Why your beautiful garden might be a threat to local biodiversity

Gardening · Published 7 October 2026 Swipe more like this →

In short: In Australia, weeds are a primary driver of biodiversity loss. Remarkably, about 65% of the country's exotic weedy species began their lives as ornamental garden plants. By selecting the wrong species, gardeners can inadvertently create a reservoir for future environmental invaders that displace native life.

Environmental weeds pose a multifaceted threat to Australian ecosystems. They do more than just occupy space; they compete with indigenous flora for vital nutrients, water, and sunlight. Furthermore, these invaders can degrade essential habitats for native animals, harbor dangerous pests and diseases, and increase fuel loads that contribute to bushfires.

The challenge for gardeners is that some weeds are actually exotic species that were originally introduced for their beauty. For instance, the Dietes, a hardy plant from Southern Africa with white or yellow flowers, is a common weed because its seeds spread with ease. Similarly, the Agave Americana, a massive succulent known for its tall flower spikes, spreads aggressively through hundreds of offsets called 'pups'.

Even plants considered native can become weeds if they are grown outside their natural range. A prime illustration of this occurs with the Sydney golden wattle (Acacia longifolia). Even more complex is the Jam wattle (Acacia acuminata); while it is a desirable small tree in Western Australian gardens, it is classified as a weed in parts of Eastern Australia.

To protect local ecosystems, gardeners can swap invasive species for functional natives. For example, replacing a weed with the Kangaroo Paw (Anigozanthos) provides vibrant color through cultivars like 'Bush Elegance' or 'Bush Pearl'. Alternatively, the Balga or grass tree (Xanthorrhoea preissii) offers striking foliage and tall flower spikes that support local wildlife, such as cockatoos and honeyeaters.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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