weeds to target late summer and fall

"How to Eradicate Invasive Plants" by Teri Dunn ChaceAN ENCORE VISIT to my public-radio show and podcast by Teri Dunn Chace, author of “How to Eradicate Invasive Plants,” happened just in the nick, I do believe. Late summer and fall turn out to be the best time for getting the upper hand over a wide range of common weeds, including Japanese knotweed, ragweed, Ailanthus, bindweed, curly dock and more, so I was relieved to have Teri join me again to chart a focused course of action. Get her tips, enter to win her book—and just listen in as we gripe about weeds, and grapple with them together.

No matter what weed you are facing, if it’s flowering or setting seed now, be sure to behead it: mow it down, harvest the blooms for bouquets, or otherwise prevent a successful sexual reproduction cycle.

prefer the podcast?

TERI DUNN CHACE, author of “How to Eradicate Invasive Plants,” was the guest on the latest edition of my weekly public-radio show and podcast. Listen anywhere, anytime: Locally, in my Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) region, “A Way to Garden” airs on Robin Hood Radio’s three stations on Monday at 8:30 AM Eastern, with a rerun at 8:30 Saturdays. It is available free on iTunes, the Stitcher app, or streaming from RobinHoodRadio.com or via its RSS feed. The August 19, 2013 show can be streamed here now. Robin Hood is the smallest NPR station in the nation; our garden show marked the start of its fourth year in March, and is syndicated via PRX.

teri dunn chace’s basic weed strategy

FIRST A FAST REVIEW of Teri’s basic strategic weed-fighting plan, since simply pinpointing specific things this time of year isn’t the whole story.  Her plan, she admits: mostly practical and straight-forward.

“Although it’s common sense, it’s things we sometimes don’t do,” says Teri, “but if we did it would make a big difference.” Don’t let things get to where you want to turn to the store to buy some chemical to erase your weed woes. Follow her strategic plan instead:

  • Knowledge is power: ID your weeds (otherwise how do you know what it will take to defeat them?).
  • Intervene early (too late for that now, but really: this is the key of all keys with weeds).
  • Good timing is key: Each plant has a life cycle, a biology, and knowing what its cycle is can help you figure out when to best expend your efforts against it. (This is where ID’ing it first comes in, particularly.)
  • Assess the situation. How bad is the problem, and how many different problems are you facing? Which then dovetails to…
  • Concentrate your efforts. Start with the worst infestations, and worst outward from those for the greatest benefit.
  • And then this: Persist. One pass once a season won’t do it.  Be realistic, and relentless.
  • Chemicals are, if anything, a last resort (and I don’t use them at all). Teri’s weed-removal regimen is an example of that “first, do no harm” code of ethics; too-aggressive warfare can kill more than a single weed. Don’t use an herbicide unless all else fails, and if you do, use the correct one at the correct time applied in the correct manner (which often is not spraying all over everything wildly, but rather a pinpointed approach).

weeds to target now (a partial list)

Ragweed: Ragweed, or Ambrosia artemisiifolia (not goldenrod, or Solidago, whose pollen is too heavy to blow around and into your nostrils) is the major culprit in fall allergy season. “You really want to catch ragweed right now,” Teri says of the plant, whose copious seeds live decades in the soil. Ragweed is wind pollinated, producing inconspicuous seed after wands of greenish small flowers ripen. The seeds can last for years in the soil, and beyond that: the plant’s allelopathic, creating inhospitable conditions for neighboring plants by exuding chemicals. Mow down or behead ragweed before seed is set. (Images to ID it from seedling through maturity are here.)

Purple loosestrife: A damaging weed, especially in moist areas, that uses more than one method to reproduce, including sowing itself around after flowering. At least cut off the flowers of this one (Teri likes them in bouquets). Mowing and burning are other tactics for limiting its growth, but digging out other than small infestations is impractical because of the dense stands that Lythrum salicaria forms.

Hedge bindweed flower, brachtBindweeds are setting seeds around now from their morning glory-like flowers. I have the larger hedge bindweed (Calystegia sepium), above; the smaller-flowered and -leaved wild morning glory (Convolvulus arvensis) is even more common in many gardens. The latter may also be allelopathic, releasing chemicals that deter other plants from thriving nearby.  Both reproduce from seed and from roots and root fragments (meaning if you dig unsuccessfully and leave bits, oops!).

If the vines are currently engulfing desired plants and you can’t pull them off without doing damage,  Teri says, “trace the plants back to its roots, if you can, and dislodge the roots and just leave the rest all there. After a week or two, the rest should brown off.”

Can’t get to the roots right now to complete the eradication? At least pinch or pull off the flowers of either species (to prevent self-sowing) and/or as many of its leaves if you can (to further weaken the invader). When you can get into the area, work to dig out the strong roots or rhizomes.

Curly dock, Rumex crispusCurly dock: Rumex crispus or curly dock (above) is another wind-pollinated weed, meaning it’s tossed about your garden by the breeze.  Besides its prodigious seed production, curly dock has an impressive taproot, making it very hard to get up and out completely, but use a garden fork (easier after a rainstorm or a soaking with the hose) to try. “The minute you see dock bloom, chop off the flowers,” says Teri about the tiny reddish-green blooms. Are you surprised to hear that this one’s in the same family as Japanese knotweed, the Polygonaceae?

Japanese knotweed: This widespread invasive spreads by seed (dispersed by wind, animals, or brought in on contaminated fill) as well as by rhizomes that bamboo’s, and though its common name is Japanese bamboo it is not a bamboo relative.

