Return to the Landscape Design Forum | Post a Follow-Up

 o
question re the 'ivy question.'...

Posted by woodyoak 5 (My Page) on
Sat, Jun 30, 12 at 15:10

I thought I'd move this comment out of the other post so the discussion can get back to the rest of the OP's issues.

I confess that my bias is not in favor of English ivy outdoors - we battle it coming across/through/underneath the fence between us and the elderly neighbours to the south. Starting two years ago, mature leaves - and flower heads - started appearing at the top of the 6' fence. DH has been reaching across the fence to cut off the flowers we can see. A few weeks ago I spoke to the owners' son-in-law that is temporarily living there and doing a lot of the garden work for them. I explaned why the ivy was 'looking funny' and asked that he cut it back to get rid of all the mature bits. He seemed open to that idea, so we'll see...

Our experiences with it, plus the vigorous views for and against expressed here has made me curious about - is it a problem with gardens in England? How do they manage it? Are there pests or other conditions that keep it more manageable there? I would have thought the conditions in many areas of the UK would be quite similar to the PNW so is it as rampant a grower in the UK as it is in the PNW? It's pretty rampant here but I think our more frequent deep cold spells in winter with not too much protective snow cover can knock it back quite a bit, which probably prevents it from becoming a truly major problem. Ink - you're originally from the UK, right? Can you tell me what the experience with ivy is like there? Anyone else have UK experience with it...?


Follow-Up Postings:

 o
RE: question re the 'ivy question.'...

Don't want to get into this myself, but saw campanula (from Cambridge UK) with a current post in Perennials... asked her to weigh in.


 o
RE: question re the 'ivy question.'...

I did google it and it seemed that most of the problems were related to safely removing it from buildings and fences. There were multiple mentions of it being good for wildlife.


 o
RE: question re the 'ivy question.'...

Buildings in England are made from brick or stone, modern ones with a concrete inner. Older buildings have lime mortar. These porous materials are ideal hosts for ivy to climb on and being that this is the structure of a house ivy can be a problem. In North America/Canada timber is the structure and brick/stone the facade so although ivy can pull down a brick veneer, the house itself doesn't collapse.

Ivy on trees is not acceptable both on aesthetic grounds and for the health of the tree. Other than that I don't recall it being a problem, although I have never known anyone plant ivy.


 o
RE: question re the 'ivy question.'...

I have to put up my hand to having recently planted ivy. Not just one, either....around 60 of them!

But this isn't English ivy. It's Himalayan Ivy. Hedera Nepalensis. Very slow growing and hard to keep alive in the freezing winters at high altitude here. Nature does a good job of keeping it in check.

I need to hide the 3 metre high, 600 metre chain-link perimeter fence that encloses our 5 acre project...


Regards to all,
Shax.


 o
RE: question re the 'ivy question.'...

  • Posted by bahia SF Bay Area (My Page) on
    Sun, Jul 1, 12 at 2:26

Woody, I did post a similar question to UK gardeners on the plant forum Growing on the Edge, and most said it is a valuable native which provides food/berries for native birds in winter, but it is just as likely to become a pest/maintenance headache over there as here in the USA/Canada, and has no significant insect pests which keep it in check there. On the other hand, it is a native plant in the UK, so presumably would be considered more valuable as such. Personally I'd still recommend avoiding it for the same reasons that apply this side of the Atlantic.


 o
RE: question re the 'ivy question.'...

  • Posted by bahia SF Bay Area (My Page) on
    Sun, Jul 1, 12 at 2:28

Woody, I did post a similar question to UK gardeners on the plant forum Growing on the Edge, and most said it is a valuable native which provides food/berries for native birds in winter, but it is just as likely to become a pest/maintenance headache over there as here in the USA/Canada, and has no significant insect pests which keep it in check there. On the other hand, it is a native plant in the UK, so presumably would be considered more valuable as such. Personally I'd still recommend avoiding it for the same reasons that apply this side of the Atlantic.


 o
RE: question re the 'ivy question.'...

what are the most common problems I would encounter with that plant?


 o
RE: question re the 'ivy question.'...

