This is the perfect time of year to tackle our first invasive foe of the season: Garlic Mustard (Alliaria petiolata). If you’re gazing out the window along the Transitway or parkways, you can’t miss this white-flowered plant standing out from the grass or other herbaceous plants around it. Rarely does one plant grow alone, so also noteworthy is its nature of having one tall plant in the middle surrounded by many of its smaller brethren (or children!) This group growth form is due to the way Garlic Mustard produces many seeds, which it then releases in the same location.
Garlic Mustard is a shade-tolerant biennial plant that thrives in woodland settings. It is considered a serious invasive pest of natural areas, particularly woodlands, displacing native flora and severely reducing species diversity. Its aggressive, rapid growth allows it to form dense carpets that prohibit growth of other species.
Recent research shows that Garlic Mustard can release chemicals that destroy the mycorrhizal fungi that many trees depend on for nutrients. This allelopathy means that when Garlic Mustard invades a site, growth of tree seedlings is reduced. Maple trees are particularly susceptible. Like many non-native plants, Garlic Mustard has few natural enemies to help keep it in check.
This is where you come in – Garlic Mustard is one of the easiest plants to pull from the ground, making quick work to clear an area. The fact that thousands of seed are produced means it will grow back, so returning to the same spot is necessary even if you catch a plant before it sets seed this year.
At the FWG, our control strategy is based on the fact that this plant is a biennial, so preventing seed production should eventually eliminate it. We spend several weeks in May pulling out plants that are blooming. During the summer, our volunteers monitor the various patches for later blooming plants and any others that we missed in spring.
Garlic Mustard can also be made into a pesto with a garlicky taste – this is where the ‘garlic’ in its name comes from. The younger the plant the better the flavour, as older plants can be a bit bitter. Just Google a recipe to meet your taste preference! Originally imported in the 1800s as a salad green, this is one garden escapee that needs to be caught.
Why not get your greencercise and spend a few hours pulling the stuff? You’ll find it in any naturalised area – perhaps even in local flower beds. Remember to bring garbage bags for proper disposal – seeds can continue to ripen even on pulled plants, so make sure your hard work stays finished!