Dame's Rocket AKA Hesperis matronalis

The more I add entries to this blog, the more I realize I may not be the right person to be writing it!  I'm afraid I have a fondness for a several of these plants presently considered invasive.  I'll explain.  We've owned several period homes over the years, and when we moved to each one, I searched each property for any remnants of garden plants that may have been planted and survived over the centuries.  For years I have been poring through antique garden catalogs from the 19th century, as well as any gardening books, both old and new, that referred to plants grown in past centuries for both their ornamental appeal as well as their food value. I still remember sitting in front of a fire one winter about twenty-five years ago perusing a seed catalogue from a Union, Connecticut company called Select Seeds.  It was a modern-day catalogue that offered a variety of seeds for antique ornamental plants.  Next to each antique plant represented, there was a little blurb about the plant's history.  Because of its fragrance, abundant showy flowers in shades of lavender to white, and its early history of arrival on our shores, Dame's rocket is one of the seed packets I selected.  Truthfully, I'm surprised the plant was not already growing on that 18th century property as the plant was imported by Europeans arriving on our soil way back in the 17th century.  It has naturalized on my present property.  I did not plant it here.  It is a possibility that it has been growing here since our present house was built in the last quarter of the 1700's.

Hesperis matronalis is a plant with about a million different common names, Dame's Rocket is the one most commonly used in the U.S.  It is a biannual plant said to be native to southern Europe with a range from Spain to Turkey.  It is now naturalized through much of Europe, the US and Canada.  The word Dame's was likely taken from Damascus, a Syrian city near Turkey, and rocket from the French word roquette a referral to the plant being in the cabbage or Brassicaceae family. The Hesperis portion of the Latin name is a reference to the plant's fragrance which becomes stronger in the evening. Hespera is the Greek word for evening.  Dame's rocket is in the mustard family, another cruciferous vegetable like broccoli.  Many parts of Hesperis matronalis are considered edible. Here is a link to a site called Forager Chef should that aspect of this plant be of interest to you https://foragerchef.com/dames-rocket-hesperis-matronalis/ 

This plant has had ample time in its over three hundred years presence on our shores to escape gardens and disrupt native plant growth.  It has naturalized in many areas.  It is a biannual meaning the first year it grows as a rosette of foliage.  It is early to emerge and the reddish color of its foliage upon emergence provides the plant with protection from the cold.  In its second year of growth the plant produces flowers and seeds.  Its growth very early in the season allows it to crowd out native species.  As with garlic mustard, it is a highly prolific seeder.  A single plant is capable of producing 20,000 seeds!  In Connecticut this plant is considered invasive, and it has been banned.  It is presently not legal to sell or to transport this plant.  It is considered invasive in other states as well.  The seeds for Dame's rocket may well be contained in some wildflower seed mixes, so take care not to inadvertently introduce this plant to your landscape in that manner.

The plant is easy to spot in the months of May and June when it is in bloom.  Be careful not to confuse it with native phlox which it resembles.  By observing the details, it is easy to distinguish them from each other. Dame's rocket has four flower petals versus phlox which has five petals.  When observing the foliage on dame's rocket, you will notice the lance shaped leaves grow in alternating fashion along the stem versus phlox which leaves grow in opposition or directly across from one another along the stem. Another non-native plant it resembles is Lunaria annua which is commonly called honesty, silver dollar, or money plant.  Lunaria annua has heart shaped leaved versus the lanceolate formed ones found on dame's rocket.   Lunaria annua also has those silvery round flat seed pods sometimes used in flower arrangements.  It too is a plant in the mustard family.  Lunaria annua is not considered invasive in Connecticut.

HOW TO REMOVE

Hesperis matronalis is easy to pull out by the root especially after a good soaking rain.  It is best to bag the pulled plants in a large heavy duty trash bag and bring the bagged plants to the landfill where they will be burned.  Do not compost them as they will grow in your compost pile and spread from there.  A follow-up pulling will likely be necessary the next several years, but over time the plant will disappear from your landscape.  This same method of removal works for garlic mustard. 

Should you choose to use an herbicide, it would be best to use a selective herbicide that will not harm grasses.  Apply it later in the fall months.  A late in the season application will help prevent the spraying of desirable native plants most of which die back before dame's rocket.