  • Posted by botann z8 SEof Seattle (My Page) on
    Sun, Jul 1, 12 at 14:10

Depends where you live in the states would give us an idea of the problems you would encounter.
Mike


 o
RE: question re the 'ivy question.'...

  • Posted by bahia SF Bay Area (My Page) on
    Mon, Jul 2, 12 at 4:59

When it is planted where it can climb trees or fences/walls it will eventjally form adult foliage that flowers and fruits. In many parts of the country it has been declared an invasive weed. Anywhere it isn't maintained, it can invade into neighbor's gardens, seedlings come up everywhere from bird spread seed in gardens as well as untouched natural areas becoming problematic. Plus, it can harbor rats and encourage build-up of large snail populations which can encourage raccoons and their populations to increase.


 o
RE: question re the 'ivy question.'...

It became apparent in one of the earlier discussions about ivy is that people tend to lump the various ivieS together as though they are the same. Algerian ivy is thrown into mix and comments which apply to it, but not to English ivy, are made as though there is no difference. I'm not familiar with Algerian ivy first-hand, but I've seen photos that show ivy heaped up on itself, as in the picture below, which I know English does not do. It's almost as if the plant creates a miniature "hut" of sorts. People seem to maintain these mounds as if they are shrubs.

When claims are made about a plant, I think people need to take a harder look at the science that is behind the claim. Often, it turns out that it's faulty or non-existent. (The same is true in health and medicine and many other sciences.) People pass claims around for decades before they learn that they're not based on good studies. In the case of English ivy, when I came across a website denigrating it, but that featured a photo of Kudzu "swallowing" a car as an example of how evil ivy really is, it was clear that there's a lot of politicizing about the plant! At the least, a discussion of it should not confuse it with any other plant.


 o
RE: question re the 'ivy question.'...

OK, you've piqued my curiosity as to what ivy we're talking about. It turns out it's not that simple, as the two common ivies in the pacific northwest (PNW) are not easy to tell apart. In the past they were considered by some taxonomists to be different varieties of the same species, Hedera helix.

The two ivies under scrutiny in the PNW are English ivy (Hedera helix) and Atlantic ivy (also called Irish ivy) (Hedera hibernica). Algerian ivy (Hedera algeriensis) is troublesome in southern California.

English ivy (H. helix) ranges through much of Europe, from Norway to northern Africa and east to the Ukraine, while Atlantic ivy's natural range is limited to the coastal areas of w Europe (although it is planted throughout Europe).

The shape of leaf hairs is one of the morphological features used in distinguishing English, Atlantic and Algerian ivy. In the lab, genetic analysis (DNA markers) is used to distinguish them. In the study in the link below, out of 119 samples of invading ivy, 83% were Atlantic ivy; the rest were the English ivy cultivars 'Baltica', 'Pittsburgh' and 'Star', or were unidentified cultivars of English ivy or hybrids.

Both English and Atlantic ivy are sold as "English ivy" is the US. To be more technically correct when talking about PNW invasive ivies, one could refer to them as "the English ivy complex". Or perhaps, "English ivy and its kin". Oh heck, I'll just say "English ivy" most of the time.

-m

Here is a link that might be useful: Invasive Hedera taxa


 o
RE: question re the 'ivy question.'...

  • Posted by bahia SF Bay Area (My Page) on
    Tue, Jul 3, 12 at 2:45

We've had this discussion ad nauseum before, both English Ivy and Algerian Ivy are equally invasive here in northern California when allowed (or ignored), and flower and set seed, which is highly attractive to birds which then spread ivy over wide areas where it can be a nuisance to other gardeners as well as invade wild landscapes and become problematic. Certain people seem so invested in the alleged valuable characteristics of English ivy in particular that they fail to recognize how bird spread invasives are particularly troublesome to prevent their spread. Both English and Algerian ivies are equally adept as invasives here on the west coast wherever both are winter hardy. English ivy has the same capacity to be bird spread in the UK and become invasive in woodland habitats, and also has the same propensity to annoy the adjoining neighbors of ivy landscapes when not effectively managed at property lines. I'm sure there is no shortage of info on line that improperly conflates English ivy with other plants, but it is a red herring to then assume English ivy is never problematic as a potential invasive across large parts of the USA. Bird spread seed of plants that readily grow and overtake native habitat can be compared to how flu spreads; it can seem unstoppable and spread across large distances.


 o
RE: question re the 'ivy question.'...

