How to dispose invasive plants

If my latest Winter Review post, Are you invasive species savvy? did not offer ample links for learning about Connecticut’s invasive plants, check this guide. Once you can identify invasive plants, and likely have learned your landscape contains at least one, it’s time to learn how to properly dispose invasive plants.

Connecticut’s DEEP and the University of Connecticut developed Guidelines for Disposal of Terrestrial Invasive Plants. Not all invasive plants are treated equally when it comes to disposal. The guidelines noted above are the most comprehensive I’ve found to date and provide valuable information on the proper disposal of terrestrial invasive plants.

Based on these guidelines and my own experience, these are the most important rules to follow when removing and disposing of invasive plants from a home landscape.

Rule #1: DON’T ADD INVASIVE PLANTS TO YOUR COMPOST PILE! This refers to the compost you intend to spread back into planting beds. Home compost piles often don’t get hot enough to destroy all seeds/roots. When spreading home compost to planting beds you don’t want to also spread still viable seeds/roots from any invasive plant.

Rule #2: R-read Rule #1.

Rule #3: Read the guidelines, print them, bookmark the link, and refer to the guidelines regularly.

Rule #4: Repeat Rule #3.

As an Organic Land Care Professional caring for home landscapes, I do not advocate the use of chemicals for control of invasive plants. Instead, I suggest vigilant observation for invasive species, followed by cutting, pulling, smothering, and/or burning, followed by vigilant observation and re-cutting, re-pulling, re-smothering, and/or re-burning as needed.

OLYMPUS DIGITAL CAMERA Dealing with invasive plants is not sexy, but it is an oh-so necessary part of gardening in today’s world.

Catching invasive plants when they are still young, removing them, and regularly rechecking for re-sprouts, is the best control method and the easiest way to prevent invasive plants from taking hold. I do invasive plant patrols on our nearly three acres of home gardens and woods in early spring, late spring/early summer, mid-summer, late-summer, and before a killing frost. These patrols have proved to be as important as weeding in my cultivated beds.


For small, invasive woody shrubs, vines and trees, I use the pull-out-all-roots and leave-to-dry method. The key is in getting all the roots. I often leave the pulled plant to dry atop a fallen tree , then target the areas where invasives were found for continued re-checking for new sprouts. This is particularly important for Japanese barberry, as it aggressively regenerates from the slightest piece of root left in the soil.

OLYMPUS DIGITAL CAMERA When I spot a large number of newly sprouted invasive plants – think Oriental bittersweet seedlings that sprout each spring under trees after birds have deposited partially digested seeds during winter roosting visits to the tree’s upper branches – I collect pulled seedlings in a plastic bag (I reuse large plastic bags from prior mulch, compost, or soil amendment purchases). Letting bagged seedlings bake in the sun for a week or so kills seeds/roots then the bags go into the trash.

This is my preferred disposal method for Japanese Stilt Grass seedlings and plants (left photo), bittersweet seedlings, garlic mustard, and any small weed in flower.

After weeding out young invasives – or any weeds – be sure to follow the standard good-gardening practice of covering exposed/disturbed soil with some sort of mulch.

Larger invasive plants, such as bittersweet vines that have climbed into trees, can be cut to prevent further growth, leaving cut remains on site to dry. But cut trunks/stems must be monitored for re-growth. And … if the invasive has produced flowers or seeds, the area must be regularly checked for newly sprouted seedlings. Non-flowering, non-seeding woody plant material can be chipped, left in place,  or used to create a brush pile as habitat for woodland birds and creatures.

Japanese barberry requires repeated monitoring and managing of regrowth. This video shows how torching is used for Japanese Barberry control, but this method requires specific precautions and is not recommended for everyone.


Courtesy of the Univ. of CT Extension System, CT Agricultural Experiment Station

The proper management and disposal of invasive plant material is best determined by the location, age, size, flowering status, and reproductive ability of each invasive. To keep invasive plants from spreading and overtaking your landscape you need to make monitoring and control a regular gardening task … just like weeding.

Invasive plant control can seem a daunting task, but keep at it … the more diligent you are in controlling invasive plants in your landscape the less time you will ultimately need to spend controlling them.

February 23 to 28, 2014 is National Invasive Species Awareness Week … take this opportunity to learn more about invasive species in your area.

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Winter Review: are you invasive species savvy?

Winter is the ideal dream time for cold-climate gardeners, but it’s also a perfect time to review good gardening practices and increase your gardening knowledge. For this Winter Review we’ll examine invasive species.

February 23 to 28, 2014 is National Invasive Species Awareness Week. Since winter snow covers most of Connecticut and cold temperatures continue to keep most gardeners inside, now is a great time read 10 Ways To Observe National Invasive Species Awareness Week.

