Resource and information pack on Garden Plants as Environmental and Agricultural Weeds

Roger Spencer,
Royal Botanic Gardens Melbourne, Weed Working Group 
October 2006

"As horticulturists of any persuasion, we have a compelling environmental responsibility not to import, cultivate or promote known or potential weeds."
Geoff Carr, 2002

This resource and information pack has been written for horticulturists and gardeners. It gives an outline of the environmental, economic and social effects of weeds, especially those that have escaped from horticulture, and discusses the present and possible future ways of managing weed impacts.

Download the Resource and information pack (PDF format 627KB).

Weed Strategic Plan 2004 -2008

The Australian National Weeds Strategy of 1999 highlights that weeds are one of the most serious threats to Australia’s natural environment and primary industries. In 2004, it was estimated that weeds cost Australia from  $3.5 billion to $4.5 billion dollars per annum in environmental protection, lost production and control. This does not include the cost of losses to biodiversity by weed invasion of natural habitats or other losses to conservation, recreation and aesthetic values. While the environmental costs are difficult to estimate, it is suggested they are similar or even greater than the costs for agriculture

The vast majority of imported plants into Australia were for ornamental horticulture. Over 1,300 (5%) of these have become agricultural, noxious or environmental weeds, and comprise 70% of all introduced weeds.

The high percentage of ‘garden escapes’ is very significant when it is considered that the 12 major Botanic Gardens in Australia together grow about 40,500 different kinds of plants. This figure is similar to the numbers of commercially available plants, with about 45,000 kinds being available for ornamental horticulture. In comparison, the total of native taxa recorded for Australia is about 16,000.

There is a clear need for Botanic Gardens to consider weed management strategies and the risks of plants ‘escaping’ to damage the natural environment and primary production.

In 2004, the Royal Botanic Gardens Melbourne developed a Weed Strategic Plan to link education opportunities, management requirements and current scientific knowledge to minimise infestations and risk of weed spread both within and outside its managed lands.

For the purposes of the Weed Strategic Plan, weeds are defined as “invasive plants that pose real or potential threats to the conservation of indigenous plant habitats, the sustainability of agricultural industries and horticultural values of managed gardens.”

This Weed Strategic Plan aims to build on current staff commitment and strong support from external agencies to achieve the objectives of the Royal Botanic Gardens Policy for conservation of plant biodiversity: conserving Australia's plants for the future to prevent future spread of weeds, and improve and develop weed management goals.

Download the Weed Strategic Plan (PDF format 194KB).