There are lots of wonderful plants out there, but on the flip side of that coin, there are also plenty of thugs. Many times invasives are attractive to new gardeners because they are easy to grow.
Spring is plant swap season, and because it’s easy to unknowingly bring a beast into the garden, many of which regularly show up at such events, we asked some of our most talented local gardeners, nursery owners and landscape designers what they would NEVER plant. Some of the selections are invasives, and others have been rejected due to poor performance in the garden.
These experts represent more than 100 years of experience here, and they might just save you a lot of headaches.
Karen Atkins, a garden designer formerly from New Brighton who currently designs gardens in Ohio, offers her list of bugaboos.
“Mallows. They are gorgeous and long blooming but quickly take over the whole bed with multiple tap roots to China. You will never get rid of it.
“I would never use a variety of iris that does not rebloom in the fall. If you buy varieties that don’t rebloom you are needlessly forfeiting flowers.”
And, finally, “Never buy a ‘Knock Out’ rose. To make it disease resistant and pest resistant they gave up fragrance, habit and form, [the thing] that makes roses worthy of fetishizing.”
Bernadette Kazar, who has a beautiful plot in Heidelberg, shares her least favorite plants.
Rose of Sharon — “Not graceful, and the flowers fall off too fast (not to mention that it reseeds the entire universe).”
Magnolias — “They start to bloom when we have nice weather and, boom, a cold snap and they are done, brown blooms everywhere.”
Peonies — “Even though I have them, the flowers are top-heavy and flop to the ground when it rains, even if you tie them up. They also bloom all at once, and the show is over.”
Laurie Curl, owner of Hahn Nursery Garden Center & Greenhouses in Ross, says that the business avoids selling anything that’s on the Pennsylvania invasives list, which can be found here.
She particularly cautions against bamboo, saying that the nursery only sells clumping varieties and counsels buyers about how to plant it correctly to avoid planetary invasion.
Two other trees she warns against are the once ubiquitous ‘Bradford’ pear tree, saying it has weak wood and is too prone to splitting, and silver maple. She also advises avoiding trees that are marketed as fast growing.
“We know that fast growers tend to be problematic down the line,” she says.
Richard Liberto, a gifted garden designer, owns Liberto Landscape Design on Troy Hill. An overachiever, he provided us with five plants he would never use and then suggested replacements.
Japanese barberry — Due to its invasive habit and lethal thorns this outdated shrub should be replaced by some of the red-leafed cultivars of weigela, ninebark or ‘Double Play’ spirea.
Burning bush — This is another invasive that is planted all over the place, and Liberto says there are great substitutes for it. He suggests ‘Crimson Comet’ Button Bush, with fiery red leaves in the spring, repeated again in the fall, plus white flowers that attract pollinators. Itea ‘Henry’s Garnet’ or ‘Arctic Fire’ shrub dogwood with beet red stems in the fall/winter are tolerant of wet areas.
Golden honey locust tree — “Talk about a throwback from 1960s urban redevelopment,” says Liberto. “It’s a tree that has served its purpose, but it’s time to move on.” Citing tiny leaves that drop and blow around, good replacements are ‘Robin Hill’ serviceberry, Krauter’s purple leafed plum, or ‘Yoshino’ cherry or ‘Royal Raindrops’ crabapple that has bright pink flowers with persistent fruit and strong disease resistance.
Arborvitae — “In addition to being a deer salad bar,” Libeto says, arbs are ubiquitous. He suggests several overlooked evergreens. Vanderwolf pine (100% deer resistant and quite beautiful), ‘Paul’s Select’ blue spruce or a cultivar of the native Juniperus virginiana called ‘Taylor.’
Miscanthus ornamental grass — Who knew this Asian species, first seen 30 years ago, would become so invasive. Of course deer hate it, but they also hate native switchgrasses, also known as Panicum species. Try Panicum ‘Cloud 9,’ ‘Dallas Blue’ or, Liberto’s personal favorite, Panicum ‘Shenandoah.’ He also loves little bluestem grass ‘Standing Ovation,’ calling it a must-have.
My garden rejects include:
Houttuynia cordata or chameleon plant — If you see this plant, run the other way. It is highly invasive. You can’t dig it out because it will proliferate from the smallest piece of root that is left behind. The brightly colored leaves of this low grower look festive, but don’t let it draw you in. The only real way to get rid of it is to get a divorce and start a new garden.
Lamium maculatum or spotted dead nettle — Sold as a ground cover, it does cover ground. Rapidly. It also jumps around the garden at will, popping up in places where it was never planted. Constant weeding sort of controls it. Do yourself a favor and avoid this one.
Porcelain berry or Ampelopsis brevipedunculata — Boasting beautiful blue berries, this pest-resistant vine will tolerate crummy conditions. The very reason people plant it is the reason it’s invasive. Avoid it.
Susan Banks was a copy editor at the Pittsburgh Post-Gazette who was on strike from October 2022 until she retired at the end of 2023. Email her at klebergardens@gmail.com.