Invasive of the Week: Dame’s rocket, Hesperis matronalis
Editor’s note: Like many organizations, our staff are doing work outside of normal job tasks–literally. When non-horticulture staff began work to help maintain our outdoor spaces, field services manager Jeff Plakke reminded us to pitch, rather than compost dame’s rocket after weeding. Read on for how Emily Lilla describes the difference between this fragrant, beguiling plant and a better native option.
Back by popular demand! Dame’s rocket, Hesperis matronalis, is a beautifully deceiving invasive plant that looks like our native woodland phlox but definitely isn’t. Brought over from Europe in the 1600s as an ornamental, dame’s rocket is a 2 to 4 foot tall, very hardy plant that thrives in gardens, roadsides, and disturbed areas. The flowers range from white to purple in color blooming in late May through the end of June. The flowers look similar to phlox, Phlox paniculata (non native) and Phlox divaricata (great native alternative for gardens), except dame’s rocket’s flowers have 4 petals while phlox has 5 petals. Dame’s rocket is considered invasive due to its ability to spread easily (even when confined to a garden) and tends to out-compete beneficial native plants that are critical resources for bees, butterflies, birds, and other wildlife.
Dame’s rocket can be removed by pulling out the plant (be sure to remove the taproot). It is best to place in a plastic bag and dispose of in the trash. It should not be composted due to its resilience: underdeveloped seeds of dame’s rocket can still sprout just like its relative, garlic mustard. Dame’s rocket belongs to the mustard family and is related to arugula.