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fighting weeds: mugwort and prunella

mugwort and prunellaIF 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.

mugwort artemisia vulgarismugwort (artemisia vulgaris)

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.

lower leaves mugwortEasy 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.

mugwort in grassesDespite 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.

prunella vulgarisself-heal (prunella vulgaris)

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.

Clearweedm or Pilea pumilawhy i learn to i.d. my weeds

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.

Galinsoga ciliata, or Galinsoga quadriradiata, a weed

CategoriesFeatured weeds
  1. marcia says:

    I have a lot of the bad Celandine-creeping type buttercup. (maybe it is not a Celandine?) It has eaten a large portion or one lawn. And was tall and blosoming in one of the Pachysandra beds when, low and behold something ate all the leaves and yellow flowers and left the 10 inch stem sticking up totally naked. Any idea what did the job? I have little hope that it will deter it much from continuing to overtake the yard. I figure when it does we will have to move… thanks, mj

    1. Kathy says:

      Nobody has mentioned Microstegium vinimeum (Japanese stiltgrass) – I am plagued with it. An annual with zillions of seeds that remain viable for YEARS. We have been pulling it all out – in flower in August – or at least weed whipping off the loathsome flowers, but each summer it comes back with vigor. Aaaaaaaaargh! Any thoughts? And also wild strawberry in the lawn – I am not a big lawn fan, but I like a little grass with the weeds. have spent a fair amount of time hand-pulling, isolating with an edger, etc…. but it is winning. Without devoting my entire autumn to its removal – any time-saving (natch – non-chemical) thoughts?

      1. margaret says:

        It is a horrible thing, and many people (on other stories, not here) have talked about their issues with it. The National Parks Service Alien Plant Working Group has this to say. It’s an annual, so the key is to prevent it setting seed for next year’s infestation. The Nature Conservancy says to pull the plants from the ground before they flower in a small infestation, or for large areas, weed-whack (or mow on a VERY low setting) “the plants to the ground in September, shortly before it produces seed but too late for it to regrow before the first frost.” Repeat the following year — again with the goal to prevent flowering/setting seed.

  2. kathny says:

    I’ve been having terrible mugwort issues for the last couple of years. It has completely taken over a hill by my driveway, choked out everything that was planted there and nothing will eradicate it! I was going to till the hill and rake it out but I’m afraid of making the problem worse. I had the stiltgrass problem for a long time and thought I finally had it under control with constant vigilance but now I see it’s just moved to a different part of the garden and we have to start all over again. It just never ends, does it?

  3. Lorrie Lewis says:

    Box elder has invaded & taken possession of my ornamental grass garden and ground covers. Is there any solution short of digging everything up?? It’s terrible; thanks neighbor!

  4. Michelle says:

    I thought I had creeping Charlie, but maybe it is prunella (or a mix of both). I will have to go inspect that problem area in more detail. My other problem that started a few years ago is weed plantain, popping up in a spot where I seem to be forever digging them up. I’m going to take your advice and get to know my weeds a little better to see if I can make some headway.
    One weed I have kept at bay is garlic mustard. I had volunteered on some garlic mustard brigades at local parks and a friend’s property,so I can recognize that nuisance as the tiniest sprout. I haven’t been shy about educating my neighbors about it which has helped keep it away. Unfortunately I still see it around the neighborhood so it is a constant vigilance.

    1. tina says:

      You can eat healthy plantain leaves in your salad. Just tear them up and steam them.
      Garlic mustard leaves are very tasty, you can eat them raw or steamed. Spicy.

  5. Sandra R says:

    I blindly “hosted” mugwort, confusing it with chrysanthemum, for the first two years after we moved to a new house. As you can imagine, when a kind student of horticulture broke the news to me, I was behind the game big time. I have accepted that I will never be free of it here. Ironically, I also have it under decent control in my flower gardens. Mainly by pulling it hard in the spring (including the brittle white roots, so pulling and digging), when it is small. Also my husband will paint herbicide on the leaves or spray if not near other plants. When I read it is thought to be cancer preventative in the Asia, I thought I could probably provide enough for China in my yard!! Horrid plant.

