Choose Native Plants For Vining Green Walls

By Ethan Raysor

Driving through the Brandywine Valley, the Delaware Coast, and the historic farmlands of Delaware, beautiful homes are commonly covered in Hedera helix, or English ivy. This vine became an American ideal for green walls and architectural standards in the early 1900s. Spot its spreading vines inside and outside public buildings, slowly destroying iconic architecture one aerial root at a time. While this plant can be wonderful in indoor settings and controlled outdoor settings, any gardener should beware of this expert escape artist. Though its aesthetic appeal is charming, this invasive plant destroys our forest canopies and ultimately invades any available space. In fact, since the passing and implementation of Senate Bill 22 (commonly known as the Invasive Plant List) the sale of English ivy is now considered illegal in the state of Delaware after July 1, 2022.

English ivy evades its confines when unattended for longer than six months at a time and tracking its spread can be nearly impossible. Its uncontrollable reach can go far from your property lines — creeping into your neighbor’s home or local forests. Here, at Mt. Cuba Center, our horticulturists work to remove any English ivy swiftly.

When English ivy roots itself on structures, it causes harm to the iconic, red brick structures present in Delaware. It secretes a glue-like substance that is stronger and stickier than some human-made substances, like brick mortar. Despite the detrimental effects of English ivy, not all green walls are quite so troublesome. Green walls help absorb sunlight, insulate façades, and reduce energy consumption within homes.

Choosing the right type of “green” material is imperative — especially for those that have historic red brick structures. Alternatives to English ivy, such as native climbing vines like Virginia-creeper (Parthenocissus quinquefolia), secrete milder glue-like substances that are more like suction cups. As an added touch, Virginia-creeper has outstanding red color in fall, satisfying aesthetic valuestoo. Home gardeners will be pleasantly surprised to find that Virginia-creeper is easy to manipulate if it starts to grow in the wrong direction, or even if you want to remove it.

Studies show that common hops (Humulus lupulus) and riparian grape (Vitis riparia), two other native vine species, are also great alternatives to English ivy. Research has found that while grape vines cover a larger area, Virginia-creeper had the lowest number of weeds and invasive species beneath its trellis canopy (due to its dense foliage near the root crown).

Recently, I chose Virginia-creeper as my vine of choice for my home in Historic New Castle. I find that Virginia-creeper is easy to manage (in both removal and surface training) because of the low impact suction; however, it is imperative to plan the placement on the intended surface because it does not prefer trellis training and it does not have a twining habit.

Whether you choose Virginia-creeper or not, there are many native alternatives to the infamous English ivy facades that perpetuate invasive species throughout Delaware’s natural areas.

Here’s a list of native vines with ecological value and aesthetic charm:

• Humulus lupulus (common hops)
• Vitis riparia (riparian grape)
• Wisteria frutescens (American wisteria)
• Clematis viorna (northern leatherflower)
• Lonicera sempervirens (trumpet honeysuckle)
• Gelsemium sempervirens (evening trumpet flower)
• Isotrema macrophyllum (Dutchman’s-pipe)
• Bignonia capreolata (cross vine)
• Clematis virginiana (virgin’s-bower)
• Mikania scandens (climbing hempweed)

No matter what plant you choose to grow on your wall, be aware of the impacts. While the aesthetic of yesterday still prevails in the historic architecture of Delaware, it may be worth taking an ecologically friendly approach to historic preservation by choosing a plant species that is well-suited for the environment and for green infrastructure.