“Pittsburgh Ivy” is a localized term referring to a particularly resilient and cold-hardy cultivar of English Ivy, scientifically known as Hedera helix ‘Pittsburgh’. This evergreen vine is ubiquitous in the landscape around Pittsburgh because it thrives despite harsh winter conditions. The nickname reflects the plant’s widespread presence in both managed gardens and natural areas. This ivy is both a popular ornamental choice and a significant ecological concern.
Defining Pittsburgh Ivy
Pittsburgh Ivy is a specific cultivar of the common European English Ivy, Hedera helix. Its local prominence is due to its superior hardiness, allowing it to withstand the colder temperatures of the northeastern United States, including USDA hardiness zones 5 and 6. This characteristic distinguishes it from many standard English Ivy varieties. The cultivar is recognized by its dense growth habit and comparatively small, glossy, deep green leaves.
The leaves of H. helix ‘Pittsburgh’ typically have three to five pointed lobes and measure about 3 to 4 centimeters in length. This dense, compact foliage gives the plant a bushy, mounding appearance, especially when used as a ground cover. Its robust nature and reliable evergreen color made it a popular choice for gardeners seeking a durable, low-maintenance option.
Growth Patterns and Cultivation
Hedera helix ‘Pittsburgh’ is highly valued for its versatility, functioning effectively as both a vigorous ground cover and a self-clinging climbing vine. As ground cover, it forms dense, thick carpets. As a climber, it uses aerial rootlets to attach to surfaces, potentially reaching heights of 3 to 10 meters. This adaptability allows it to be used for green walls, fences, or to cover bare earth in challenging areas.
The plant is notably tolerant of various light conditions, growing well in full sun, partial shade, or full shade, making it ideal for areas under trees or on the north side of structures. It is also highly adaptable regarding soil, thriving in neutral to alkaline pH levels and a range of soil types, provided the soil is moist but well-drained. Gardeners intending to keep the ivy contained must perform regular pruning, which helps control its rapid spread and maintains a desirable shape. Pruning is important for climbing ivy, as it can quickly overwhelm structures if left unchecked.
Controlling Its Spread
English Ivy is classified as an invasive plant in Pennsylvania and many other states due to its aggressive growth and negative impact on native ecosystems. As a ground cover, it forms dense monocultures that prevent native plants from establishing, eliminating food sources and habitat for local wildlife. When it climbs trees, the dense foliage blocks sunlight, hindering photosynthesis and making the host tree more susceptible to blow-over during storms due to the added weight.
The most effective control strategy involves thorough mechanical removal, as the plant can re-root from stem fragments.
Removing Climbing Ivy
For ivy climbing a tree, the vines must be severed at both ankle and shoulder height. The section between the cuts should be stripped away carefully to avoid damaging the tree’s bark. The upper vines will die and fall off, while the ground-level portion must be removed.
Ground Cover and Chemical Control
For ground cover, hand-pulling is labor-intensive, or the area can be smothered with several inches of biodegradable mulch for at least two growing seasons. Chemical control involves applying an herbicide to the foliage or directly to the woody stem stumps after cutting. Homeowners should remove the ivy at least six feet from the base of any trees to prevent re-climbing.