Australia is a land of enormous geographical and climatic differences. The vast red sand plains and dunes of Western Australia's Great Sandy Desert support only a few heat and drought-tolerant grasses and trees. Queensland's dense, humid rain forests, however, contain more than 1,100 documented plant species. Tropical plants from every one of Australia' regions are now cultivated as hedges in Down Under gardens.
Australia's national floral emblem, golden wattle (Acacia pycnantha) is popular shrub and hedge plant native to the southeastern continent's open forests. Standing from 16 to 25 feet high, golden wattle has curved phyllodes (flat leaf stems) instead of traditional leaves. In late winter and spring, clusters of golden flowers appear at the juncture of the phyllodes and twigs. Started from seed, plants frequently grow quickly enough to flower in their second year. They require well-drained soil and sun to partial shade, but aren't fussy about soil type. In coastal areas, cautions the Australian Native Plants Society, they need protection from salt spray.
Scarlet banksia (Banksia coccinea) is one of about 75 species of evergreen banksias endemic (native nowhere else) to Australia. Banksias, says Gardening Australia, are hedge shrubs or small trees that typically have long, leathery leaves. Scarlet banksia grows wild in the sandy woodlands of Western Australia's southern coast. Normally growing to 13 feet high, it has broad, toothed leaves. Abundant, 4-inch cylindrical spikes of vivid red-orange flowers appear from June to January. Cutting the flowers for use in floral arrangements encourages more bloom and heavier foliage.
Although extremely popular as a garden hedge, scarlet banksia often succumbs to root rot in wet, humid locations, warns the Australian Native Plants Society. This makes it unsuitable as a garden hedge in eastern Australia from Sydney northward. It prefers full sun and exceptionally well-drained, low-phosphorus sandy soil.
Grevillea, says Gardening Australia, are woodland plants of the protea family. Evergreen shrubs or trees, they have foliage varying from needle- to fern-like. Their flowers also vary in form. Some resemble small or large brushes, and others resemble spider chrysanthemum blooms. Juniper-leaf grevillea (Grevillea juniperina) has needle-like foliage up to 1.3 inches long. Grown as a hedge, it can reach 8 feet high. Its spider-form flowers may be greenish-yellow, yellow, pink, apricot, or red. The nectar-rich blossoms are irresistible to birds and insects. Frost-tolerant, juniper-leaf grevillea prefers full sun but accepts light shade and will handle any well-drained soil.