  6. Charlie says:

    Not sure of the name but I found a new one in my garden that has long tentacles. When you pull it up there can be ‘arms’ in many directions in a red color. It comes up easy but I’m sure it will be everywhere soon! And I’m still serving little maple seedlings all over!

  7. Lauri says:

    This posting sent me to bookstores and libraries today to try to put a name to a weed that plagued me for 15 years in my Pittsburgh garden. (I have never seen it here in upstate New York, nor do I ever want to.) I believe I have identified it as groundsel (senecio vulgaris). It has a deep green basal foliage and sends up yellow flowers that turn to fluff and re-seed THROUGHOUT THE ENTIRE PERENNIAL GARDEN. They are secured by a taproot whose tip appears to go clear to China. Digging was ineffective. Isolated applications of Roundup would eliminate the plant I applied roundup to but before it was dead fifty more would appear in the garden. It was difficult to apply Roundup without affecting perennials because the foliage would invade every plant within its reach. It literally made me want to kiss any weed that pops out easily. Has anyone experienced this most heinous weed?

    1. margaret says:

      I haven’t had it here, Lauri, but I have read that because it generally manages to succeed by being a prodigious self-sower, smothering the areas with 3 inches of medium-coarse mulch (nothing too fine or too chunky, but medium texture) prevents the next generation from getting going. Also of course not letting it go to flower — so deadheading. Its seeds are not long-lived, maybe a year or two, so if it doesn’t flower for a year, you’ll start to get ahead of it, gradually having few to no new seedlings. I don’t know how many plants of it you are troubled by, of course…so this might be easier said than done!

  8. Cher says:

    What helps is knowing if it is a annual or perennial. An annual gets tugged out of the soil a perennial gets dug. And in the case of two different weeds I have round up. I am so allergic I bleed from my skin.

  9. Ellen Blackstone says:

    Finally a name for it: Prunella vulgaris. An *ambitious perennial*, indeed. Not bad looking when it first turns up. Fills up that little bare spot. Look, a lavender-like flower. …. …… OMG, get that horrible thing OUT of there! But I’ll taste it, next time I’m hacking away at it. Thanks, Margaret!

  10. jan M says:

    My FAVORITE resource for IDing weeds: “Pest Identification Guide for Weeds, Insects and Diseases of Woody Ornamentals” from the UMASS extension bookstore (~$18 + shipping direct from them).

    For weeds, it has 3 photos each of 135 different weeds – including growth habit, + 2 other significant features -seedling, flower, leaf, or seedpod, common name and botanical name. It’s my “Go To” book anytime I see something new in my lawn or garden. Websites are great, but theres nothing like having a book with you in the garden to compare your weed to the picture. It’s where I identified clearweed, mugwort, smartweed, spotted spurge, bittercress, among others.

    Weeds (135 ID’ed) are broken into Summer Annuals, Winter Annuals, Biennials, Perennials.
    Insects (67 IDs): defoliators, piercing/sucking, leaf miners, gall formers, scale insects, bark beetles, wood borers, root & shoot attackers, nuisance pests.
    Diseases (35 IDs): blights, cankers, galls, leaf spots, needle casts, phytoplasma, powdery mildews, root disease, rust diseases, vasular wilts.
    Abiotic factors – 8 – including winterkill, road salt damage, herbicide injury, marginal leaf scorch – things you may see and wonder what it is…

    “Good identification of your pest problem is the first, key step to successful management! This photo guide has over 80 pages of clear color photographs for the most frequently encountered weed, insect, disease and nonpathogenic disorders of ornamental trees and shrubs in the Northeast.”

  11. Anne says:

    My abandoned veggie garden was overgrown with mugwort, and a friend rototilled it last year. Much to my surprise, the mugwort was seriously set back. No maintenance last year, and no tilling this year, but the mugwort is still at a minimum. However, Houtuynia seemed to be spread all over from the tilling!!!

