Origin: East Africa, Mediterranean, Europe
Improvement status: Wild
Seeds per packet: ~170
Germination tested 12/2022: 89%
Life cycle: Annual or Biennial
As a non-native garlic-flavored wild green, garlic pennycress compares very favorably to the more common garlic-mustard (Alliaria petiolata), another garlic-flavored non-native green. Both are Eurasian natives that have become widely established in North America, but garlic-mustard has a much wider distribution, is found in a more diverse range habitats, has wide leaves that shade out other species, and its long growth cycle means keeps it shading out competitors all year. This species, however, avoids the "noxious weed" label because it is relatively unobtrusive on the landscape: it sprouts and grows very early in the season, before most other plants, and it is slender and rather spindly, so it doesn't disrupt the lifecycle of other plants by shading them out, perhaps besides other early-sprouting spring weeds (which in our area are also mostly non-natives, like foxtail millet and buttercup). In fact, we've begun assessing if it has a role to play as an early spring cover crop for agroecological farming applications, helping intentionally planted crops get established while preventing other weeds from taking over. Because its life cycle is usually complete by late spring, it doesn't continue taking nutrients from other crops and so could be a useful companion plant early in the season.
Garlic pennycress bears a close resemblance to the more well-known field pennycress (Thlaspi arvense), but it sets itself apart with a strong garlic flavor. Until very recently, it was considered to be in the same genus, with the name Thlaspi alliaceum, but taxonomists recently assigned it its own genus. It's often called "roadside pennycress", because that's where it's most frequently encountered. It thrives on any disturbed ground, usually in the presence of other non-native species.
First found in the US in Pennsylvania in 1947, it can now be found across the eastern US, at least from Louisiana to Massachusetts. These seeds come from volunteer plants at the EFN flagship farm in Elmer, New Jersey. It is one of our first flowers in the spring, and their nectar and pollen are very much appreciated by our honeybees and other early emerging insects. The unopened flower spikes can be harvested as a tasty garlic-flavored green for eating raw or cooking. We expect it'll prove great for sprouts too. And, if it's anything like its cousin the field pennycress, the seed oil may also have myriad uses (Thlaspi arvense seed oil is high in erucic acid, which makes it bad for human consumption, but great for jet fuel!).
GROWING TIPS: Sow in late summer, fall, winter, or very early spring. Will self sow readily once established. In New Jersey it grows as a biennial, sprouting and blooming in late winter.