fighting weeds: mugwort and prunella
IF I PRACTICED CHINESE MEDICINE, I’d be all set with enough mugwort (Artemisia vulgaris) and self-heal (Prunella vulgaris) to stock an herbal pharmacy. Whatever their positive properties, though (and self-heal happens also to be native), I see these two ambitious perennials as weeds, and need to tackle them.
My first step with any weed—meaning: wrong plant, wrong place—is to I.D. it, as I have said before, and try to understand its life cycle, so I have a shot at approaching it in the most effective way, and at the right time of year. (More on how to do that, and a link to weed I.D. tools, is at the bottom of the page.) Since both of these grow from rhizomes, I know I have my work cut out—and probably won’t do better than reducing them, with complete elimination unlikely.
THE NURSERY INDUSTRY agrees with me on this one: bad news. In the Eastern U.S. and Canada, it’s a major issue, because mugwort’s energetic rhizomes can quickly overtake places where regular cultivation isn’t called for, such as a row of trees or perennials in the field, and the plant can reach 4 to 6 feet tall each season, swamping the desired crop.
Easy to confuse when it first emerges with chrysanthemum, with other Artemisia, and even maybe with ragweed, Ambrosia artemisifolia, one way to tell you’ve got mugwort is its leaves, which are bright green on top, but silvery on their undersides. There’s another foliar clue, which is that the lower ones (just above) are less finely cut than the ones at the top of the plant (as in all the other photos). Again, whether top or bottom leaves, they’ll be green on the upper surface and silver underneath.
Despite its use in moxibustion (when an acupuncturist applies heat from the burning leaves to a point on the body), in Ayurvedic medicine, and even (sparingly) to flavor food in parts of Europe and Asia (and in the past to flavor beer), I’d like mine gone. It has insinuated itself in a big island of perennial ornamental grasses (above), where I cannot easily cultivate repeatedly to try to break up the rhizomes and expose them to the surface, where they’d hopefully dry out. I’m left to pull and dig rhizomes after a good soaking rain or watering, to try to at least set it back.
THIS LITTLE MINT RELATIVE, an enthusiastic type, loves the rougher areas of turfgrass here, and especially shaded, moist ones. When exposed to regular mowing, it adapts to stay just low enough to escape much damage from the blades, staying quite compact, so mowing isn’t a tactic for fighting it.
I could make a lot of tea from my bountiful supply, and self-heal has been used through the ages as a remedy for immune and skin issues, hypertension and more. And at least it’s green, and low–and bees and butterflies love its little purple flowers, which develop in early summer, though of course that means late-summer seeds, and more Prunella. It’s technically a native plant throughout the U.S., so no surprise I suppose that it’s popular with the insects.
I have plenty to make loads of insects happy, but in a few very prominent spots I’m planning on a little Prunella reduction campaign mid-August into mid-September, timed to coincide with the best window for lawn re-seeding here, when I will hoe some of the biggest patches out and sow turfgrasses and clover. Thankfully, self-heal’s roots are not as formidable as mugwort’s.
I KNOW, you’re probably thinking: Doesn’t she have anything to do with herself but figure out the names of her weeds? (That’s clearweed, or Pilea pumila, above, and Galinsoga ciliata, below.) There I go again, but it really does help. The links below the photo might help, too.
- How to ID your weeds—links to online guides
- A 101 approach to weed control
- Smothering weeds with cardboard and newspaper
- Piling on the mulch for weed suppression and control
- Clearweed, or Pilea pumila
- Hedge bindweed and spotted spurge
- Garlic mustard, Alliaria petiolata
- Galinsoga and Commelina
- A weed I accidentally planted, Houttuynia or chameleon plant
- All my weed stories
- An interview with the author of the field guide “Weeds of North America,” on weed ID