Some of the prettiest plants available can be a nightmare. I’m talking about plants that are so prolific they take over any garden space within a hundred yards. The correct term for these plants is invasive, but unfortunately they are SOLD by nurseries and greenhouses to unsuspecting customers who have the “perfect spot”.
I’ll start with my own worst nightmare: Goutweed (Aegopodium podagraria)
This is a small bed where I put "a couple" of cuttings one year ago!
In my defense, I did not plant this gem on my property—it was already there. But so pretty, with its white edged green leaves and lovely umbrellas of white flowers. It grows in sun or shade, damp or dry, good or bad soil, so—I dug some up and put it in other beds. That was two years ago. At this writing, my property is swimming in Goutweed, a sea of the stuff, with only a few hardy “real” plants peeking through.
Goutweed is sold as a ground cover known as Snow-on-the-Mountain; other names for this obnoxious plant are Bishop’s goutweed and Bishop’s weed. It is classified as invasive in several states (Connecticut, Michigan, New Jersey, Pennsylvania, Vermont, and Wisconsin), and shows wide distribution throughout the Northeast, South, parts of the Midwest, and the Pacific Northwest. It’s only positive attribute, other than a pretty face, is that deer and rabbits do not like it.
Removing Goutweed from your landscape is an almost impossible task. The plant not only reseeds heavily, it spreads by rhizomes, easily filling up two to three feet of garden space in a couple of months. Goutweed is known to be aleopathic, which means it produces toxins to reduce the vigor of its neighbors, much like the black walnut tree. Hand-pulling is ineffective because every little piece of root you leave behind turns into another plant. Chemical control is the method of choice in all the literature; however, given the manner in which Goutweed works its way into your existing plants, using herbicides is not an option unless you’re willing to dig up everything you want to keep before applying the chemical. In some instances, this might be the only way you’ll win the battle.
For the naturalists in the audience, Goutweed has anti-rheumatic, diuretic, sedative, and vulnerary properties and has a long history of medicinal use dating back to the Middle Ages; it is used little by modern herbalists. As its name implies, the plant was used for gout, rheumatism, and sciatica.
Next on my hit list: Anise Hyssop (Agastache foeniculum)
Anise hyssop has gorgeous chartreuse heart-shaped leaves.
I fell in love with this fragrant plant and simply had to have one. Blazing chartreuse leaves in great profusion, a fast grower, and the final display of gorgeous lavender-blue flower heads was my reward. The bees and butterflies loved this plant and I did too. Until the following spring.
I had NO idea that every seed the plant produced would grow! By mid-June, my front garden was filled with at least 20 full-sized plants (2 feet tall). The seeds sprouted in the brickwork, in the crack in the driveway, in the drainage ditch, across the street, in my neighbor’s rock garden. The plants even grow on TOP of the landscape fabric, working their thread-like roots into the mulch.
Anise hyssop is a perennial member of the mint family, but the fragrance and taste of the leaves and flowers is that of anise, or licorice. The plant thrives in full sun, but will tolerate some shade; well drained soil and not much water make this plant an easy grower. This beautiful plant is one that must be watched carefully. Once the flowers are finished: cut. them. off!
Cranesbill Geranium's beauty is short-lived.
Another inherited bugaboo: Cranesbill Geranium
I admit that when I first saw the rocky bank filled with feathery green foliage, I was enchanted. In a few weeks, the plants were covered with lovely bright pink flowers and I thought I had the perfect plant for an area that took brutal sun, no water, and a direct hit from the wind during storms. What I didn’t know was that Cranesbill spreads quickly, pushing its woody roots through the hardest clay soil and anchoring its roots so deeply that pruning shears are required to trim the plant back.
Then the flowers faded and the interesting seed pods shaped like crane bills appeared. Then the foliage grew lanky and dark, shedding leaves and opening up bare spots, into which weed seeds settled and sprouted. In no time, weeds and grasses were growing up through the Cranesbill foliage, defying all attempts to pull them out of the tangled mess below. Shearing tidied up the looks, but the weeds were still there. At the end of summer, the plants rallied briefly, producing a few blooms, then turned dark red-brown and retired for the winter.
Cranesbill is a popular plant in many areas, and it seems to need little to keep it happy. Several descriptions of Cranesbill stated that it helped to keep weeds down, however, my experience is the opposite. If using this plant, be sure to place it in a location where it won’t infringe on other specimens, and be prepared to stay on top of the weeds that take refuge in its tangled body.
My own fault: Morning Glories & Goldenrod
Morning Glories are wonderful in the right spot.
I love the experience of poking a seed into the soil and watching it push through, curling into a tiny two-leaved plant that will end up like the picture on the seed packet. My grandma had morning glories on her back fence and so, when I found myself with a white picket fence, of course I had to have Morning Glories. These versatile climbers are beautiful and today’s varieties come in a glorious array of colors, some even two-tones. But their habit has never changed. They grow fast, grab whatever they can reach, and bloom profusely throughout the season.
Then they drop their seeds. Everywhere. The birds and chipmunks carry the seeds around and drop them. Everywhere. And in the spring, the Morning Glories are—Everywhere.
I don’t know of any way to avoid the dozens of seedlings that come up before you see them. I simply pull the ones that are in a spot not of my liking, and leave the others to grow. I recently found several vines working their way up the branches of a lilac bush. I think it will be lovely when they bloom, and they certainly aren’t going to hurt the lilac.
Goldenrod makes a bold statement in late summer.
The Goldenrod is quite another matter. A year ago, I purchased three plants that grew 5 feet tall and provided us with magnificent sprays of yellow flowers. Butterflies and bees covered these blooms all through late summer and early fall. I’m a big believer in providing food for the birds, so I left the plants as a feast for the winter birds. Big mistake. Goldenrod’s vigor is frightening when it comes to proliferation of seed, with estimates of 20,000 seeds per each flowering stem. I have been pulling these myriad seedlings since early April and there is no end in sight. Too bad, birds. This year, you’ll have just have to visit the feeder.
Many Goldenrod species are considered invasive, and the plant is often confused with flowering ragweeds (Ambrosia spp.) which cause allergy misery. Goldenrod contains polyterpene latex and can cause irritation in individuals with latex sensitivity.
Forewarned is Forearmed
Before integrating any plant into your landscape, learn all you can about it. If you inherit specimens, as I did, be smart (as I wasn’t!) and make sure you want to deal with that plant in the future.
NOW--anyone want to share planting disasters?
(Editor's Note: This article was originally published on June 23, 2010. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)