Dig up rhizomes when practical (not always practical, as they can reach massive proportion), or at least cut back topgrowth repeatedly, especially in late summer and fall, to weaken the root system.

“Then smother the area with thick mulch and/or a tarp and leave it in place for at least a year, perhaps longer.”

Important: If herbicide is used, late summer or fall’s the time, not spring, for it to be effective. Apply it on chopped-back plants, not giant stands. The only good part of this story: An extract of the roots is used in a treatment for Lyme disease.

Ailanthus altissima: The so-called tree-of-heaven is no heavenly creature, and with ongoing invasions in mind it’s going to seed about now.  Also in its territory-grabbing arsenal: it’s allelopathic, emitting chemicals that keep away other plants. Chopping it back doesn’t work; the roots resprout. Either get them all, or if the tree is already of decent size, some gardeners cut it down and paint glyphosate on the cut stump in summer or early fall. This is one where Teri’s advice “start early” (as in pulling or hoeing right when the many seedlings emerge) is the best path of all

how to win the weed book

I’VE BOUGHT TWO MORE COPIES of “How to Eradicate Invasive Plants” by Teri Dunn Chace to share with you. All you have to do to enter to win is let us know the answer to the question (share yours in comment box below):

What weeds are you going to tackle this late summer-into-fall?

Besides my hedge bindweed, I’m maniacal at the moment about Asian bittersweet; ground ivy (Glechoma hederacea) and the young plants of garlic mustard (Alliaria petiolata), all of which I want to dig so they don’t mature next season. Wish me luck (and same to you!).

Have no answer, or feeling shy? Just say, “Count me in,” and I will.

(Disclosure: Purchases from Amazon affiliate links yield a small commission that I use to purchase more giveaway books.)

Two winners will be chosen at random after entries close at midnight on Monday, August 26.

August 19, 2013


  1. Charles Klaer says

    At 69 while I still have the energy, my goal is to eradicate buck thorn from 20 acres, then to similarly take on honey suckle. I hope to have oaks take hold before the emerald ash borer devastates thousands of local ash.

  2. susan says

    Watch out for stilt grass. It is extremely invasive and is taking over everywhere in my area (NE Putnam). While it is one of those pretty weeds (looks like short Bamboo) it is taking over. It is an annual weed that spreads by seed.

  3. benjia morgenstern says

    Like Charles, I am also 69 with lots of will and waning strength but the gosh , darn dandelion weed in my grass and driveway drives me nuts. You can often find me with “fanny in the air” digging towards the center of the earth, to eradicate this tap root.
    I only have a 1/4 of an acre so hats off to Charles and his 20…

  4. Kimberly says

    Apparently, the same rings true with plants, as with castoff items…”One person’s trash is another person’s treasure”. I have read about so many people trying to eradicate honeysuckle and I’m trying to establish enough to cover a fence.
    I have wonderful childhood memories of its sweet scent, and of eating the “honey” out of the flowers. Well, I guess I understand that honeysuckle can “take over”, but not a worry of that here, so far.

  5. "wally" says

    Just got onto this great site, and have only viewed comments down to dandelions. I have dandelions and find them very beautiful! Why pay for flowers when nature provides them for free???, AND they are edible.

    You can’t eat grass OR make wine from it!

  6. janet c says

    I’m going to try to get rid of the thistle which seems to pop up everywhere. But the butterflies really like it.

  7. Mickie says

    I have successfully eradicated thistle and garlic mustard! This fall and spring I am going to work towards getting the ground ivy (Glechoma hederacea) at bay. My neighbor left a vegetable garden he could no longer attend exposed and the ivy has overcome that area and creeps constantly into mine.

    • says

      Hi, Mickie. The Glechoma is quite ambitious this year — I have dug up/pulled wheelbarrows full over and again. Ah, the garlic mustard…not sure I will ever get rid of it, but it is banished to some corners here and there.

  8. Madeleine Tierney says

    My front lawn is stilt grass and the back is ground ivy and violets. My strategy is to keep enlarging the planting areas!

  9. Kimball says

    I have an atrocious bindweed problem that I will be tackling in the next week or two. It has become very, very bad, and will be a long, laborious project over the next year or two to get it manageable.

  10. Lynn Dunning-Vaughn says

    Just this week on local NPR station, WAMC, retired NY State Pathologist, Ward Stone, said that Milkweed is the sole source of nutrition for Monarch butterflies. A woman called in to say that she propagates Milkweed in one section of her yard to attract Monarchs. Dr. Stone responded that many more of us should allow Milkweed to exist in order to increase the nationwide decline of the species. When is a weed not just a weed?

  11. says

    I’m still trying to do away with Creeping Charlie! He is aggressive and not easy to kill. I have to MAKE SURE to get all the roots! I’d love the book!

  12. Mary Kowalski says

    I am growing a lot of native species (weeds) such as Milkweed for the butterflies and intend to plant seeds again this fall once the pods ripen. Around our vacation home there are a number of what some would call weeds and what the butterflies and bees and I call nectar sources or host plants for the caterpillars.

    If you decide to buy the book, please consider a non-Amazon source. While I am a Prime member and love the convenience of shopping for items I can’t find easily in local stores, I am boycotting Amazon right now as are 900 authors who are in a power struggle with the giant retailer. There is a story in the NY Times today that explains the whole thing. I like Powells books on line and local stores if they still exist.

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