Invasive Plant Management
Making a plan to remove the invasive plants on your property is arguably the most important thing you can do to preserve habitat, because once that habitat is destroyed, you will never be able to fully restore it.
The term "invasive" has legal meaning. It is defined as a non-native organism that, when introduced to the ecosystem in question, causes or is likely to cause economic or environmental harm or harm to human health. Therefore, by definition native plants are never invasive in the area where they evolved. However, they can be "aggressive" or "assertive" in a garden setting! To avoid confusion, plant-people restrict the use of the word "invasive" to non-native species that meet the definition above.
If a species is causing environmental harm, it obviously should be removed if at all possible (and never planted.) Do not be distracted by the term "naturalized." A non-native plant may have become established in an area but at a low enough level to not cause noticeable damage. Because it did not evolve with all the intricate flora-faunal relationships that take thousands of years to develop, it is unlikely to be contributing much of meaning to an ecosystem, but if it is not causing damage by displacing native plants, perhaps because it is small and sparse in numbers, it may considered relatively neutral. But don't let anyone make an invasive plant sound nice by calling it "naturalized."
Mini-grants for communities
The Audubon-at-Home program has been given a grant from the Fairfax Tree Preservation and Planting Fund to divide among ten lucky communities for rescuing trees that are being threatened by certain invasive plants. If you live in a Fairfax County community association or faith community with common open space in need of tree rescues, you can read a general outline and request a pre-application visit here:
Start with an inventory
Every site is different with a different mix of plants with differing densities of infestation. Furthermore each owner can have different priorities and objectives. Start with some kind of inventory and preferably a map of the invasives. There are many people who can help you identify your plants, including our urban foresters and Audubon-at-Home volunteer ambassadors. For a commercial site, we have volunteers who can do a site visit with the lawn-and-landscape company to identify the invasive plants.
Protect the canopy
Vines that bring down the canopy are a top priority. Once you lose canopy it takes a long time to recover it and light comes to the forest floor and other invasive plants explode.
On the one hand, it is good to remove invasive trees early, especially Tree of Heaven - removing that now may slow the spread of the horrible Spotted Lanternfly that has recently arrived in Virginia. On the other hand, if you take away too many trees at once, you open up the canopy and make it more vulnerable to invasives, so it may be best to get rid of Tree of Heaven first but remove other invasive trees incrementally.
Suggested Priorities List
If you are dealing with a large number of invasive plants, you probably can't work on them all at once. Below is an example of a plan to prioritize your efforts.
Give priority to
Invasive vines threatening trees
New arrivals – eliminate uncommon invasives and new arrivals before they can get a real foothold. Go for eradication.
Protecting high-quality habitat. If that habitat is surrounded by invasives, work outward from there. Another way to put that is that if you have an infestation too large to handle all at once, work from the outside in.
Special needs and circumstances – there is reason to believe that taking out all Ailanthus or most of it should be a top priority to slow down the Spotted Lanternfly invasion. There may be other cases, like protecting some special ecosystem or rare plants that also require a high priority. Plants that are dangerous to the public could also become a priority.
Most damage – what invasive plants are causing the most damage
What is feasible – where can applying resources actually make a real, lasting difference
Shoot on sight list – which plants can we treat and get to the point where they are rare enough that we can actually stop what we are doing every day and go take them out whenever we find one. Trees and some less common plants are the first ones you are likely to get onto this list.
If you can address all the above and still have capacity left to do more, then you can consider other factors like aesthetics, public reactions, public access, impacts on neighboring properties, and proximity to spreading vectors like public trails, streams that flood, etc.
A whole other set of criteria may apply if you have bodies of water and aquatic invasive plants to deal with. This can get into impacts on public recreation and public safety.
In almost all cases, controlling invasives will be a multi-year process. For example, expect three years of treatment for most invasive vines and five years for wisteria.
Consider the timing
WInter is a great time to work on many invasive plants (or to hire landscape workers to do the job). Summer may be problematic because of heavy growth, ticks, and poison ivy, not to mention the heat.
It's helpful to kill plants before they go to seed. Removing smaller plants means there is less bulk to deal with but in some cases may give them more time to grow again and form fruit that year.
Some plants need to be killed BEFORE cutting them down. Simply cutting them may cause them to send up a hundred new plants from the roots. Tree-of-Heaven is a classic example.
The effect of herbicide applications is highly dependent on timing. You must carefully research the timing for each species. Find details on the Blue Ridge PRISM website.
To stabilize a steep slope after removing invasives such as English Ivy, you can put down a jute fiber net made for this purpose.
Don't kill the native vines!
The berries of native vines are an essential food source for birds, with the right nutritional content timed to their migrations. They do not damage the trees they are climbing on. Examples are native grapes, Virginia Creeper and Greenbrier, but there are many others. Like most natives, some introduced species such as English Ivy climb straight up. But if the vine twists round and round a tree and squeezes the tree as it grows, it is probably an introduced species (an exception is the American Wisteria).
There are many organizations that need volunteers to do this. These groups are well set up to train you and ensure safety. Events take place year round and always need more help.
See the list on the
Note: In Virginia, only Certified Pesticide Applicators may
use restricted herbicides (glyphosate and triclophyr are not restricted)
use herbicides for hire
use herbicides on government-owned land or public access land of greater than five acres.
Anyone using herbicides, whether for pay or for free, must follow every instruction on the label about how to apply them, in what concentration, on what plant, and using which personal protective gear. "The label is the law." Some products must not be used near water bodies.
Invasive Plant Removal Contractors
We are listing companies for your convenience, but aren't endorsing any of them.
Lamb Mowers Located in Fairfax.
More typical removal methods:
Invasive Plant Control, Inc
Tennessee (but they serve Northern Virginia)
Land + Forest Conservation Co
Conservation Services, Inc.
Eastern Forest Consultants
Virginia Forestry and Wildlife Group
Including Forestry Mulching:
Blue & Gray Contracting
Grasshopper Tree Service
Miscanthus (Chinese Silvergrass)
Before/after Japanese Barberry removal
WIneberry: Before and After
W&OD Trail: Japanese knotweed, porcelainberry, Japanese stiltgrass, wineberry, garlic mustard, Hairy Bittercress, multi-flora rose, mile-a-minute, oriental lady’s thumb, and various other Asian ornamental grasses that have escaped from people’s yards.