I'm still wondering about how differently it behaves in North America vs. the UK... Bahia - it appears that from what your UK contacts say, that it can be a pest in gardens and elswhere; and Ink, you said you don't remember anyone planting it. I'm an RHS member and I don't remember ever seeing anything in the Garden magazine about it with respect to invasiveness or difficulty controlling it etc. It occurs to me that a key difference might be something to do with trees - my understanding is that there are not a lot of native softwood/conifer trees in the UK; that a lot of the conifers are ones introduced from North America or elsewhere. I wonder if the deciduous hardwood trees that would have been the dominant native trees in most areas, are better able to cope with ivy because they have stronger wood - and perhaps their roots compete more strongly with the ivy's roots too...? Given the dominance of evergreen softwood forests in a lot of the areas where ivy is particularly a problem in North America, perhaps the weaker softwood makes the trees more vulnerable...? And perhaps there is something significant in the balance of evergreen/deciduous trees that English ivy evolved with...? The two things that come to mind quickly are the physical differences in the structure of deciduous hardwoods vs. softwood conifers, and the possible differences in effect of an evergreen vine competing for light on an evergreen tree vs. on a deciduous one.


 o
RE: question re the 'ivy question.'...

Interesting Woodyoak. Particularly given the amount of time I spend battling our two native, potentially very large growing vines, Virginia creeper and poison ivy.

Given that the original tree canopy here would have been about 100 ft up in the air, anything that is going to get light under those circumstances has to be able to get big itself. So the only thing really meant by saying these vines can grow over 100 ft is that they can get to the top of a mature tree. Not necessarily that they will smother that tree. It sounds like English ivy behaves in England much more like Virginia creeper does here, than ivy in other parts of the US.

BTW, ivy of any sort gets mashed periodically by winter here. That is probably an important variable here. I know from discussions on other forums that the eastern US is much colder, much further south, than West Coast people assume.


 o
RE: question re the 'ivy question.'...

Woody, I think your initial question that frames the thread is a good one and one that I've wondered about myself. How does English ivy behave in England and/or other places where it thrives? And how do people manage it... or do people only throw their hands up in despair over it?

"...it is a red herring to then assume English ivy is never problematic as a potential invasive..."

Sometimes on the forum there seems to be a tendency for one person to talk oranges and another person to talk apples and for one of them to lob the charge that the other "only hears what they want to hear." As one of the predominant defenders of English ivy in the discussions that have taken place about it over the past year, I have never made the claim that it is "never problematic" in all places and under all conditions. I have never heard anyone else make such claims either. (Of course I could be proved wrong if someone digs up a quote that says otherwise.) My claim is that it CAN be managed... quite well, far better--satisfactorily even--in some places than many people seem to know. If people would be reasonable, fair--and accurate--when they discuss it, it might be an intelligent discussion. But presuming that Hedera helix can only be bad in all places if it is bad in any place... or talking about other ivies as if they were all the same, is an emotional reaction that cannot result in an intelligent discussion of the plant. That English ivy can "seem unstoppable" might be little more than knowing effective ways to stop it and taking the steps necessary to do it. In an urban area, if bird-spread ivy were a big problem, it might also mean undertaking an educational campaign that informed people of the dangers of allowing ivy to climb unhindered (much as a campaign against pools of standing water helps in combating the proliferation of mosquitoes.) I'm not even saying a person would need to do this on their own. Usually, when problems reach the level of being "big," grass roots organizations form with an intent to do something about them.

[mad_gallica, I've had great success with the complete eradication of poison ivy in spite of being surrounded by un-managed hoards of it. It can be done in a single year with a little persistence. I've also learned that even if one comes in contact with it, the nasty effects can be entirely avoided if one showers shortly thereafter (the "window" might be as much as an hour or even a little more) and carefully handles any exposed clothing until it gets to the washer.]


 o
RE: question re the 'ivy question.'...

