0.4m high and spreading to 0.9m. A great ground cover for areas of high humidity, it is also moderately frost tolerant. Its deep burgundy foliage is a real stand out and looks great contrasted with other spreading ground covers. Try contrasting it with the grey/silvery leaves of the ‘liquorice plant’ (Helichrysum petiolare).
Small Trees
It’s difficult to get clients to accept trees into the landscape with media reports around toppling eucalypts as well as Council Tree Preservation Orders that actually scare homeowners into not planting trees fearing a lack of control in any future trimming or removal. This consumer hesitation has led to the breeding of a number of smaller trees suitable for urban landscaping.
Lagerstroemia indica ‘Indian Summer’ The ‘Indian Summer’ range has been bred to resist the scourge of crepe myrtles – powdery mildew. Suitable for tight spaces, they range from 3m to 8m in height. Deciduous, showing off their coloured trunks in winter followed by white, pink or lavender flowers in summer, crepe myrtles really tell the story of the seasons!
Magnolia Grandiflora ‘Teddy Bear’
This Magnolia cultivar seems to be winning the popularity stakes over Magnolia ‘Little Gem’. ‘Teddy Bear’ has a more compact, dense form (4m x 3m) with the same stunning creamy white, saucer-shaped flowers
Natives versus exotics, after all, a native from Western Australia is as alien to Queensland as ‘Indian hawthorn’. The trick remains in selecting exotic plants that are suited to the growing conditions of the site and, most importantly, are non-invasive.
Stock availability is always in a state of constant change making plant selection a process of mixing and matching, where the popularity of a particular plant falls apart only to be replaced by a new, improved variety – stay up to date and ahead of the pack!