Charleston enjoys an exceptionally long garden season, with at least one plant thriving year-round. Gardeners from colder climates are often surprised by this extended period of growth, as it requires continual trimming and fertilizing throughout the year.
However, the subtropical climate also introduces challenges, particularly the spread of non-native invasive plants. These species have established themselves across the landscape, often proving difficult to control. The most notorious example is the kudzu vine, which blankets and smothers trees, buildings, and anything in its path, earning the nickname “the vine that ate the South.”
While kudzu is a dramatic case, often found on roadsides rather than in gardens, other invasive plants also pose significant problems for home gardeners and should be carefully managed or removed.
Wisteria
Wisteria becomes an Instagram showstopper every April, when its strikingly beautiful clusters of lilac-purple flowers burst forth from fences and trellises in many Charleston gardens. Typically these abundantly blooming ornamentals are not the native American variety (Wisteria frutescens) however, but rather the Chinese (W. sinensis) and Japanese (W. floribunda) varieties, and their intoxicating floral scent just reeks of Springtime in Charleston.
These non-native, invasive species grow incredibly fast, and by summer they are curling themselves around anything and everything – its woody vines will pull down fences, smother shrubs, collapse entire trees, even latch onto and damage your home. I have seen Wisteria pull the wood siding off a house and smother a live oak tree nearly to death in my own yard.
This aggressively invasive plant has proven to be especially problematic in the Lowcountry of South Carolina, where its unchecked perennial growth can blanket entire habitats in a thick canopy. Existing plants invaded by Wisteria are often smothered in the process, overwhelming many native plant and animal species.
Controlling Wisteria
May the odds be ever in your favor.
The base of these vines can be huge and in the worst cases have completely inundated tall trees. Mature growth can require a chainsaw to cut through.
To save a tree that Wisteria has latched onto, one must manually pull the vines out – I recommend starting by killing the vine first since it becomes more brittle once dried out.
Completely cut through the base of the vine with shears or a saw, and (optionally) immediately paint the stub with the strongest systemic herbicide you are comfortable with.
If you are adverse to using such herbicides just know that the vine will absolutely grow back, stronger than ever – but with years of persistence you may eventually succeed in starving the root system.
Best of luck, but invasive Wisteria must be eliminated.
Alternatives to Wisteria
There is a species of Wisteria native to the wetlands of the southeast United States – American Wisteria (Wisteria frutescens) – that has a similar appearance to its cousins but is not quite as aggressive. This Wisteria tends to form shrubs or even small trees, although it can still be a fast climbing vine – just not nearly to the extent of sinensis or floribunda. Its flower bunches are smaller than those of its Asian cousins, and blooms later in summer rather than spring, showing its lovely flowers in June and July.
Other native blooming vines to consider:
- Carolina Jessamine (Gelsemium sempervirens)
- Coral Honeysuckle (Lonicera sempervirens)
- Cross-Vine (Bignonia capreolata)
- American Wisteria (Wisteria frutescens)
- Confederate Jasmine (Trachelospermum jasminoides)
(very common but not native)
Bradford Pear Tree
The Bradford Pear Tree has long been a favorite of landscapers, home builders, and urban arborists since its cultivation in the 1960s by scientists at the US Department of Agriculture.
Marveled as an ideal ornamental tree, the Bradford cultivar matures into a handsome lollipop appearance of medium height, perfect for street trees. With a flush of lovely white blooms in early spring and vibrantly colored leaves in the autumn, the easy-to-grow Bradford Pear spread like wildfire in neighborhoods and along sidewalks across the United States.
After three decades of success, the love affair with the Bradford Pear by the 1990s began to sour into an ecological catastrophe. This non-native cultivar was intended to be sterile so as to be controllable, however the grafting process produced viable seeds and also cross-pollination with other invasive varieties Pyrus calleryana in the wild.
The resulting thickets of thorny, rapidly growing, smelly hybrids have displaced countless native plants and must be mowed down every year.
A further disappointment came for those tasked with caring for these trees – rather than flourishing for decades like similar ornamental trees, they have proven to exhibit a remarkably weak branch structure. During even mild storms the branches of the Bradford Pear can succumb to severe damage from splitting.
Featured in strip malls and parking lots across the United States, they often fail after only 15 to 20 years, much less than their native counterparts.
They fare no better in the yards of homes in Charleston. As such, the Bradford Pear has been deemed the kudzu of trees.
Controlling the Bradford Pear Tree
There is only one solution, and you will have the full support of the S.C. Forestry Commission in doing so: cut them down, every last one.
Clemson University offers a Bradford Pear Bounty in which you can cut down the invasive specimens in exchange for up to five native young trees.
Update 2021: Beginning in 2024, the sale of Bradford Pear Trees will be illegal in the State of South Carolina.
Alternatives to Bradford Pear Tree
I love white flowers on spring blooming trees, and there are plenty of alternatives to Bradford Pear – many that are also native to South Carolina:
Other native blooming vines to consider:
- Flowering Dogwood (Lonicera sempervirens)
- Eastern Redbud (Cercis canadensis)
- Red Maple (Acer rubrum)
- Hawthorn (Crataegus spp.)
- American Fringe Tree (Chionanthus virginicus)
English Ivy
Yes, the handsome ivy leaves found everywhere from bouquets to ground covers is in fact an invasive non-native that will crawl onto anything. Still widely available in garden shops, English Ivy (Hedera helix) will not only take over that garden bed, its vines will climb trees and structures and choke other plants of sunlight, eventually destroying them.
The woody vines embed themselves into tree trunks and are very difficult to remove completely, often leaving scars in the tree bark. The vine is equally happy to grow into the mortar of brickwork, and absolutely causes damage to your home in the process.
Adding insult to injury, English Ivy is known to harbor bacterial leaf scorch (Xylella fastidiosa), a plant pathogen which afflicts a number of our precious native trees including oaks, maples, and elms.
Controlling English Ivy
Pull it out. Uproot the vine when the soil is moist, and be sure to get all of it – this may require multiple visits. Eliminating English Ivy from trees is more difficult; you can tear the vines from the tree bark, but only to the height you can access – anything above that is just going to stay there until it eventually loosens, often hanging loose for years until someone with Tarzan skills shows up to finish the job.
If the infestation is extensive, bring out the big guns – cut what you can and paint the remaining vegetative portions with a systemic herbicide (like concentrated glyphosate – wear protective equipment).
Native Alternatives to English Ivy
- Virginia Creeper (Parthenocissus quinquefolia)
- Wild Ginger (Asarum canadense)
- Allegheny Spurge (Pachysandra procumbens)
- Galax (Galax aphylla)
- Green and Gold (Chrysogonum virginianum)
Excellent Resources
Invasive Plants Booklet from Clemson Cooperative Extension
Native Plant Alternatives from South Carolina Native Plant Society