  12. Beverly, zone 6, eastern PA says:

    I am almost completely successful in eradicating my Mugwort, after dedicated pulling, many months in a row, each year for about 6 years. It was mixed in with perennial asters, daylilies, inside a blanket of Creeping Thyme and tangled at the base of Buddleias.

    The Prunella has shown up in small patches which I ripped out just because I had a bad feeling about the plant. Thanks for validating my hunch.

  13. lynne says:

    I’m a big fan of prunella as ground cover and as green mulch. It stays green (better than grass), is beautiful in large swaths, and can fill in quickly. Mugwort and sheep sorrel are the banes of my existence!

  14. Beth Urie says:

    Two weeds I learned from you: commelina and galinsoga … I sing these beautiful words as I pull :) Thank you.

  15. Brad May says:

    self-heal – a native that i can use as a medicinal tea
    (so much so, its name is self-heal)
    that attracts and feeds native insects.
    The plant has a long history of medicinal use,
    used for treating liver complaints, acting as a stimulant in the liver and gall bladder. Selfheal shows antiviral properties, and in China it is used as an anti-cancer drug. / 20%, Protein
    wont get over a foot tall
    and looks MUCH better than grass…

    why would i want to get rid of it ?

    1. margaret says:

      Sometimes even the beneficial plants end up in places you might not want them — that’s all. I have boatloads of Prunella here, and the beneficial insects love it at flowering time, but in a few very prominent spots in the lawn, by the front path and other key areas, I try to encourage the grass instead just for aesthetics. Not eradicating it by any means, promise. : )

      1. MB Whitcomb says:

        Good answer Margaret, and I would add, that if you have valuable land in its fairly pristine state, it will not be for long. I am very suspicious of all of the Prunella being native…I look at how organisms are using plants as a clue to how “native” they are. Nine times out of ten, if there are no folivores eating the plant it is out of place. I am not a taxonomist, so can only wonder…need to go get a PhD:P

        But on prunella, take a fairly dry day (so the plants are not brittle from water), and a rake…rake from outside the patch inward, and you will find a lot of the “arms” of the plant are then much easier to dig up. A strong hand hoe with a sharp tip works well to bring up the roots (I get mine from AM Leonard for about 15.00, has a red handle, EXCELLENT tool). I find two days after a good rain is optimal, as the soil is not concrete, nor to soggy.

        I have fibromyalgia, so if I don’t figure out the least “body-intensive” way to do things I would have to give it up…and I have 12 gardens under my care at the moment;)

  16. Emily chiu says:

    What about lady’s thumb? How bad are these? I once thought they were a nice filler for bald patches but am I going to regret it?! I’m in zone 7 in New York City

    1. margaret says:

      Hard to be sure from a common name but it’s probably another alien weed (from Asia, I believe), a Persicaria that I call smartweed (more about it here). It’s related to buckwheat. I remove it because it just reproduces too enthusiastically. There are native species of Persicaria as well, but I don’t seem to have them here, just one of the aliens.

  17. Laura says:

    I attack mugwort in the early spring when the ground is bare, since it pops up before most other plants in my perennial garden. Pulling it out is easier when the ground is moist. It will be taller than many of the flowering plants I want to enjoy later in the season. When I spot it later but can’t get to it, I use a telescoping lopper to reach in and cut it back. It’s all over my rural neighborhood, so I know this will be an ongoing problem, but there does seem to be less in my perennial beds.

  18. Ellen Blackstone says:

    Prunella …. mint…. I should have known! But you know, it’s pretty — for a little while. And then, when it dies back, it leaves a big, brown, messy dry spot. It does pull up easily, though. Thanks for all the info, Margaret!

  19. Rose says:

    My prunella doens’t look anything like yours and is not a problem. It’s more a problem keeping other things from overrunning the prunella.
    Mugwort however, is a big problem! We found that the more you pull it out or try to dig it up, the more you get. Every little piece of broken root grows again. Only systemic herbicide will kill all those roots, and it takes a few applications until you get all the recurring plants from the all those broken roots you left in the soil in earlier attempts to get it out.

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