Clip English Ivy Berries in March
Get your clippers out! Cut the bloominʼ English Ivy berries. Mature English ivy will be producing the purple-black berries full of seeds. These berries are eaten by non-native starlings, like English house sparrows, and a couple of ivy-toxin-tolerant indigenous birds. Seeds in the digested berries are then dropped by the birds everywhere, including the areas of Forest Park and our neighborhood where the habitat still may be uninfected with the ivy plague.
As long as there are sources of seed growing unchecked, the work to restore natural areas and native habitat, and to protect wildlife is much, much harder. The No Ivy Leagueʼs first choice would be to have all English Ivy removed from yards, slopes, trees, walls, and gardens, then replaced by either native plants or non-invasive ornamentals. The League knows not everyone is yet ready to do this, even though English Ivy is on the City of Portlandʼs prohibited plant list for new landscaping projects. But, League is asking everyone to keep areas covered with Ivy trimmed and to cut mature Ivy on trees so that the seed source for new infestation is stopped. For more information, log onto www.noivyleague.org
Replacement Planting for English Ivy
(Editor’s Note: Numerous articles have appeared in previous Ridge Runner issues about English Ivy, a prolific non-native plant that is listed as a noxious weed and quarantined by the Oregon Department of Agriculture. Unlike previous articles, this one recommends good vegetation to plant in places where English ivy has been removed.)
English Ivy (Hedera helix) is an aggressive invader that out-competes native species for light, space, water and nutrients, thus establishing an “ivy desert”. It disrupts natural succession and regeneration of natural areas, makes trees susceptible to toppling and blow-down due to the weight of the climbing vines, and leads to collapse of canopy. Its shallow root system increases erosion, makes slope failure more likely, and can also harbor undesirable vermin.
English ivy was first introduced as an ornamental during colonial times. It is presently used widely in landscaping. Starlings, English house sparrows, and robins disperse the seeds by eating the berries.
For successful control, the roots of English Ivy must be removed. This is usually done by manually pulling them out by hand, with occasional digging necessary. Treatment with appropriate herbicides may also be done when product directions are scrupulously followed. All control methods require follow-up and periodic maintenance.
Once you have cleared the ivy from your property it is important to replant with natives so ivy and other invasive plants will not re-colonize the area. There are many places you can buy native plants at a reasonable price. In addition to the April 7-8 sale at the Skyline Grange, Tualatin Hills Nature Park will have a native plant sale in April, and both the Rock Creek Watershed Partners and Portland Audubon will offer natives plants in May.
Here is a short list of some alternative plants for English ivy. Make sure to buy a plant that has the correct scientific name, not just the common name.
Native Alternatives: Preferred Habitat:
Northwest cinquefoil (Potentilla gracilis) Dry sunny sites; clay okay
Woolly sunflower (Eriophyllum lanatum) Dry sunny sites
Woodland strawberry (Fragaria vesca) Partial shade, prefers rich soil
Twinflower (Linnaea borealis) Shade, soil rich in organics
Bunchberry (Cornus canadensis) Partial shade, soil rich in organics
Wild ginger (Asarum caudatum) Shade, soil rich in organics
False lily-of-the-valley (Maianthemum dilatatum) Shade, moist soils
Piggy-back plant (Tolmiea menziesii) Part shade to shade
Fringecup (Tellima grandiflora) Partial to full shade
Pacific waterleaf (Hydrophyllum tenuipes) Partial to full shade, moist soil
Large-leaved avens (Geum macrophyllum) Sun to partial shade, okay in poor soil
Inside-out flower (Vancouveria hexandra) Partial to full shade, organic soil
Stream violet (Viola glabella) Partial to full shade, organic soil
Sword fern (Polystichum munitum) Partial to full shade
Kinnikinnick (Arctostaphylos uva-ursi) Dry sunny sites, rocky or gravelly
Creeping Oregon-grape (Mahonia repens) Dry sunny sites
Dull Oregon-grape (Mahonia nervosa) Sun to partial shade, acidic soils
Salal (Gaultheria shallon) Sun to shade, moist to dry, acidic soils
For an extended list of native plant alternatives and nurseries go to www.plantnative.org. For more information on English Ivy, log onto Portland’s No Ivy League website at www.noivyleague.com; the Alien Plant Working Group’s website at http://www.nps.gov/plants/alien/fact/hehe1.htm; and the Ivy OUT website at http://www.ivyout.org.
Information for this article was submitted by The Rock Creek Watershed Partners. RCWP is involved in restoration projects that focus on removing invasive species from our local parks and wetlands and replacing them with native plants. For information about their ongoing projects, visit their website at www.rcwp.org, or for information or comments contact them at info [at] rcwp [dot] org or (503) 629-6305 x 2953.