The issue with English ivy or "the English ivy complex" in those areas where it is particularly problematic - ie. WA/OR or the PNW and probably CA as well - is that it is impossible to monitor its growth and/or maintenance on private property. There is no "ivy police" to go around and make sure everyone is trimming their ivy and eliminating any potential for it to mound or climb, develop adult foliage and eventually flower and fruit. Not everyone is responsible about maintaining their property and since English ivy has long ago escaped cultivation and now populates greenbelts and vast tracts of woodlands, even if they were, the problem would be only fractionally reduced. So assumptions that it can be managed in these areas and under these situations are preposterous.

FWIW, there are numerous grass roots organizations dedicated to ivy removal in the PNW - ie. the 'No Ivy League' - and without their dedicated volunteer efforts, the ivy issue in parks and public lands would be much worse. But it is simplistic in the extreme to make a statement that just proper maintenance would eliminate, reduce or even potentially keep the problem in check.

The answer is pretty darn simple. In those areas where English ivy or any other ivy species is problematic, it should be (and most often IS) classified as a noxious weed/invasive species and its propagation and sale prohibited. We may never succeed in removing ivy completely from our landscapes and our public lands but at least we can be assured that we are not unnecessarily attempting to perpetuate the problem by selling the plant or encouraging anyone to plant it.


 o
RE: question re the 'ivy question.'...

Yard - one big advantage I can see to 'overstating' the negatives is the issue of inexperienced gardeners. Given that the various ivies are not easy to tell apart, especially for 'newbie' gardeners, it makes a fair bit of sense to say BE CAREFUL/DON'T PLANT THIS! It doesn't take much reading on any GW forum - or any other garden forum - to realize there are hordes of gardeners - both new and with varying degrees of experience - who are highly unlikely to do what is necessary to control thugs even if they recognize that what they've planted is a real or potential thug! I grow both Chinese and Japanese wisterias and love them. BUT I always say they are potential monsters and should not be planted by anyone who is not going to do what is necessary to control them; and that I'd never grow them as vines - only as 'trees' to make control easier; and that I'd not plant them if I was in a warmer zone. So, while I find the 'never plant a wisteria' recommendations one often sees to be a bit extreme, I fully understand why that recommendation is made and agree with it as it applies to most people in a great number of places. It's sort of the same approach that one should use in one's personal financial planning :-) It's better to over estimate your expenses (the negatives/problems) and under estimate your income (the positives/benefits) than the other way around! That philosophy applies to ives, wisterias, and many other plants too.


 o
RE: question re the 'ivy question.'...

gg48 and I were posting at the same time....


 o
RE: question re the 'ivy question.'...

BTW Yard - I just realized you misunderstood the question I was asking... I'm not asking why/how can it be controlled in England so people there don't 'throw up their hands', but rather I am asking what is the difference between conditions there and here in North America that makes English ivy a problem in so many places here?


 o
RE: question re the 'ivy question.'...

Woody, I can't answer your question specifically but must conclude that, as pertaining to any invasive species, location is everything! What conditions exist in the UK that limit its rapaciousness there that do not exist in the PNW I am not sure but it is not necessarily limted to ivy. Spurge laurel, Daphne laureola, also a moderately well-behaved UK native, is a bird-spread noxious weed in the PNW as well. Why is Japanese barberry/heavenly bamboo/burning bush each an invasive plant on the east coast but well-behaved garden ornamentals on the west? I am sure it has a great deal to do with temperature and weather patterns, rainfall/moisture levels and when precisely the seeds are ripe for germination.

And maybe even the amount of wildlife - mainly birds - available and willing to spread the seed. Interestingly, other mostly bird-spread plants here that are also borderline noxious weeds are English laurel (Prunus laurocerasus) and English holly (Ilex aquifolium). And yes, I know neither is specifically native to the UK despite their common names :-)


 o
RE: question re the 'ivy question.'...

gg48 - one of my main characteristics in boundless curiosity :-) I wonder if anyone has tried to sort out which combinations of the plants' physiology, climate, interaction with insects and other wildlife, etc. are the main culprits for various plants' agressive spreading? Sounds like approprite projects for ecology students' graduate work... :-) There is probably a thesis or two out there somewhere - something to add to my list of things to Google when I have nothing better to do...! I had hoped someone might have been aware of research like that that might have been done re ivy.


 o
RE: question re the 'ivy question.'...

