Plant of the Week: Ivy, English
The University of Arkansas System Division of Agriculture does not promote, support or recommend plants featured in "Plant of the Week." Please consult your local Extension office for plants suitable for your region.
Plant of the Week
Latin: Hedera helix
Gardeners, like voters, are influenced by their temperament and passion. I consider
myself a solid centrist in this area. I try to recognize the intrinsic value of all
garden plants and not get too consumed by the flaws that all plants possess. But those
to my right in the political array consider me a hopelessly ill-informed bleeding
heart that does not recognize the menace that lurks around the next bend in the garden
English Ivy is often considered one of these menacing plants.
This climbing, evergreen ivy is a member of the aralia family and was introduced during the colonial era into the US. English Ivy is a rampant vine that will creep across the ground until it finds something to climb, and then it’s off like a rocket up the tree trunk or wall.
Ivy takes on two distinct leaf types -- the familiar three or five-lobed leaf of the fast growing vine and the less familiar unlobed leaf with a long petiole. This difference in leaf shape is due to the physiological age of the plant, not its chronological age. As long as ivy is kept on the ground or kept on an upward quest, it will remain in the juvenile stage and its leaves will maintain their familiar lobed appearance. If the plant is kept confined to a groundcover bed this condition will be maintained indefinitely.
Once a plant has climbed something and reached the point where it can grow no further, it will make the magical transformation to adulthood. Of course with adulthood comes sex and before you know it there are babies to feed. The white flowers are round pin-cushion like balls that appear in clusters at the end of the branches that emerge once the ivy attains adulthood. When ripe the seeds are black, and though somewhat dry, still relished by birds.
Ivy climbs, not by twining, but by modified stem roots that form a suction-cup structure known as a "hold fast." These suction cups adhere to about anything from tree bark to bricks and remain in place when the ivy is ripped down. If ivy is allowed to climb on a brick wall and later removed, nothing short of sandblasting will remove these well-cemented hold fasts.
The lament is often heard that ivy is "killing my tree." While this makes intuitive sense, English Ivy is in no way parasitic and does not kill trees -- at least not healthy trees. Ivy that is allowed to climb trees will develop a thick trunk, often the size of a man’s arm, and quickly invade the canopy of the tree. But, as ivy is a shade plant, it usually lurks in the shadow of the canopy a few feet shy of exposure to full sun. All of this ivy mass in the top of the tree can cause weakened trees to topple over in a wind, or struggling trees may produce so little new growth that the ivy shades out the remaining part of the canopy.
The fear of ivy destroying buildings also needs mention. Ivy hold fasts can create a maintenance headache if allowed to form on a wall, but they will not grow into and destroy sound mortar and brick. Wood, though is a different matter and ivy can keep the moisture level high and encourage wood rot. It also can grow under wooden siding and cause problems. One of my previous houses had an ivy bed outside by the chimney where it was allowed to climb. One spring a shoot found its way through the wall and I had a nice houseplant that I didn’t have to water. Being the lazy soul that I am, I assumed that the vine was plugging a hole in the wall, thus keeping out cold drafts. My wife soon pointed out the error in my thinking before the vine expanded enough to any real damage.
English Ivy can be used as a very effective groundcover in even the shadiest gardens, but in my opinion, it should not be allowed to climb. By keeping it from climbing we are in effect neutering it, just as we do with our pets so that we do not have to deal with unwanted offspring. But even if you choose to let it run free as nature intended, be assured it will not greet you at the door one fine morning and strangle you as you walk to the drive to get the paper.
By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Extension News - December 1, 2000
The University of Arkansas Division of Agriculture does not maintain lists of retail outlets where these plants can be purchased. Please check your local nursery or other retail outlets to ask about the availability of these plants for your growing area.