When it comes to gardening, my own insatiable curiosity is often my worst enemy. I keep trying new plants, either new hybrids or simply plants I’d never seen before. Of course, most of the time the worst that happens is I spend money for nothing on a dud plant, but still, I often do discover some really great varieties. But sometimes the result is much worse.
You see, most of the worst weeds in my yard are ornamentals I planted without having checked them out adequately. Had I looked into them a bit more, I never would have planted them.
Here are a few examples:
The Euphorbia that Ate my Flowerbed
I planted ‘Fen’s Ruby’ cypress spurge (Euphorbia cyparissias ‘Fen’s Ruby’) because it just looked so cute in the nursery, almost like a little purple conifer with contrasting chartreuse flowers. But what was I thinking when I planted it? I knew that several (but not all) spurges (euphorbias) were invasive, but this one was so tiny and dense, how could it possibly do any damage?
12 years later, I’m still fighting it. The plant spreads thanks to underground stolons that head off in all directions. And to be honest, it’s not even all that attractive, because its pretty spring coloration doesn’t last, the leaves turning a more boring glaucous green for the rest of the summer. Worse, when I yank it, it releases a sticky, poisonous latex you must not get into your eyes. In spite of my efforts, every year its spreads further and further. I may have lost the war against this one!
Self-Sowing by the Thousands
‘Ravenswing’ cow parsley (Anthriscus sylvestris ‘Ravenswing’) is in itself totally charming. And I see it mentioned recommended on lots of Websites as a great garden plant. With its glossy, deeply cut foliage in a superb dark purple, almost black, it looks like a black fern… when it’s not in bloom, at least. Of course, the umbels of tiny white flowers, reminiscent of those of its cousin, the wild carrot (Daucus carota), prove it isn’t a fern (ferns don’t bloom), but they do make a nice contrast with the foliage.
It didn’t take me long to realize I’d made a mistake in planting this one. The following spring, hundreds of seedlings popped up in my garden, about half with the same shiny dark purple leaves as the cultivar, the other half with plain green foliage. (Obviously it does not come totally true to type from seed).
Subsequently I learned that the secret to keeping ‘Ravenswing’ under control is to remove the flowerheads before they go to seed, because the plant itself never suckers: it only spreads by seeds. Besides, removing the flower stalks before they go to seed helps extend the life of this plant which is essentially a biennial. If it doesn’t produce seed, it will tend to sprout anew the following season.
But it’s too late for that now. Pretty clearly, the seeds can live for many years, because even if I pull out or cut back the seedlings as soon as I see them and never let them bloom, new seedlings grow back every year.
I intend to keep fighting this one: I don’t want to be accused of having introduced this invader to my region (the green form is known to be a noxious weed!)… and self-sowing plants get around much faster than stoloniferous ones!
An Aggressive Invader
I must admit that I was still a young and naive gardener when I planted my first plume poppy (Macleaya cordata). I don’t think I was yet 25, so that would have been nearly 40 years ago. I simply assumed that garden centers would never sell weedy plants, that if it was being sold, it had to be something desirable. I’ve since learned otherwise.
Some people actually like plume poppy. Its proponents claim it’s not all that invasive and that it’s easy to control. If so, how come every time I see it in a garden, it seems to have pretty much taken over? And it’s a big bruiser of a plant, too, about 8 feet (2.5 m) high, big enough to crowd out the competition.
Part of the difference in attitude might be that it is less invasive in heavy soils. Well, I planted mine in practically pure sand. The plant spread from one end of the flower bed to the other, about 20 feet (6 m) in just two years. The whole bed turned into a macleaya jungle, and it would have taken over the lawn too if I didn’t mow it regularly, chopping off the sprouts as I went. When you try to pull it up, it covers you in sticky orange sap that stains everything. Worse yet, all that effort is for a plant I honestly don’t even find all that attractive.
I solved this problem quite promptly: I moved and left it to the new owner to handle.
I knew that common false spirea (Sorbaria sorbifolia) was invasive and I would never have planted it on purpose, but I was done in by a lying label.
You see, I was looking for Kashmir false spirea (S. tomentosa angustifolia, syn. S. aitchisonii), common false spirea’s more restrained cousin. This species doesn’t sucker and is not invasive. In fact, that’s its main selling point: it’s just as pretty as common false spirea, but it stays put! The two species pretty much resemble each other (Kasmir false spirea has somewhat finer leaves, though), and before I realized the error, the damage was done. I’d let the devil loose in my backyard!
The problem wasn’t obvious at first: like many woody plants, the mislabeled common false spirea took a few years to settle in. Then suckers began popping up… everywhere. This shrub made a beeline for the fence and moved into my neighbor’s yard from which it now regularly makes forays into my garden. It follows the fence for a good 50 feet (15 m) and every year I cut back and pull out hundreds of suckers that dare cross the fence back into my yard.
The phenomenon of mislabeled plants is unfortunately very common in the horticultural world. Some nurseries just don’t seem to give a damn about what the label says as long as the plant sells. You can see where you could make a lot more money selling the prolific common false spirea labeled as the slow-to-multiple Kashmir false spirea. But I don’t want to make it sound like all nurseries do this: many take the correct identification of their plants very seriously.
I really don’t have a solution for this problem except to always complain when you find a mistake. It’s not your local garden center that is to blame (usually), but the wholesale nursery that shipped out the plants with the wrong labels. I like to think that if enough people complain about getting the wrong plant, it will make a difference.