This is all very unscientific speculation on my part but it seems to me that a lot of indigenous plants survive because they have adapted to harsh conditions. If they are transplanted into the equivalent of a horticultural paradise they often lose their way (pun intended). Your friend Gertrude was fond of Giant Hogweed, a statuesque plant if ever there was one that she and William Robinson planted in their gardens that now haunts the Surrey countryside in all its poisonous glory. I have seen Buddleia growing through the windows and in the gutters of an abandoned building in England yet trying to have it survive here is, well, trying.


 o
RE: question re the 'ivy question.'...

Ink - true... It's always interesting to read in the Garden and elsewhere about those darned invasive North American plants!


 o
RE: question re the 'ivy question.'...

gardengal - Although ivy is classified as a noxious weed here, I'm surprised that it is still legal to sell it. The link explains why.

Here is a link that might be useful: Poison ivy, unholy holly, and lax weed laws (in Washington state)


 o
RE: question re the 'ivy question.'...

Woodyoak - for reading about invasive plants, there are a few of Sarah Reichard's papers online. She has also published the books "Invasive species in the Pacific Northwest" and "The Conscientious Gardener: Creating a Garden Ethic", neither of which I've read.

Here is a link that might be useful: link to articles & books about invasive plants


 o
RE: question re the 'ivy question.'...

"...one big advantage I can see to 'overstating' the negatives is the issue of inexperienced gardeners."

If a discussion must avoid accuracy for the sake of shaping policy, then its value as an intellectual discussion fizzles. "Inexperience" doesn't mean that a person can't comprehend a simple warning and there's not been any ivy discussion occurred here in the past year that hasn't been rife with an overabundance of warnings.

"BTW Yard - I just realized you misunderstood the question I was asking... I'm not asking why/how can it be controlled in England so people there don't 'throw up their hands', but rather I am asking what is the difference between conditions there and here in North America that makes English ivy a problem in so many places here?"

Does your initial question presuppose that Hedera helix is tame--or much more tame--in England?


 o
RE: question re the 'ivy question.'...

Yard - my initial question presupposed that, since I don't remember reading anything in English sources about dire effects on trees etc., there must be some reason for that in terms of something different there than here (e.g. pests of some sort or other unidentified conditions...) It was probably misleading of me to use the word garden when I was interested in the bigger picture also - although I did also wonder about it in gardens too... (Bahia and Ink's input helped answer that question, as well as a recent post on GW that included comments from an English gardener on controlling ivy in the garden - she does much the same things as I do to control the ivy coming from my neighbours...)

It just occurred to me to check the RHS web site re ivy. Interesting... While this doesn't explain why the ivy would be more damaging in areas of North America, it's interesting to see the English perspective on it:
"Just how harmful is ivy? Here are some facts that will help you decide;

- Ivy growing on trees is often thought to be a serious problem, endangering the health of even very large trees. However, its presence on the trunk is not damaging and where it grows into the crowns this is usually only because the trees are already in decline or are diseased and slowly dying
- If the branch canopy becomes thin and allows sufficient light to enter, the ivy will develop into its arboreal form. Fraxinus (ash), a naturally thin, open-crowned tree may suffer heavy infestation, and for this reason ivy on ash trees is often controlled
- When trees grown for their stem or bark, such as birch and some acers, keep the stems or trunks free from ivy
- On other trees, ivy can be allowed to grow on the trunk, although one problem with very old or damaged trees is that the ivy may hide cavities which, in time, could gradually enlarge and possibly affect stability
- Ivy is not a parasite; the short, root-like growths which form along climbing stems are for support only. Its own root system below ground supplies it with water and nutrients and is unlikely to be strongly competitive with the trees on which it is growing
- Ivy has much wildlife value. As ground cover in woodland, ivy greatly lessens the effect of frost, enabling birds and woodland creatures to forage in leaf litter during bitter spells. Growing on trees, it provides hiding, roosting, hibernating and nesting places for various animals, birds and insects (including butterflies), particularly during the winter months and in areas where there are few other evergreens.
Note: If you are concerned about an old or diseased tree, always seek professional advice from an arboriculturist or tree surgeon."