There are many ways to prevent spreading invasive plants and creatures that seriously impact native species:

  • cleaning hiking boots, waders, boats/trailers, off-road vehicles, and other equipment or gear on which an invasive seed, plant, or creature may hitch a ride;
  • not dumping aquariums or live bait into waterways – something I thought was a no-duh;
  • using hay, mulch, and soil designated weed-free;
  • and planting only non-invasive landscape plants.

But, there are other means by which invasive plants and creatures spread: seeds and plant pieces may hitch a ride on gardening and lawn mowing equipment; potentially invasive weeds and seeds may arrive in nursery plants; and gardeners can inadvertently transport potentially invasive species by sharing plants from yard to yard or region to region. Even firewood can hide invasive insects – are you aware of the Emerald Ash Borer-caused ban on moving wood from ash trees and firewood out of New Haven county?

To become invasive species savvy, gardeners, homeowners, landscape workers – in essence everyone – must know where to find solid, trustworthy information. In Connecticut, start with

For a plant to be listed as invasive in Connecticut, it must be non-native and harm the environment, human health or cause economic harm in minimally managed areas (woodlands, waterways, open spaces) through its ability to establish and rapidly grow in a wide variety of conditions, reproduce prolifically, disperse over wide areas by vegetative fragments and/or seeds, and lack the growth and reproductive controls evident in the plant’s native regions.

A few of Connecticut’s most prolific terrestrial invasive plants include


Oriental bittersweet (Celastrus orbiculatus), as young plants and roots above;



Japanese barberry (Berberis thunbergii) as young plants, above, and en-masse, below, in early spring;



and Japanese Stilt Grass (Microstegium vimineum) as it emerges in early summer …


and shortly before it goes to flower and seed.



Connecticut is also plagued by Autumn Olive (Elaegnus umbellata), Garlic Mustard (Alliaria petiolata), Japanese Knotweed (Polygonum (Falopia) cuspidatum), Multiflora Rose (Rosa multiflora), Burning Bush (Euonymus alatus), and multiple other trees, shrubs, annuals, perennials, grasses and aquatic plants.

The Invasive Plant Atlas of New England is another great resource for New Englanders. Those in other regions should research the invasive species information provided by their state.

Learning about invasive species is an ongoing process … after gardening for more than three decades, I’m still learning. Every region is different, but learning what is already determined to be invasive in your area is the FIRST STEP in becoming invasive species savvy.

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Connecticut’s Invasive Plants

This is a re-post from October 2012, but the information is still valid and important.

What a gardener refers to as invasive might really be no more than a garden thug – a plant that doesn’t understand how to play nicely with its neighbors and aggressively crowds other plants. Garden thugs may be a pain in the root to neighboring plants, or a pain in the gardener’s back – or more southerly bit of human anatomy – but a plant thug may not pass the nine point test required to be named a Connecticut invasive.

To date, 97 different plant species have been added to the Connecticut Invasive Plant list. Each meets the following criteria – all nine of them. The plant

  • is nonindigenous to Connecticut – it was not here before European colonization;
  • is naturalized or has the potential to become naturalized – it’s happy here;
  • has the biological potential for rapid and widespread dispersion and establishment – it can spread easily;
  • has the biological potential for excessive dispersion – it can spread excessively;
  • has the biological potential to exist in high numbers outside of intensely managed habitats – for example, in woods, fields, wetlands;
  • it can be found in wide regions or in particular habitats within Connecticut;
  • it has grown into large stands;
  • it can out-compete other plants;
  • and, it has the potential for rapid growth, high seed production and dissemination, and establishment in natural communities.

This photo of Japanese barberry overtaking a forest floor is a good example of a Connecticut invasive.


Japanese barberry, garlic mustard, Oriental bittersweet, Russian and Autumn olive, Winged euonymus, a.k.a. burning bush, ground ivy, many honeysuckles, moneywort, Japanese knotweed, multiflora rose and sheep sorrel are some of the invasive plants common to Connecticut gardens, as is mugwort, the most recent addition to the Connecticut Invasive Plant list. (The October 2012 update lists mugwort. As of the date of this post, the October 2011 online version, does not.) Many of these plants are so invasive they are found in every Connecticut county.

Of the 97 plant species considered invasive in Connecticut, 80 are illegal to import, move (unless for research, control, or education purposes), sell, purchase, transplant, cultivate, or distribute, according to information provided to attendees at the Invasive Plant Symposium held October 25, 2012 at the University of Connecticut. Notice I said just 80 of Connecticut’s invasives are prohibited. This means 17 can still be sold and purchased, planted and distributed in spite of their invasive label.

Becoming familiar with the Connecticut Invasive Plant list is one way for Connecticut gardeners to garden thoughtfully. It’s much better to identify a plant as invasive before giving it a chance to do its invasive thing in your garden or on your property. It’s also valuable to know how to recognize invasive plants when they first show themselves. Eradication is so much easier when plants are young.


Update: read more about how we control Japanese stilt grass.

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