5 Invasive Plants You Need to Tackle This Winter – Remove Them Now Before They Take Over Again
Discover which invasive species are simpler to eradicate in winter, and their safer alternatives
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Taking over your garden, overpowering other cherished plants and even damaging local habitats, invasive plants can cause a surprising amount of trouble. Controlled by regular pruning, thorough weeding and in some cases, the use of chemicals, you will want to keep the upper hand if you have any vigorous species in your backyard. And late winter is the perfect time to do that.
Some invasive plants are best removed entirely and are more easily identified and eliminated during the colder months.
Which Invasive Plants Are Easier To Remove In Winter
Invasive plants can include everything from bulbs and climbers to shrubs and even ornamental grasses.
When it comes to removing these in winter, the dormant period of November through to March is generally the window.
So, if you are reading this in late-winter, you will want to act swiftly to benefit.
Japanese Spurge
Pachysandra terminalis, or Japanese spurge as it is more commonly known, is a reliable evergreen groundcover plant. Often considered one of the easiest ground cover plants to grow, it is favoured by garden designers for its ability to tolerate partial to full shade, especially under trees.
Furthermore, Japanese spurge develops small white flowers in spring, which can look particularly effective when grown en masse. However, it is a vigorous plant and can rapidly spread via its rhizomes.
In cases where it needs to be eradicated or its spread reduced, Andrew Bunting, Vice President of Horticulture at the Pennsylvania Horticultural Society and author of The Plant Lover's Guide To Magnolias (available on Amazon), suggests that ‘this evergreen, ground-covering perennial is easy to identify and remove in the winter.’
To remove Japanese spurge in the gardens I have managed, I have found that digging it up, either using a hand trowel, border spade, or my prized Hori-Hori knife in winter when the ground is moist, but not frozen, makes it easier to remove along with its rhizomes.
As an invasive specimen, care should be taken to dispose of it carefully rather than adding it to a home compost bin.
Often cited as the most versatile gardening tool, Hori-Hori gardening knife can be purchased from Burpee.
For something less vigorous, you could try wild ginger, Asarum canadense, which, although spreading in nature, is far slower.
Andrew Bunting is Vice President of Horticulture and leads the utilization of planting and design to promote environmentally sound gardening practices at the Pennsylvania Horticultural Society. Prior to arriving at PHS, Andrew worked at the Chicago Botanic Garden, Chanticleer Garden, and the Scott Arboretum for a tenure of 27 years, and has received many commendations for his work. In 2015, Andrew published his first book, The Plant Lover’s Guide to Magnolias.
Oriental Bittersweet
Celastrus orbiculatus, or Oriental bittersweet, as it is popularly known, is a deciduous vine that is considered invasive in many states.
Related to, but more aggressive than the American bittersweet (Celastrus scandens), Oriental bittersweet is a vigorous climber and can grow more than 30 feet high, smothering trees and shrubs in its wake. Furthermore, it spreads rapidly through natural seed dispersal and via its rhizomes.
When it comes to invasive plants that are easier to remove in winter, Karen Daubmann, Director of Garden and Programs at Massachusetts Horticultural Society, says: ‘Late winter is a great time to focus on vines and thickets. The lack of leaves makes these tangled and unruly vines easier to identify and snip away.
'Tackling vines in the winter ensures you’re only cutting the bad stuff and leaving the plants you wish to protect. You can usually tell which vines and thickets are invasive even without the leaves since they tend to be unruly and pervasive.’
Karen suggests: ’Use loppers and hand pruners to cut the undesirable plants close to the ground. If you leave a stub you can put a piece of ribbon around it and come back to pop it out by the roots in the spring when the ground thaws, or you can leave the stub and monitor the plant regularly to see if it has resprouted and grown – you’d want to keep it in check, not allowing it to flower and seed again.'
For a safer alternative to Oriental bittersweet, coral honeysuckle (Lonicera sempervirens) is a great choice.
Ideal for arbors or trellises, its red tubular flowers are known to attract hummingbirds and pollinators. Coral Honeysuckle Live Plants are available to purchase from Amazon.
Karen Daubmann is the Director of Garden and Programs of Massachusetts Horticultural Society (MHS). For over 25 years, she has led and contributed to the success of many great gardens across North America, including New York Botanical Garden, Phipps Conservatory and Botanical Gardens, Olbrich Botanical Gardens and Longwood Gardens.
Burning Bush
Loved for its almost-neon pink-red autumnal foliage, Burning bush, Euonymus alatus, is an ideal fall shrub for privacy.
Unfortunately, it is also known for its aggressive nature. Spreading by wildlife and birds transporting its seeds, new plants grow and sucker and form dense thickets that can overtake other plants and ecosystems.
With regards to its removal, Andrew reports, ‘This large shrub is characterized by winged stems, which are easiest to identify in the winter. The plants can be cut at the base; however, removing the roots as well is ideal.’
Classified as invasive in many US states, it requires controlling and can be removed at any time of year. However, when the ground is moist in winter, digging up its roots and new suckers is certainly easier.
For a native alternative, the black chokeberry, Aronia melanocarpa, also produces attractive fall foliage and black berries.
Considered hardy down to USDA zone 3, you can purchase Viking Aronia Melanocarpa Plant from Burpee.
Grape Hyacinth
Prized for its clusters of small indigo flowers, grape hyacinth (Muscari) is a much-loved spring-flowering bulb that provides a carpet of intense blue color.
Growing to less than 9 inches tall, grape hyacinth might be small, but are highly effective when planted in large drifts or rivers. Nevertheless, these spring bulbs reproduce via offsets and naturalize rapidly, which means that they can be difficult to control.
Muscari tend to produce green foliage in the fall, which stands over winter before they flower again in the spring.
This means that if you need to dig them up to eradicate or control, their green foliage acts as a helpful marker of where the bulbs are situated and they can more easily be dug up when the soil is softer and more workable.
Glory of the Snow (Scilla luciliae, or Chionodoxa Luciliae as it was previously classified) is a less aggressive blue-flowering spring bulb which is suitable for growing in US hardiness zones 4-9. You can purchase Chionodoxa Luciliae (glory of the snow) from Dutch grown.
Porcelain Berry
The porcelain-berry (Ampelopsis brevipedunculata) is another example of an invasive plant that is easier to remove in winter. A vigorous, woody vine, the porcelain-berry outcompetes and engulfs other plants, including native species.
Often removed in winter, when, due to the lack of leaves, the stems are easier to identify, its control measures consist of removing the plant in its entirety, including the roots, where possible.
For the safe disposal of invasive plants, such as the porcelain-berry, Karen advises that, ‘trimmings should be cut into small sections and bagged so that the heat captured in the bag cooks and suffocates the plant parts, ensuring their complete death.
'If you prefer not to use plastics, place your pile of twigs in an area that you check often and is ideally on concrete or asphalt, so the plant parts cannot root into soil and re-establish.’
Karen adds, 'Invasive plant removal can be daunting and overwhelming, especially when trying to manage watering, weeding, pests, and so many other garden tasks – never mind getting to sit back and appreciate your beautiful spaces once in a while! By going into the growing season with already a few invasive plants tackled, you’ll make invasive, weed, and general garden maintenance easier throughout the spring and summer.'
Instead, why not grow crimson glory vine (Vitis coignetiae) with its stunning orange and crimson fall foliage? You can purchase Crimson glory vine seeds on Amazon.
In general, invasive plants are those that have been introduced from abroad and have little to stop their colonization in the way of predators or diseases.
Often outperforming other local and domestic species and endangering local ecosystems, now might be the time to support the vital concept of native planting.
