You Bet Your Garden

Groundcover gone bad


Listen to the full show:

Mike McGrath shares his recommendations for getting rid of weeds, correcting herbicide damage, pruning your trees properly, using manure in your garden, growing tasty tomatoes and the best way to beat Bishop’s weed. Plus: Mike speaks with Dan Sullivan, a journalist for Mother Earth News, about how herbicides are creating toxic compost.


Questions of the Week:

About five or six years ago, we noticed some ground cover that was not there before. It turned out to be Bishop’s weed. We do not want Bishop’s weed in our garden. I’ve been trying to pull out as much of the root as possible, but this has gotten harder every year, and it’s already coming up all over—in between everything else, which makes it even harder to pull. It’s out of control, and we’re concerned that it will kill the plants we do want. Is there any easy-on-my back, non-chemical way to get rid of this weed that some people call ground cover?

— Abraham in Burtonsville, MD

I’ve been fighting the noxious plant known as Bishop’s Weed for many years. I’m convinced it came with some iris and daylilies from my grandmother’s garden; apparently it was once a popular bedding plant. It is just now emerging from the ground, and I’d really like to get a jump on it this spring. I have won small battles forking the ground and then sifting through the soil to get every piece of the white roots. My aunt, who also had this problem from the same source, swears she eradicated the pesky plant through diligent weeding— preventing the leaves from feeding the roots. I don’t want to use Roundup because the plant is intermingled with a particularly wonderful border of native shrubs. It has been least successful in the vegetable garden where I attribute the cyclical turning of soil to keeping it at bay.

— Jill in Unionville, PA

I have been battling Bishop’s Weed for several years and have had no success. In fact, it’s more widely spread than ever! I’ve put lots of it in my compost pile. Could the pulled-up roots still be viable after months in the pile? Have I contaminated the pile?

— Pat in Havertown, PA

Find out how to get rid of Bishop’s weed »


Highlights from show for May 4, 2013:

Tools for getting rid of weeds

Gary from West Chester, PA bought a flame weeder about a year ago and is starting to wonder if there’s another method to kill his dandelions with it that doesn’t leave his yard looking polka dotted! Mike humorously adds that flame weeders aren’t only extremely useful for weeding the land, but also to take out personal aggression. He says, “Wave the flame across the top of the plant until it begins to wilt, and that’s the sign that you have now burst the cells inside that plant. Even though it just looks a little withered, it won’t come back. And you don’t have to stand there, turn the flame up to full blast, and toast the sucker into charred oblivion — although you can if you want to. This is your life! This is your world!”

Dandelions are a biennial plant that are highly nutritious and even edible when they have only the flowering leaves and not yet have any developed buds. Another alternative to taking care of these weeds, for those who are not pyromaniacally inclined, would be a water weeder, which can be purchased from Lee Valley Tools. It is a tool which has a long spike that enters the ground and floods the weed roots with water to even pop some of them out of the ground. They are then ideal for using in compost as they are highly nutionitious and beneficial for plants. So when it comes to those who see flame weeding as the only option, “The bottom line is, no, you don’t have to toast the plant, although if that’s your idea of a good time, you go for it,” Mike says.

  • Mike McGrath with a flame weeder

    Mike McGrath with a flame weeder


“… and you don’t have to stand there, turn the flame up to full blast, and toast the sucker into charred oblivion — although you can if you want to. This is your life! This is your world!”

Mike McGrath


How to properly prune your trees

Katie from Oklahoma City can’t bear the sight of the poor work some people did with cutting trees in her neighborhood. Apparently, some vans with no names on it have showed up in her neighborhood and been cutting down some of the tree branches, but leaving nubs and stumps on the branches instead of cutting off the entire branch. Mike commiserated, explaining: “It has no basis in horticultural sciences and it creates really ugly looking trees. Unfortunately I’ve noticed a great drop in technique and ability in people trimming trees. I see these random half branch cuts more often than not. If a branch is dead, damaged, or diseased, it should come off as soon as that is noticed, but you don’t cut it off at the elbow, you take it off a the shoulder.” In other words, the shoulder is where the branch meets the tree vertically and leaves a circular collar on the tree. It should be pruned in such a way that the collar remains uncut.

