Invasives
Ousting Prolific Plant Trespassers
Michele MacKinnon
Spring’s arrival may bring thoughts of planting, but it’s an ideal time for unplanting—ousting invasives that arrive like uninvited visitors and overstay their welcome.
What is an invasive plant? To quote Invasive Plants In Your Backyard!, “Non-native invasive or aggressive exotic plants introduced intentionally for their ornamental value, or accidentally by hitchhiking with people or products. They thrive in our growing conditions, and with no natural enemies have nothing to check their rapid spread.” There are 97 species on Connecticut’s official Invasive Plant List and several more pose concern.
“Invasives,” as they’re often nicknamed, serve a purpose. Their roots hold soil in place which prevents erosion. However, if it seems these unwanted plants are everywhere now, it’s another consequence of climate change. They thrive on disturbance and excess carbon in the atmosphere. When storms down trees, invasives are the first plants to repopulate exposed earth, and their vigor often outpaces native plants.
Arm yourself with information.
Choose a disposal method(s) before starting. These Guidelines for Disposal of Terrestrial Invasive Plants offer many options. I build a brush pile in a hidden spot and let material desiccate and decompose. It’s the approach I’ll describe below.
Prepare for battle.
The right tools ease efforts. Gather sharp hand pruners, pruning saws, loppers, and a sturdy tarp. Wear safety glasses. Protect yourself from sharp thorns with impenetrable gauntlet style gloves. Tear-resistant clothing and rugged boots are the fashion choices of determined warriors. Multiflora Rose and Japanese Barberry (often called “sticker bushes'') demand such Personal Protective Equipment. Spray gloves, clothes, and boots with a tick repellent containing picaridin or permethrin.
Enter the fray.
Late winter and early spring, before leaves obscure stems, is an ideal time for this task. Removal after flowering and before seed set is still effective since flowering expends considerable plant energy, impairing the extent of possible regrowth. Start by placing a thick piece of cardboard on the ground. Boxes from large appliances are ideal. The cardboard is the base of the debris pile, forming a barrier that blocks brush from making surface contact and rooting.
Cut them off at the pass.
As you work, drag the tarp along to collect cuttings, including seeds. If possible, tuck the tarp under plants if seeds are present.
Tackle large stands from the outside in. Once reduced to the main or major stems it may be possible to pull or dig less established invasives. The challenge is to minimize disturbance while removing all traces of root. Also, digging may expose seeds and trigger them to sprout. Sawing thick stems at ground level is the next best choice. Sever vines entangled in trees. Inaccessible remnants eventually wither and fall. Transport all debris to the brush pile, ensuring nothing escapes on the way.
Particular cautions
Multiflora rose—step away when cutting arching vines, which may snap back toward your face.
Japanese Barberry—leafs out first in the understory each spring, its green haze revealing the staggering quantity hiding in plain sight. If time is limited, start with barberry removal. It harbors ticks, meaning elimination brings dual benefits. Roots are chartreuse green so finding every scrap is easy.
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Photo: Japanese Barberry removal in author’s garden, after seed set. Photo credit: Michele MacKinnon
Asiatic bittersweet—attack this vine before it sets seeds in late summer. Young plants are common under evergreen trees and can usually be pulled. The telltale Crayola-orange roots are proof of identity.
Defend your victory
Cleared areas must be monitored for several years—an activity equal in priority to removal efforts. Wood chips piled six inches or deeper discourage repeat appearances. Densely sown cover crops, using seed sold by agricultural supply companies, creates deep shade on soil in sunny areas, blocking the light weeds and invasives need to sprout and reverse your toil. Additional chopping may be needed for a few years but the volume of vegetation will be significantly reduced and will weaken plants to a point they generally concede defeat.
The tenacious nature of these purloined plants requires equal determination on your part. It’s a battle worth waging and will allow you to enjoy your property again.
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Resources:
Plant identification apps: iNaturalist, Picture This, Plant Snap, Outsmart Invasive Species
Guidelines for Disposal of Terrestrial Invasive Plants - onsite disposal is recommended
Invasives Guide In Your Backyard - indispensable pictures and facts for Connecticut’s 17 worst invasives and suggested plant alternatives. **Disregard advice on the use of herbicides.**
Invasive Plant Management Calendar - timing and methods of control for Connecticut’s “Top 10 invasives of concern” **Disregard advice on the use of herbicides.**
NOFA Organic Land Care Standards, chapter “Native, Exotic, and Invasive Plants” - organic options for removal and ongoing control
Ecological Landscape Alliance: Invasive Plants - invasives articles including using goats,controlling bamboo, restoration efforts, and more.
Michele MacKinnon, is a UCONN-Certified Advanced Master Gardener, garden educator, and speaker. Contact Michele MacKinnon for information or questions.