They had one mission: to rid the area around the Bruce Trail of the Garlic Mustard plant. This aggressive plant competes with other plants for sunlight, water, and soil nutrients. It also prevents other plants’ seeds from germinating by releasing chemicals into the soil. A single Garlic Mustard plant can produce up to 8000 seeds.
That is why removing this invasive species is so important. The volunteers were very successful in their efforts. The Blue Mountains Bruce Trail Club is committed to protecting the biodiversity of our area for future generations.
On May 22, 2025, a group of hardy volunteers including our Conservation Ambassadors, braved the inclement weather to take on a section of the Timpson property which was being taken over by Garlic Mustard plants. There were over a dozen large garbage bags of Garlic Mustard collected and taken away for solarisation; a method of using the sun’s energy to produce high temperatures, which can destroy the weed seeds.
Garlic Mustard is an adaptable, aggressive, biennial (2 year life cycle) herbaceous plant. The first-year plants produce a rosette of dark green, kidney-shaped leaves with scalloped edges:
The second-year plants grow a stem 30-120 cm (11.8-47.2 in) high with triangular, alternate, sharply toothed leaves:
The lower leaves are kidney-shaped and up to 10 cms across and the plants produce white flowers with four small petals in May.
Garlic Mustard plants should be pulled before they go to seed:
Garlic Mustard seed pods. seeds are dropped as these dry out.
The control of Garlic Mustard is very important as it forms dense monocultures that reduce the biodiversity and aesthetic value of natural areas. The effects of Garlic Mustard on ecosystems are long-lasting and may permanently alter forests, even after removal. It releases allelopathic chemicals that change soil chemistry and prevent growth of other plants. It outcompetes and actively displaces native woodland plants.
Within the Blue Mountains Garlic Mustard grows pretty well everywhere and spreads quickly along roadsides, trails, and fence lines. The main pathway for seed spread over long distances is through humans, pets and wildlife inadvertently carrying seeds to new areas on boots, clothing or fur. Hiking trails such as the Bruce are also a major corridor for seed dispersal and the spread of Garlic Mustard plants. It only takes one plant to start a new population.
It will be important to continue with repeated pulling of the same area for at least 5 years to ensure that the seed bank is depleted. If only done once, there is the likelihood of increasing Garlic Mustard densities by stimulating seed germination through soil disturbance.
