You may know Bishop’s Weed, Aegopodium podagraria, a member of the carrot family, as goutweed, ground elder and snow-on-the-mountain. Native to Europe and northern Asia, it was brought to North America as an ornamental and touted as a low maintenance ground cover. Standing up to three feet tall, it has very attractive variegated cream and green foliage that can revert to solid green. It flowers in Queen Anne’s Lace-like umbrels that are charming and long-lasting in bouquets.
Seems harmless enough, doesn’t it? Even desirable?
Here’s the bad news. When it escapes into natural areas, it forms dense, impenetrable patches that displace not only native plants but can infiltrate closed-canopy forests where it out-competes the establishment of native tree seedlings.
It’s an understatement that once established, it’s difficult to eradicate.
That’s because Bishop’s Weed has evolved to be supremely adaptable. It doesn’t colonize only natural areas. I will never know the route it took to my garden, but it’s been here for 40 years. Maybe it came in on a division of a desired perennial I was gifted by another gardener.
One thing I’ve learned is that gardening is like life. It’s all about knowing when to fight, when to give up and when to look the other way.
I will never win my battle with Bishop’s Weed, but for now, I’m not giving up.
I held it at bay until I turned my back on it last year. It managed to stealthily infiltrate a shady area beneath a Magnolia tree.
Last week, I spent several hours digging it out.
A few hours in, I benevolently proclaimed that I would not wish this plant on my worst enemies. After a few more hours of digging, I thought, “Well, maybe I can think of a few……”
Many of my wiser readers would say that eradicating Bishop’s Weed permanently is nothing but an exercise in futility.
I get it. Yet I’ve been gardening long enough to know that using weed barrier fabric to control it is another potential solution that would not solve my problem and is just as futile.
Linda Chalker-Scott Ph.D., Extension Horticulturist and Associate Professor, Puyallup Research and Extension Center, Washington State University, states it best when she likens gardeners to searching for any permanent weed control solution to “the perpetual dieter searching for a permanent weight loss pill. Unfortunately, there is no such permanent fix.”
Weed barrier fabrics were initially developed for agricultural use. It wasn’t long before these fabrics soon found their way into home gardens. Chalker-Scott considers weed barrier fabrics a big improvement over the impermeable black plastics still used for weed control since they are woven to allow water and gas exchange to occur while significantly reducing light penetration. This makes them effective in reducing weed seed germination in areas where soil disturbance would otherwise induce germination of a hot mess of weed seeds.
This all works well at first. However, the fabrics will break down over time, either by physical forces or by becoming clogged with soil particles, reducing their effectiveness and potentially causing further problems.
The truth is that landscape fabrics will eventually provide a great growing medium for all those weed seeds blowing into our gardens or arriving in irrigation water. Weeds will germinate because that’s what they do. They are opportunistic thugs.
Eventually, the pores in the fabric that promised to allow water and oxygen to move through are filled with bits of soil. This results in a mat that is anything but permeable. It becomes a perfect medium for growing weeds. It can also potentially lead to compacted soil, nutrient deficiencies and root rot.
Many gardeners add a layer of mulch over the weed fabric to make it look more attractive. Weeds will continue to germinate and grow above the fabric, even with mulch on top. Their roots can penetrate the fabric, making it difficult to remove them and causing further issues.
Recent research has shown that landscape fabric can be death to microbes, plant roots and animals living in the soil underneath. What’s more, recent research shows landscape fabric reduces carbon dioxide movement between the soil and atmosphere about 1,000 times more than simply applying wood chip mulch would do.
In battling weeds, using a layer of large or coarse wood chips will not only suppress weeds but will allow water and air to move into the soil. A lot more gardeners are utilizing arborist wood chips, which are typically chipped into coarse sizes and often free.
I haven’t used arborist wood chips since I have an almost unlimited amount of hardwood chips that my wood-turning husband produces on his lathe each week. That’s what I dumped on the soil I cleared of Bishop’s Weed. It will work for a while…
Read more about the myth that weed barrier fabrics suppress weeds in home gardens at yhne.ws/landscapefabric.
• Carol Barany and her husband, John, found paradise on 1 1/3 acres just west of Franklin Park, where they raised three children and became Master Gardeners. Contact her at florabundance14@gmail.com.