Unlike some other nasty plants that we feature, this invasive is not a newcomer to town.
I creep and crawl, just like a vine,
Taking ten years to mature, just like fine wine,
My shape-shifting roots secrete natural glue,
Making my spread hard to undo!
(Photo credit: D. Hanna)
English and Irish Ivy (Hedera helix and Hedera hibernica) were introduced to North America, from Europe, through the horticulture trade. Their rapid growth and low-maintenance characteristics aided their use in landscaping. Unfortunately, the fast-growing nature of Ivy would soon land it on invasive species lists in many regions of the world.
English and Irish Ivy have two growth stages: juvenile and mature. In the juvenile stage, the plants have creeping or climbing stems up to 30 m in length. After ten years, the plants reach maturation and develop a thick, woody stem that forms from the ground, eventually becoming a shrub. The woody stems can be 10 cm in diameter—that is about the size of a bagel! The leaves are green and leathery to the touch, and English Ivy has erect hairs on the undersides of leaves while Irish Ivy has flat hairs. When mature, Ivy produces fruit and small, greenish-yellow flowers in umbrella-like clusters.
(Photo credit: J. Ross)
So, what makes Ivy so bad? Ivy infestations form dense monocultures known as “Ivy deserts”. Once spread into parks and natural areas, these ivies suffocate the native plants and trees that make up different levels of the forest. This can lead to unstable hillsides, erosion that pollutes streams, and high fire risk from the “ladders” of ivy vines that climb up the trees. To add, Ivy does not soak up the rain as well as other native plants do, which creates more stormwater runoff. Moreover, the leaves and fruits are toxic to humans, and handling them might cause skin irritations.
Ivy can grow in a range of variable conditions in terms of light, moisture, and pH. However, English and Irish Ivy tend to prefer sunny habitats with moist soils. These species can be found in disturbed areas, fields, parks, forests, coastal areas, and on steep slopes and cliffs. Their climbing vines can be spotted wrapped around trees, walls, houses, fences, posts, and hedges.
While control proves laborious, it is possible (and fairly straightforward)! The best method is to pull them out by hand when the soil is moist. Ensure that as much as possible of the root system is removed, as well as all plant fragments. Any stem or root fragment that touches the soil can sprout into a new plant. To hand-pull, grasp the vine and pull in the direction of growth. If the Ivy vine has climbed up a tree or other structure, first remove leaves and smaller vines to expose the larger vines attached to the structure. Cut the larger vines at shoulder and ankle height using pruning shears, saws, or a hand-axe to stop water and nutrient supply to the plant. If the vines are not embedded into the structure, pull them away with a flat pry bar or a long screwdriver. Ensure that all Ivy has been removed 1-2 m away from the base of the structure. Any Ivy left on the structure above shoulder height will eventually fall away. Ivy is vigorous and grows fast so you’ll need to return to the same area and pull vines several times a year. Just remember to wear gloves to prevent skin irritations!
While Ivy is well established in Squamish, SSISC works to prevent infestations from establishing in both Whistler and Pemberton. If you spot either English or Irish Ivy north of Squamish, please report it here.
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