You may have heard the saying “a weed is just a plant in a place it isn’t wanted”. This is a concise definition of how a gardener views weeds. From an ecological standpoint different plants can have different weediness potential. A plant is considered to have weed potential if it spreads easily and quickly, it has negative impact on the area it spreads through, it is hard to control when established, or a combination of these factors.

Taming the weed species -Sterile and low-seed cultivars

There are garden plants that have been bred to avoid weediness. The original plant may have been very invasive but the plant breeder will have selected for less invasive individuals, usually by choosing sterile or nearly-sterile plants that set little to no seed. An example we have here at Nillumbik Nursery is Gazania ‘Double Gold.’ Gazanias usually set lots of seed and are very hardy, so they can easily escape from gardens and become a weed in the surrounding area. The Double Gold cultivar is sterile, it won’t set seeds. This means that you still get a resilient garden plant, but no wandering seedlings. There are cultivars of other plants that are not completely sterile, but the seed set is so low they are no longer considered invasive. Buddleia, a plant sometimes known as ‘Butterfly bush’ is usually very weedy, setting huge numbers of small seeds that spread the plant quickly through the surrounding area. There are varieties of Buddleia that set less than 3% of the usual amount of seed, and these are the ones we choose to stock.

Choosing plants – Is native best?

When choosing which plants to stock, we try to avoid plants that have high weed potential, even though some are well loved garden plants. You won’t see Willow trees for sale here, or Agapanthus. We stock a range of both Australian and exotic plants, as well as a range of local indigenous tube stock. Which brings us to another issue. Australian Native doesn’t mean ‘not a weed’. Plants from other parts of the country can become weeds. Certain Acacia species like the Cootamundra wattle are best avoided in Nillumbik shire. This plant is just fine in its natural range in Central New South Wales, but it isn’t suitable for planting near bushland in Victoria as it can quickly spread. Choosing native plants can be a little confusing, but generally we will use ‘Native Plant’ to mean the plant is Australian, and ‘Indigenous’ or ‘Local Native’ to mean the plant is from North-East Melbourne and the surrounding area.