Sold the Wrong Knotweed
The false spirea incident was not the only time I got into a pickle because of a mislabeled plant. There was also the case of the mislabeled Japanese knotweed and that could have been much, much worse!
Japanese knotweed (Fallopia japonica) has such a bad reputation as an invasive plant that the species itself is rarely seen in plant nurseries. It’s considered one of the worst weeds in the world! But if the species itself is highly invasive, there are a few ornamental cultivars that don’t sucker or only do so to a very limited degree. The variegated cultivar, F. japonica compacta ‘Milk Boy’ (apparently the correct name for ‘Variegata’), for example, is easy to control and fairly widely available.
But I wasn’t looking for ‘Milk Boy’. I wanted ‘Crimson Beauty’, an extraordinary giant perennial with bright mossy red flowers I first saw at Longwood Garden decades ago. It is non-suckering and produces a huge shrublike plant with flowers that last 3 months. Really, I have rarely seen such a beautiful perennial! But I never seemed to be able to find it in nurseries, not even in catalogs, at least, not in Canada (for me, ordering from the US is a major complication). Then, in 2003, I finally saw one in the mail order catalog of an Ontario nursery and of course of course sent for it.
It didn’t bloom the first year, but when the second year came around, the flowers were not red, but white. I thought maybe they’d turn red over time, but no such luck. Then I figured (wishful thinking!) that maybe the red flowers only appeared when the plant was mature. But by the third summer, I realized that I had made a huge mistake, that my plant was not the non-suckering ‘Crimson Beauty’, but the species. I knew this for sure not just because of the still-white flowers, but because suckers started popping up everywhere, even 3 or 4 feet away from the mother plant.
I’ve been known to put things off, but my entire yard was at stake here, and I didn’t hesitate. I dug up the mother plant (quite a struggle, as the roots were incredibly deep), then hacked out all the thick rhizomes I could see as well, pretty much trashing a huge section of garden. Soon new shoots appeared: strong, dominant shoots as thick as my thumb that seemed to be saying “you’ll never be able to stop us”. But I cut them to the ground. And cut back the new sprouts that followed as well. And their replacements. Each time I cut them back, the next generation had thinner, shorter stems. By year 3, the invasion was nearly over. Still, the occasional stray sucker came up in year 4 and even a few in year 5. None appeared in year 6: I had succeeded in eliminating Japanese knotweed from my yard: not many gardeners can make that claim.
I did contact the nursery that sold me the plant and they apologized. It wasn’t one of their plants, but a plant they’d bought in under the name ‘Crimson Beauty’. I know that sort of thing happens, but it’s annoying to have had to put 5 years of efforts into correcting someone else’s mistake.
Anyone can make the mistake of buying an invasive plant by accident. After all, the fact that the plant is a weed is not the kind of detail that the seller ever mentions on the label! But don’t do as I did and plant an unknown plant without checking into it. The Internet can be a great tool for that sort of thing and it takes only minutes to do a reasonable search. You won’t want to be struggling today to control a plant you put in years before.
My yard is full of out-of-control plants other people planted: buttercups, Spanish bluebells, daisy, alchemilla, lamium, quince, English ivy… some of them given to me by my mother-in-law, some planted by neighbours or the previous home owner. Add to that the horsetail, and I have some tough challenges, weedwise. It makes me feel like the garden is not my own.
I certainly understand that!
Maybe you would have some advice for me. I have a 2 acre space where I will be building an orchard of fruit trees and berry bushes. It is almost pure sand. Technically it is “loamy sand” but it feels/acts like beach sand. The area is very hot and dry in the summer. We are zone 4a and get average rain/snow of 30-34” per year. The orchard area is surrounded by 11 acres of native upland prairie on one side, grass on one, and pine/oak/aspen forests on the others.
I am looking for a ground cover to grow in between my trees and berries (I will also mulch around each plant) that can handle dry sand, hot summers, and cold long winters. I will be irrigating the orchard plants by drip but not in between. I would prefer it to grow quickly but be easy to remove if it were to escape into the forests or prairie – or if would try to overtake the orchard plants.
I would like to be able to walk on the ground cover without damaging it. It doesnt have to be “barefoot” walkable. Being able to survive mowing at a high level (for weed management) would be a plus. If it flowers (especially in spring or fall – which are my tough bee seasons) that would be great, but we do have forests and prairie for the bees so it is not necessary. Any advice?
The “walkable” bit is always the hardest to satisfy. So many groundcovers really don’t like foot traffic. Still, you won’t be walking on the same spots all the time and even ground covers said not to tolerate foot traffic ought to be able to cope with that.
Just about any low-growing ground cover will survive high mowing: if you cut off a few tips, so that’s not a problem.
That said, I suggest looking mostly at drought tolerance in summer, plus cold resistance (you mentioned zone 4a). Most drought-tolerant plants will take hot summers. Look here and see what you find: https://laidbackgardener.blog/2017/04/26/groundcovers-for-sun/
Heights (important for your mowing) aren’t mentioned, but you could pick out a few plants that seem suitable and check on that.
Ah, in my case it would be Lirope and ribbon grass. The ribbon grass was a gift that kept on giving and I’m still pulling out a few strands each spring. The Lirope did more than annoy me after it kept spreading, it sent me to the pain management clinic for several months.
Ugh! Yes, one must always beware of gift plants: they tend to be invasive ones!