Their recommendation on how to control it when it is an unwanted groundcover and you don't want to use chemicals:
"Dig up all stems and woody roots. This may be difficult on heavy soils or where vegetation is very dense. Where the site is not needed for planting, an alternative control method is to clear away all top growth before laying weed-control fabric and a 10-15cm (4-6in) deep layer of bark mulch. Leave in place for at least two growing seasons."

I would bet that a big part of the problem here is likely due to the greater presence of evergreen conifers here that are not evolved to live with evergreen vines. I'm not sure about the PNW, but most forest vines here are deciduous, so are likely less stressful on the trees when they climb on an evergreen conifer. And I wonder if the local bird populations have developed a strong preference for this 'exotic' food source... :-) Note that the RHS info only seems to be talking about deciduous trees and makes reference to ivy having value particularly in the absence of evergreen trees. So I think the the difference in the type of trees in forests between here and there is very much likely to be a key factor in how ivy performs in the environment here relative to there.


 o
RE: question re the 'ivy question.'...

"Yard - my initial question presupposed that... " [Hedera helix is tame (or substantially more tame) in England.]

That seems a stretch. It could very well be that ivy grows as rampaciously in England but that they've learned to cope with it and manage it better. Also, since they seem to suffer somewhat less overall from hortiphobia, they might not mind it as much. As a rule, compared to Americans they seem to like a fair amount of smothery green. A typical drive there can seem claustrophobic compared to a typical drive in the US. I know English ivy grows into trees there just like it does in various places in the US. It also grows lush and thick. That ivy is not as vigorous a plant in the UK as it is in parts of the US would need hard evidence before many could accept it as fact. Here's a couple of shots that lean to the contrary.

I would bet that another complication to the ivy issue is the mere fact that it is not native. If it were native, people wouldn't be hoping so much to send it back from whence it came.

Image Hosted by ImageShack.us
B

Image Hosted by ImageShack.us


 o
RE: question re the 'ivy question.'...

I have no idea why I feel compelled to step into this discussion (hornet's nest?) again. But...

Ivy remains in its juvenile form for 10 years or more. It starts bearing seeds after it takes on its adult form. This is the unattractive mounding form with unlobed leaves and it can survive decades or, it's claimed, 100's of years. Perhaps the various cultivars could be genetically engineered to remain perpetually in the juvenile form. These could be propagated asexually for sale. Then if states prohibit the sale of non-adult-form-capable ivy, at least these would not contribute to the explosion of bird-spread ivies. Not sure if this could be done, but it's a thought.

-m


 o
RE: question re the 'ivy question.'...

That would be the greatest solution if an English ivy could be genetically engineered to not be capable of achieving adult stage. But even if it's achieved it will take quite some time of testing before it could be trusted.

Ish, I question if the 10-year claim is accurate. I think it has as much or more to do with conditions and that young ivy, if allowed to climb, could achieve adult stage much faster than in ten years. Also, I never observed English ivy mounding onto itself (as per the photo I submitted July 2.) This seems to be the habit of Algerian ivy.


 o
RE: question re the 'ivy question.'...

I regret starting this thread!


 o
RE: question re the 'ivy question.'...

And here I thought everything that could possibly be said about ivy was said.

I did "enjoy" watching a team of painters - over a summer - removing ivy (and it matters not to me whether it was Boston, English, Algerian...) from a large stucco house. Getting the plant down was one thing, literally hand scraping off the tendrils, etc. was something else again.

The next topic should be Campsis Radicans in every yard - yay or nay.


 o
RE: question re the 'ivy question.'...

Woodyoak, and I'm sorry for getting too far away from your original questions, which are good ones.
-m


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Landscape Design Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here