What is a weed?

Simply, a weed is defined as a plant growing where you don't want it. However, in reality it is a bit more complicated than that.

In NSW there are many other definitions for weeds too. You may have heard of environmental weeds, agricultural weeds, Weeds of National Significance (WoNS) and National Environmental Alert List weeds

These are all different classifications of weeds and interestingly some weeds can be several of these classifications. For instance, serrated tussock is a WoNS and a serious agricultural weed in some parts of NSW. Similarly, alligator weed is a WoNS, an environmental weed and is now emerging as an agricultural weed as well.

You can check what weeds are in your area and how they need to be managed using the NSW WeedWise database.

How do I know if a garden plant is weedy?

Some plants can be weedy in some areas and not others. There are many common garden plants that fit this description (e.g. morning glory and agapanthus). For example a harmless garden plant from inland NSW may become weedy if grown in a garden on the coast. Therefore, care must be taken when bringing plants home to your garden from other areas.

Don't be fooled into thinking that native plants are always a safe option. They can also become weeds when they are grown in areas out of their original environment. A classic example of this is the Cootamundra wattle (Acacia baileyana) which has proven invasive outside of its natural region.

Even popular edible species of plants that are often grown in gardens like olives and passionfruit have become weeds in some areas. They need to be carefully managed to reduce the risk of becoming a weed problem elsewhere.

Generally, a plant has the ability to become weedy if they have any of the following traits:

  • The ability to spread by vegetative means (e.g. bulbs, roots or stem fragments)
  • Produce berries that can be eaten by birds (e.g. olives, camphor laurel)
  • Produce large amounts of seeds
  • The ability to survive under extreme conditions
  • A history of weediness in similar climates.

View Information on how to stop the spread of weeds or ask an expert for advice.

Further information on weedy garden plants and a tool to help you identify a range of weeds can be found at Weeds in Australia.