Garlic Mustard

In early spring, flashes of green in the PEI landscape can be welcome reminders that longer days and warmer weather are returning. Unfortunately, they can also be signs of non-native plants with competitive advantages that make them problems.  Today’s plant is the delicious but invasive Garlic Mustard (Alliaria petiolata). 

Photo 1: The first-year basal rosette of Garlic Mustard. This invasive species appears in early spring, before native plants have started to green up.

Invasive species are those that are not native to an area and cause ecological, economic, or social harm. Not all non-native species are invasive. For example, Black-eyed Susan (Rudbeckia hirta), Queen Anne’s Lace (Daucus carota), and Wild Chicory (Cichorium intybus) are all non-native, but I’d argue they do no real damage on PEI. Others - including Garlic Mustard – cause serious problems. 

Photo 2: Garlic Mustard is a bienniel, and flowers in its second year. The leaves of second-year plants are triangular compared to the more rounded leaves of first year plants (see Photo 1).

Invasive species usually have traits that give them a leg up over the native competition.  Garlic Mustard germinates very early in spring, giving it a head start (Photo 1). By the time surrounding native plants appear, this invasive is already established and outcompeting them for light and moisture. It flowers in early June (Photo 2) and each plant produces thousands of seeds, allowing it to rapidly colonize an area. Garlic Mustard is allelopathic – its roots produce chemicals that supress the growth of surrounding plants – and it also interferes with the beneficial relationship between nearby trees and mycorrhizal fungi.  Finally, Garlic Mustard is shade tolerant and easily able to invade forests and riparian zones.

Garlic Mustard was brought to North America from Europe more than 150 years ago as an edible and medicinal plant. It’s a relatively new arrival to the Maritimes, appearing in New Brunswick and Nova Scotia before being found on PEI in 2004. Since its first discovery here, Garlic Mustard has been found at four additional sites, all in Queens County. The initial site is a popular tourist destination, and I suspect Garlic Mustard seeds hitch-hiked on a summer visitor and the plant spread from there.

While Garlic Mustard is not something you want to grow, there is no harm in eating it if you find it.  (But please first report the sighting to the PEI Invasive Species Council and check out their website for tips on how to eradicate this plant).  Unlike some invasive species, Garlic Mustard cannot grow a new plant from bits of the stem or leaf of an old one.  It can regrow from root fragments, so care is needed if you are digging it up. 

Photo 3: Garlic Mustard Pesto.

Garlic Mustard is well named, with leaves that taste like a combination of slightly bitter mustard greens and garlic. The stem is even more garlicy and unopened flower buds have a bit of a spicy kick. (Garlic Mustard is a biennial, and so stems and flowers only appear on second-year plants).  Leaves are nice added raw to sandwiches or salads, or can be blanched and eaten as a side dish if you find them too bitter. Young flowering shoots of second year plants can be added to stir fries or blanched and sautéed like broccoli rabe.  Leaves, shoots, and stems can all be used to make Garlic Mustard pesto (Photo 3, recipe here: https://www.pei-untamed.com/post/garlic-mutard-pesto). 

Garlic Mustard’s culinary uses do not outweigh the harm it causes as an invasive species, and we can’t eat our way out of this invasive problem.  Do not grow Garlic Mustard and do report any sites found.  But if you are going to help with eradication, you may as well take the opportunity to taste this part of PEI untamed.