The Other Invasive Mustard—Dame’s Rocket

Hesperis along tracks

In the world of mustards, garlic reigns supreme. Culinary tastes aside, Alliaria petiolata (Garlic Mustard) is perhaps the most notorious invasive plant in the mustard family. It’s proclivity for infiltrating and colonizing natural areas justifies it’s top billing. Regrettably, there’s another invasive mustard that deserves to be on your radar—Hesperis matronalis (Dame’s Rocket).

Frankly, Dame’s Rocket has a lot going for it—it’s attractive, fragrant, adapts to a range of growing conditions and self-seeds easily. It’s redeeming qualities have made it a popular component of “prairie in a can” wildflower mixes. Unfortunately, once planted this Eurasian native easily escapes cultivation and has the potential to be every bit as horrible as it’s relative, Garlic Mustard.

Identification

Like Garlic Mustard, Dame’s Rocket is a biennial, meaning it completes it’s lifecycle in two years. It forms a basal rosette in it’s first year and then, in it’s second year, sends up a 2-3’ flower stalk. The leaves are an elongated heart shape and serrated. Flowers range from white to pink to purple and closely resemble native Phlox. However, Phlox has five flower petals while Dame’s Rocket, like all mustards, has only four. In Northwest Indiana, Dame’s Rocket generally blooms in early to mid-May.

Plox-Dame's Rocket

Native Phlox (left) has five petals whereas Dame’s Rocket (right) has four.

Eradication

First and foremost, don’t plant wildflower mixes that contain Dame’s Rocket. If plants are present on your property, pull them in early spring when the soil is moist—taking care to disturb the soil as little as possible. Like Garlic Mustard, Dame’s Rocket should not be composted or placed in kraft yard waste bags. Deposit pulled plants in heavy-duty plastic lawn bags and dispose of them with your regular household trash.

Glyphosate or Triclopyr can be used on large infestations. Apply to foliage in early spring or late fall when native vegetation is dormant.

Landscape Alternatives

May is a great time of year for flowering natives and it’s easy to find quality additions to your mid-Spring landscape. For dry woodlands or dune slopes, typical of the Black Oak Savanna found throughout much of Duneland, wildflowers include Viola pedata var. lineariloba (Bird’s Foot Violet); Phlox bifida (Cleft Phlox); Aquilegia canadensis (Wild Columbine); Lithospermum croceum (Hairy puccoon); and of course, Lupinus perennis occidentalis (Wild Lupine).

Geranium maculatum

Geranium maculatum (Wild Geranium) is a great alternative to Dame’s Rocket and will thrive in mesic woodlands.

For those with a bit more shade and moisture, try Geranium maculatum (Wild Geranium); Sanguinaria canadensis (Bloodroot); Trillium recurvatum (Red Trillium); Uvularia grandiflora (Bellwort ); or Mertensia virginica (Virginia Bluebells). Polygontum sp. (Solomon’s Seal) and Smilacina sp. (False Solomon’s Seal) are showy options as well and are found growing throughout Dune Acres.

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