That weed that’s spreading all over might be Japanese knotweed!


Mike McGrath offers suggestions for protecting your saplings, the best recipe for compost, combatting weeds organically, how to build raised bed gardens, guarding against rabbits and how to get rid of Japanese knotweed. Plus: Mike speaks with Chelsey Fields, vegetable product manager for The Cook’s Garden, about special gourmet herbs cultivated on a mountaintop.

Questions of the Week:

I’ve got a quarter acre of Japanese knotweed. Is there any good use for the ten foot tall stalks besides making tomato trellises? Digging it up by the roots is good exercise, but I fear I’ll never get anything else done, as they just keep popping up. How do I assure total elimination?

— Kaki in Tunkhannock, PA

I have a bad case of Japanese knotweed. Any suggestions on eradication other than explosives?

— Scott in Stafford, VA

We have Japanese Knotweed taking over the stream banks that run through our property. It seems to like wet areas. It has been suggested to cut the stalks and paint the cut ends with Round-Up, which I really don’t want to do. Can you suggest another solution? This weed is tough and just keeps coming back year after year.

— Keith in Bryn Mawr, PA

Learn how to get rid of Japanese knotweed »

Slideshow below: What does Japanese knotweed look like?

Highlights from show for June 8, 2013:

Protecting saplings from the heat and nibbling critters

John from central Louisiana wants to plant a three-acre plot with Loblolly Pines, which are native to the area. Trouble is, Louisiana summers are so hot that they burn up the Bermuda grass currently on his plot, which John never even mows. Summers that can do that, says Mike, are “almost like the punch line to a bad joke.” Rabbits and deer also threaten to eat up the little seedlings before they even get started.

Mike advises to plant the young trees in the fall, about September 1, for the best chance of survival. He also suggests planting 2-3 feet saplings rather than younger 8-12 inch seedlings, if the larger plants can be found. If only smaller seedlings are available, Mike says to pot them. The young trees should be protected with cages made of chicken wire or animal fencing until they are about four years old; sapling “delicacies” are too tempting to be left defenseless amongst grazing critters. Because Loblolly Pines eventually grow very tall, planting saplings at least 20 feet apart is also essential.

“Atomic” compost / Compost gold

Matt from Adamstown, Pennsylvania has had limited results with composting in the past, but he now has access to a trove of rich ingredients: 20 gallons of coffee grounds every month in addition to unlimited spent barley and some straw chicken bedding. What can he do to make the compost work this time? Mikes says that all Adam needs to make “premium compost super fast” is a large batch of dry, brown autumn leaves, which curbside leaf collectors should be able to deliver to his house. “You really want to mix this stuff,” Mike says, “Don’t layer.” Three quarters of the compost should be leaves that will lighten up the wet, heavy coffee grounds, barley, and chicken bedding, which should be shredded before adding it to the mix. “You could have an explosive compost pile here,” says Mike. The bottom layer could be ready to use in as little as two weeks.

Gourmet herb gardens

Mike spoke with Chelsey Fields, vegetable product manager for The Cook’s Garden, a division of Burpee. Surrounded by intensely aromatic herbs in the studio Mike and Chelsey go over the many kinds of herbs that grow on a remote mountain top in Pennsylvania fed only by spring water and sunlight. Mike remarks that these herbs are intensely fragrant, even more so than his own.

“I’m serious this is much more heavily scented than the lemon scented thyme I have growing at home and you’re saying this is from the this terroir…” Varieties include lemon-scented thyme, pineapple sage, rosemary, tarragon and many more. Lemon-scented thyme is very useful to ward off mosquitoes. You can keep it in pots on your porch or deck or plant it in the garden to help discourage those biting pests. If you are still looking to populate your herb garden this season consider these varieties by The Cook’s Garden.

  • Mike McGrath in studio with Chelsey Fields, vegetable product manager for The Cook’s Garden, a division of Burpee

Combatting weeds organically

Kyra from Claymont, Delaware is prepping her yard for a garden but is having trouble with persistent vine-like weeds. She removed the weeds above ground and even removed the large roots of these weeds beneath the surface. The root segments she’s missed, however, quickly bring these weeds back up to the surface. Last year, her boyfriend sprayed RoundUp which didn’t put a dent in these tenacious vines. To this, Mike warned against using chemical herbicides, saying: “It’s a danger to you, to him and to amphibians. That’s not the right way to go about it. You know, one thing I can tell you from having been the editor of Organic Gardening for seven years, for being on this show for fourteen years, the vast majority of my emails concerning herbicides are that they didn’t work. And now people are ready to go organic and it’s like AH! If only you hadn’t killed all those frogs and toads first!”

Mike commended Kyra for her manual root removal and believes this method will keep 90% of the weeds at bay. To grow effectively in this situation, Mike recommends installing a garden box lined with cardboard to contain her garden and keep the weeds out. Laying down mulch and wood chips outside of the garden box will help smother any new vines that try to emerge.

“The vast majority of my emails concerning herbicides are that they didn’t work. And now people are ready to go organic and it’s like AH! If only you hadn’t killed all those frogs and toads first!”

Mike McGrath

Keeping grass out of the garden

Kim and his wife Pam from Norman, Oklahoma are trying to get rid of Bermuda grass in their large, 3600-foot garden. In response to this conundrum, Mike shares his favorite gardening solution: “When you’re converting something like that, I think you have to have raised beds. You’ll find that you’ll grow twice as much with half the effort.” Mike recommends beginning in one area at a time constructing long narrow beds no wider than 4 feet, lining the beds with cardboard and then filling the beds with a mixture of compost and topsoil. Planting at this elevated level will keep the Bermuda grass at bay and it creates an ideal growing situation with loose, un-compacted soil.

Getting rid of rabbits

Tracey in Glassboro, New Jersey wants to know why rabbits are eating her flowers but are staying away from her neighbor’s flower garden. Mike is quick to diagnose the problem by learning that Tracey’s neighbor has a dog and Tracey does not. Rabbits are very sensitive to the smell of a dog and will avoid the area even if the dog isn’t outside. To keep the rabbits from chowing down on her marigolds, hostas, and petunias, Mike advises Tracey to build a small fence around her flower garden. Since rabbits hop rather than jump, the fence only needs to be between one and two feet high. Other solutions to deter rabbits would be to make her flowers less attractive to eat by spraying deer repellant on her flowers. Or, since rabbits are sensitive to the scent of humans, she could get a bag of human hair from a local barbershop and sprinkle it around her garden. The long-term solution to this problem, however, is to build a small fence.

  • Keeping rabbits out of the garden

    Photo by Flickr user Ross

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