Anytime is a good time to attack invasive plants, but fall is one of the better and easier times.
My wife, Nancy, and I were driving around coastal Rhode Island a couple of weeks ago, enjoying some scenery before attending a family event. We were amazed how easy it was to spot the Asiatic bittersweet, honeysuckle, multiflora rose, knotweed, Japanese barberry and burning bush in the semi-wild areas near the beaches.
In the fall, leaves will fall from multiflora rose, plus it’ll produce bright red berries, making it easier to spot this invasive plant. Steve Miller/Associated Press
The bittersweet leaves had turned bright yellow, and stood out on the evergreens they were trying to strangle. Honeysuckle and multiflora roses had begun to produce bright berries. The knotweed flowers were everywhere. The burning bush plants were the bright red shade that made them so popular as ornamental shrubs. Upon returning to Maine, we noticed that the bittersweet was still visible, but slightly camouflaged because other leaves were also turning yellow, while the other invasives were still easy to spot.
How you remove invasive plants from home gardens varies, depending on the garden.
Neat traditional gardens, filled with shrubs and perennials, should be weeded every fall. The job can be long and tedious, but it doesn’t take a lot of intelligence. The gardener knows which plants belong there because he or she has enjoyed them all year. Everything else should be pulled out, and if the soil is wet, so much the better – they come out more easily.
A confession here: When weeds are very small, I can’t tell one from another. Nancy occasionally will mock me for this, wondering what my readers would think. I’ve never claimed to be a gardening expert, although I’ve learned a few things over the years. I’m a reporter who gardens and writes about it.
When weeding, I am surprised by how many of the previously unidentified weeds I pull have the tell-tale bright orange roots of bittersweet, even though – after a successful battle for a couple of decades – we have no adult bittersweet on our property, and I haven’t seen much in the neighborhood. It just shows how invasive bittersweet is. Chances are a bird ate some bittersweet berries somewhere else and left the seed, somewhat digested, on our property. I’m not sure what the other weeds I pull up are because they aren’t as distinctive, but I know I don’t want them.
More difficult are the parts of a yard that have always been wild or are being re-wilded. With those, we and other gardeners let plants self-seed, hoping the ones that thrive are native plants, like the black cherry trees we discovered in the wooded area of our garden last summer. That area won’t have any mulched or naked soil, like the formal garden does, so the invasives get to be a pretty good size before we notice them and deal with them.
Treatment differs from plant to plant.
Knotweed flowers in September, making it easy to spot in the fall. “Easy” is not a word you’d associate with eliminating the invasive, though. Photo by By Gl0ck/shutterstock
Bittersweet is fairly easy to pull. I sometimes get orange roots up to four feet long. But keep in mind bittersweet will re-sprout from even tiny parts of the root. Bittersweet seeds stay viable underground for many years. You’ll have to return to the area for several consecutive years to pull more bittersweet. Be sure to get it before the distinctive orange fruit – which contains its seed – appears. And don’t use those fruited vines as decorations.
A few years ago, we cut a lot of honeysuckle in the fall, and painted the cut with glyphosate, or Roundup. That method is still legal in much of Maine but illegal in some communities, including Portland, and the danger of the pesticide has become clearer. Honeysuckle, when large, is hard to pull, as are other invasive shrubs. To get the roots, you have to dig them out – which is tough if there are big rocks or ledge, as in our garden.
The best (and, I think, easiest) method to eliminate honeysuckle is to cut the plant to the ground, and to continue to cut it, year after year, if it re-sprouts. If the sprouts are prevented from growing leaves, which feed the roots, the roots eventually (I hope in my lifetime) will die.
The invasives I find most often in our woods are multiflora rose and Norway maple, because they grow on some of our neighbors’ properties, and the seeds spread far and sprout easily, which explains why they are invasive. I go through the areas in spring, when the multiflora is blooming, and in fall, when the Norway maples are the last trees with leaves. I can tell the Norway maples from red maples, which we encourage, because Norway leaves are larger and they don’t turn red.
I have occasionally found barberry and burning bush, which by the time I notice them are large enough to look like their parents, so I know what they are. I just cut them back.
It’s only infant weeds that confuse me.
Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at: tomatwell@me.com.
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