I was ignorant when I began to plant my garden and I chose plants on the basis of passion. After a while I discovered that quite a few of the plants I had selected possessed thug-like qualities. You know the ones. They take over, pushing, shoving and choking out the plants that are more graciously behaved. If left unchecked, these aggressive plants can take over an entire border. They remind me of people that talk incessantly, only happy when hearing their own voices. As I age, I want to be with plants (and people) that don’t need to dominate.
Apparently, we all have to go through the phase of falling in love with a plant and then realizing, usually too late, that it’s not the plant we thought it was. My gardening friends all seem to have their own list of thuggish plants. Here are a few of my troublemakers that, if I planted a new garden today, would definitely not be included. Geranium phaeum (dusky crane’s-bill, mourning widow or black widow): I have literally ripped this plant out by the thousands and it still comes up in my garden every year. I even have a hedge of it where I never planted it. Gooseneck loosestrife (Lysimachia clethroides): A gardening friend with a 40-year-old garden chuckled and told me I was “brave” to plant this as we strolled round my garden. Her joke was lost on me. As far as I knew then the plant was well behaved. Her laugh haunts me now. The plant has crashed through my garden like a feral dog on amphetamines. It has a strange pink and white root system that is easy enough to pull out, but if you leave any, and I mean any, part of this root behind it starts spreading again.
After 13 years in this garden, I have a substantial list of thugs. Plants that spread by root are not the only ones that can take over; overnight the “self seeders” will reap havoc on a garden. Each spring I set myself the task of eradicating at least one or two thugs from my garden. Alchemilla mollis (‘Lady’s Mantle’) is certainly no lady. She has taken over hundreds of feet of my borders, inserting her clannish offspring into every nook and cranny. I didn’t mind at first, the sprays of chartreuse flowers are lovely, but I had no idea that this plant’s determination to reproduce included growing in hardpan soil and gravel.
A friend recently defined a bore as someone who cannot go off topic. Plume poppy (Macleaya cordata) is a bore because where it resides nothing else can. Because of this plant’s imposing six- to eight-foot stature, I put it at the back of the border, but in no time it had moved itself to the front. Eventually, I yanked it out of several borders and put it into a hedge of Rhamnus ‘Fineline’ where the wonderful broad leaves look great juxtaposed to the texture of this hedge. Never again will I risk planting it with other plants as it doesn’t know how to behave. Phlox paniculata ‘David’ was great for eight years, no mildew, with sweet-scented clouds of white flowers in August. But the clumps became so large that I had white everywhere and not enough color. Last spring, I dug out massive clumps and dotted them around the edge of the pond to fight it out with wildflowers such as common boneset, asters and flag iris. It will be interesting to see who wins.
Astrantia major (great masterwort) is a European meadow plant and I should have known better, but as it has been appearing in many garden articles and magazines, I guess I was seduced. The white flowering one is the most robust and blooms all summer, but it also chokes out all the plants coming up in ditches and inserts itself into even densely planted areas.
Artemesia ludoviciana (‘Silver King’) certainly “kings” it up in any border. In early spring there is no problem, but turn your back and by midsummer it’s either crawling up the rose bush at a great height or rambling into the garden path, overtaking the lawn. The silvery cut leaf foliage is a nice break from the flowering plants, but left unchecked this plant will turn a border silver in no time. Creeping bellflower ( Campanula rapunculoides) was here when we came to this house. You see it growing in ditches and alongside old farmhouses. I have tried to eradicate this plant so many times from certain spots in my garden, but no matter what I plant in its place it not only reasserts itself, but kills the replacement plant.
The last plant is one of my favorites, Petasites japonicus (butterbur or bog rhubarb). It must have constantly wet soil as it grows. I planted some along my drive and then decided several years later to eradicate it, which only seemed to make things worse. It came back with a vengeance and now covers a very large area along the drive. The first spot I planted it in was along the bottom of a tall retaining wall where the plant was essentially incarcerated. If it grows into the lawn I just mow over it. This is the only way to
really grow this plant as otherwise it continues to spread at a rapid rate, overtaking everything in its path.
The Dutch garden designer Piet Oudolf in his book Designing with Plants has made it his mission to choose good clump-forming perennials that do not move about by aggressive rooting or seeding. In order for his designs to work, such as the High Line in New York City, plants must stay in their place. Oudolf. with his wife Anja, started a nursery in Holland which allowed him to experiment with perennials. One of his requirements when choosing perennials is that they don’t need to be divided. His hard-earned experience can teach us all how to build a foundation of plants that mix well in plant communities rather than lording it over weaker plants. And you may wish to consider ripping out some of the thugs in your garden in order to make room for some more socially cooperative perennials.