Will Wisteria Vine Kill Live Oaks?

Regional Scope

• The live oak is native to the warmest winter areas of the southeastern coastal plain from Virginia to Florida and eastern Texas. It is grown in U.S. Department of Agriculture plant hardiness zones 8 through 11. Chinese and Japanese wisteria grow best in regions with a cold winter, zones 5 through 9. Issues of competition and harm from wisteria vines and live oak trees are most prevalent and concerning in zones 8 and 9.

Growth Concerns

• The growth pace of a live oak pales in comparison to that of both Japanese and Chinese wisteria vines. While the oak tree slowly grows upward with spreading branches, the voracious stems with clinging tendrils of wisteria clamber over anything in its path toward sunlight. Wisteria vines will fully cloak any plant under 30 feet in height, and the Chinese wisteria can tower up to 80 or 90 feet. While the vines do not strangle or poison the plant they cover, the vines' foliage smothers sunlight to the lower plant, effectively reducing photosynthesis and weakening it.

Effect on Live Oak

• Keep Japanese and Chinese wisteria vines away from and off of the leafy canopies of live oak trees. If the oak tree is young and small, under 30 feet, expect either wisteria to climb it and choke out all sunlight to the oak. After two years of coverage, the live oak sustains loss of foliage,uneven growth on branch tips in sunlight, substantial limb dieback and even death if the tree is simultaneously plagued by drought or other ailment.

Large Tree Insight

• On old, tall or wide-spreading live oak trees, the sheer size of the canopy can provide enough dense shade to potentially limit the establishment or spread of wisteria vines under it. This doesn't prevent wisteria from still clambering up and over the lower canopy branches on the live oak. Rather than killing the tree, dense wisteria foliage can denude and kill the lower branches while the sun-basking upper canopy of a live oak continues to grow unaffected. The best advise is to remove wisteria vines -- especially the taller growing Chinese wisteria -- from all branches on a large live oak to preserve the vitality of the oak, rather than let the wisteria gain any advantage.