  • RELATED:

    A professional arborist explains proper pruning

According to Mike, when a butcher job such as the one Katie mentions is done, the tree will never look right again. “I think a lot of people, when they hire someone, assume that the person knows what they’re doing. But I have an entire email file of great regrets that people went out shopping during the tree trimming or the grass laying or the shrub installing process and came back to a horror show.”

Once it’s hot or the fall season, no pruning should be done. Only in mid winter or in the spring should this be taken on, so lucky for the trees in Katie’s neighborhood, there is still time to right the wrong and prune the rest of the branches correctly.


Special guest: Dan Sullivan on persistent herbicides in compost

Dan Sullivan, an adjunct instructor who developed the Masters in Sustainable Food Systems program at Green Mountain College, talks with Mike about his new article, “Killer Compost Update: Herbicide Damage Still a Major Problem” in Mother Earth News magazine. According to Dan, dangerous amounts of herbicides are making their way into finished municipal composts, which many gardeners turn to for their seasonal supply of compost. However, people are becoming increasingly wary of using such resources for fear of the contaminants that may be inside them. These chemicals also maintain their plant killing properties at extremely low levels.

“We’re talking about parts per billion. What’s really frustrating … is that the EPA has no real protocols for testing for these damaging herbicides at levels that are low enough to still damage plants,” Dan says. Most of the time these herbicides come from grass clippings that were sprayed with harmful chemicals or hormone plant growth regulators. Imprelis, for example, contains a chemical that is known to even kill full grown trees within a several mile radius of where it was applied.

Even though those administering these chemicals are required to have a professional applicators liscence, homeowners are oftentimes not told that they must not compost their grass clippings, but to leave them on the soil. Mike adds, “I don’t advocate the composting of grass clippings for other reasons. Grass clippings are the perfect food for a lawn. You’re crazy not to leave them on your lawn. When you recycle your clippings into your lawn you provide a third to a half of all the fod that your lawn needs for a given year!”

The problem, Dan says, is that the Environmental Protection Agency (EPA) does not currently regulate these contaminants becuase of the great expense of technology-such as spectrometers, for example- that could measure such minute amounts of ingredients in the compost. He does suggest a way that gardeners can conduct a bioassay to test their compost themselves in order to feel more safe in using it in teir gardens. Peas are one of the most sensitive plants to the types of herbicides most commonly found in these municipal composts, so Dan recommends that gardeners plant peas in the compost and also in a control of normal soil and watch if within about 10 days the peas start to sprout with the characteristic leaf curl of herbicide damage.

“People need to talk to the EPA because this has been going on for as long as I’ve been covering sustainable agriculture, which has been about thirteen years. It has been an ongoing problem.”

Dan Sullivan

  • The Chittenden Solid Waste District, the trash and recycling authority for Chittenden County in Vermont, has a speedy response to the presence of herbicides in their municipal compost pile.

How to use manure in a garden

Anita from Concord, California belongs to a community garden where several gardeners get fresh horse manure and spread it on their gardens before tilling it in. The gardeners do not compost the manure but spread it on their gardens raw. Concerned about potential antibiotic runoff in her garden from the horses, she consults Mike for his advice.

“Different barnyard manures were an integral part of organic gardening and farming, but now horses are probably the cleanest animals in this equation. You may have read that there’s been a tendency to feed chickens relatively enormous amounts of arsenic because believe it or not it makes the shells thicken on the eggs and they ship better,” he says. Similarly, cattle and dairy cows have large amounts of growth hormones and antibiotics in their systems.

Horse manure is mainly composed of nitrogen which is ideal for growing large plants, but not plants with plenty of fruit on them. But when it’s all said and done, “They shouldn’t be using raw manure, and they certainly shouldn’t be tilling it into the soil,” Mike says.


How to correct herbicide damage

Lois Anne from Lake Martin, Alabama is concerned about the health of her acuba. It will randomly lose its leaves, and the leaves that return are thin and discolored in places. Mike offered his assessment and solution: “What you describe sounds like classic herbicide damage … When you’ve got herbicide damage like that, what I want you to do is flush the soil at the base of the plant. And you know what, actually? Get out there with a hose and rinse the plant down, just spray it down every couple of mornings through the spring, really saturate the ground, and then give it a nice mulch of compost, and it should recover if no one goes spraying anymore.”


Growing the best-tasting tomatoes

Charlie lives outside of Quakertown, Pennsylvania, and he’s struggling to grow tomatoes that taste as good as the crop he grew when living along the coastal plains of South Carolina. Mike laments that Pennsylvania soil can be a challenge and suggests Charlie try growing in a raised bed. As far as getting the best tasting harvests, Mike has some suggestions: “Flavor is largely variety-driven, Charles. You have to grow the right kind of tomato to get that old-time flavor … I would urge you to try Rutgers; it’s one of the tomatoes that’s said to have that old-time Jersey flavor. The best-tasting tomatoes are the big heirloom varieties: Brandywine, Mortgage Lifter, Black Krim, Georgia Streak. They have a lot of leaf cover, and note that those leaves should not be removed as long as they’re a good color, because the really complex flavors need a lot of leaves to funnel all the nutrients to the developing tomatoes.”

Mike goes on to recommend supplements that will improve Charlie’s tomato flavor: “This year I want you to either go buy a natural plant food that says it has added calcium for tomatoes, or in every planting hole crushed dried eggshells or calcium-carbonate pills. You know those osteoporosis pills they sell in all the stores? … Get a big bottle of calcium-carbonate pills and bust up a dozen for each hole and put that in the planting hole. That’ll get rid of rot and improve the flavor of your tomatoes.”

“Flavor is largely variety-driven, Charles. You have to grow the right kind of tomato to get that old-time flavor.”

Mike McGrath

Slideshow below: Heirloom Tomato Varieties

— This week’s post was written by Jolie Higazi, You Bet Your Garden Intern




  • John Bond

    I have about 3 big bags of bat dirt from cleaning out a loft in a barn is it good to use in garden

    • Sarah Kaizar

      Hi John — Mike McGrath reviewed your question and advises: “I hope you wore a respirator; that S*** is extremely dangerous to inhale! Too rich to use directly, but you can mix it with lots of shredded leaves in a compost pile and then use the resulting compost. But be careful–don’t inhale any (more) of the dust!”

  • Carolyn Peters-Eckel

    What is the best way to have daffodil bulbs be nourshed for the next spring? Some people fold the over and they die down quicker but does this diminish the flowers the next year?
    Thanks

    • Sarah Kaizar

      Hi Carolyn — I shared your question with Mike McGrath, and he suggests you peruse the spring bulb Q&A in his A-Z Garden Answers. If you are still having trouble, please feel free to check in with us again. Thanks for listening!

  • Staci Groland

    My home is at the base of a sloping street. All of the runoff from my neighbors on this street (about 8 houses) comes through my yard. While I do not use any pesticides, I have no control over what my neighbors choose to put on their lawns/gardens. I am concerned about what pesticides could be seeping into my vegetable gardens. Is there anything I can do (aside from above the ground garden beds) to prevent exposure to the pesticides my neighbors use?

    • Admin

      Staci – Mike thinks you should contact your municipality. He believes that these kinds of drainage problems should be corrected. Additionally, he says: “yes–grow in raised beds.
      & If the situation is really dire, build a berm or other water diversion…. ”

      Thanks for listening -

  • Randi Stouffer

    I just had a dead pine tree removed from my yard in northern Illinois. What perennials can I grow in the old pine’s space, which now gets full sun?

    • Sarah Kaizar

      Hi Randi — I passed your question onto Mike McGrath, and he says “everything depends on whether the stump was pulled or not…” Did you have the stump completely removed?



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