Will vermin be attracted to Oregon grape?

Discussion in 'Outdoor Gardening in the Pacific Northwest' started by Cantabrigienne, Dec 18, 2021.

  1. Cantabrigienne

    Cantabrigienne New Member

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    I'm planning new plantings for my strata building building in Vancouver. Our building is on a street lined with tall lindens, so most of the garden is very shady.

    I would love to use mahonia aquifolium to provide privacy for the ground floor units, but am concerned that the berries would attract vermin: We have a mice & rat problem that is only just coming under control with more aggressive trapping. (I'd really love to use vaccinium ovatum but I suspect that's out of the question.) Am I right to be concerned, or would they only attract birds (or nothing at all)?
     
  2. Ron B

    Ron B Paragon of Plants 10 Years

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    Tall Oregon grape is slow growing and often lacks density anyway. In addition it can be prone to rust - if you are trying to do a natives only + no berries combination that is going to be quite limiting. For starters the natives only filter right there really cuts down the possibilities with many landscape situations. Including any site where the soil structure has been significantly altered - the native plants that are most attractive for typical garden settings are not among the assemblage that comes up on soils like what site clearance and development activities often leave behind.
     
    Last edited: Dec 18, 2021
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  3. Margot

    Margot Renowned Contributor 10 Years

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    Nothing eats Vaccinium ovatum berries in my garden and I don't know why because they are delicious. I find it very slow growing though so, even if the soil is optimal, it may take too long to achieve the privacy you're looking for.
     
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  4. Ron B

    Ron B Paragon of Plants 10 Years

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    Vaccinium ovatum shoots up pretty quickly if soil is kept quite moist. Mice go for salal berries so one would think evergreen huckleberry would be on the menu also. And indeed multiple online references mention it being a rodent food source. With the page below having various native plants in a table format where it can be quickly seen which ones have the rodent icon in the last cell of each row:

    final native plant recommended list.xls (oregonstate.edu)
     
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  5. Georgia Strait

    Georgia Strait Generous Contributor

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    Are there any Nandina that anyone would recommend for a compact tidy strata edging — I think I have seen them in those sidewalk entry condos where leaves are imprinted in sidewalk around Yaletown / Roundhouse

    Are there any small size (naturally ) Pieris japonica

    boxwood (buxus)?
     
  6. Ron B

    Ron B Paragon of Plants 10 Years

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    Dwarf cultivars of all three are on the general market. However Nandina is prone to mildew in our region and box often discolors on local soils, is subject to box blight. With the much planted 'Suffruticosa' being about the worst in this respect. And if the role of the new planting is to be screening - with tall Oregon grape being the first kind considered - dwarf shrubs may not be big enough.
     
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  7. Georgia Strait

    Georgia Strait Generous Contributor

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    What about a row of boxwood (buxus) - what do others think?

    some are rounder habit and some are taller etc

    Yes, somewhat growing (EDIT slow) tho so is mahonia

    This is a longer term advantage

    it would be worth checking out prices from reliable nursery
     
    Last edited: Dec 19, 2021
  8. Margot

    Margot Renowned Contributor 10 Years

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    Just for interest's sake, here is one of my Vaccinium ovatum planted in 2012. (You have to look hard to see it.) It has received regular watering ever since and is now 6 - 7 feet tall.

    When I went outside a moment ago, the garden was full of birds but I notice there are still quite a few berries on the bush. There are always rodents around too. Weird, eh?

    Vaccinium ovatum 12-2012.png Vaccinium ovatum 12-2021.JPG Vaccinium ovatum 12-2021 (2).JPG
     
  9. Ron B

    Ron B Paragon of Plants 10 Years

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    The disease is especially severe in the landscape where plants are sheared tightly and/or planted in hedges. In nurseries, boxwood blight is especially severe in situations where there is high humidity or where moisture remains on leaves for long periods of time. This includes plants in propagation greenhouses, those watered too frequently without sufficient time to dry between irrigation events, or are shaded by taller plants or structures nearby the production area. Plants that are tightly spaced in flats, grown pot-to-pot, or other spacing where plant canopies touch each other are also at risk for more severe disease. Due to the history of this disease, its explosive life cycle, and subtle symptoms on tolerant plants, it is expected to be an ever-increasing problem throughout the PNW.

    Boxwood (Buxus spp.)-Box Blight | Pacific Northwest Pest Management Handbooks (pnwhandbooks.org)
     
    Last edited: Dec 19, 2021
  10. Cantabrigienne

    Cantabrigienne New Member

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    TBH, it sounds like I should focus on rearranging the budget for hardscaping and just get some privacy screens installed. We're in limbo in terms of timeframe for planning. The garden was wrecked after our rainscreen project; it was under plywood for a year and the compacted soil is not draining well, which is raising the risk of water ingress. So we have a costly job of removing the soil & installing new turf ahead of us. (We started off asking for a dry river design and no grass, but the cost was double our budget; meanwhile and the quotes I've been getting to maintain a no-grass garden are 1.5x what our current landscaper charges us for our mostly lawn arrangement.) And yet we know that by ~2030 we will need to do a podium job, which will involve ripping out the whole garden to put in new membrane over the whole podium so we're not in a position to use slow growing shrubs.

    The other complication is that we're planting things in less than a foot of soil for most part. It's a minor miracle we don't have any serious problems already - one landscaper I interviewed was telling me his team was removing trees from the roof of a building in Olympic Village and replace them with some variety of amelanchier because their roots would not pose as much of a threat.

    There is quite a lot of Nandina and Physocarpus on the current draft of the landscape plan, with Choisya ternata on the sunnier side of the building. I requested Pieris japonica but the landscape designer nixed as being prone to some problem I cannot recall. The initial costly plan had hedges of Taxus media Hicks for screening the ground floor units, but @$100 per 4ft yew or more, that seemed like an option we couldn't afford. (I have price lists from Specimen Trees & Golden Spruce.) There is Buxus on the plan, but mostly for visual punctuation rather than hedging. One ground floor owner is very vocal in their hatred of rhododendrons ("gross wet petals all over my patio" was their complaint) which is what we had growing around their patios originally so I'm looking for alternatives to that. Can't please everyone tho, so since I have to take the long term interests of the building as my main criteria, might still end up with rhodos.

    Shrubs I have noticed & identified via plant apps while walking around are Aucuba japanica, Pyracantha, Cotoneaster salicifolius, and Elaeagnus pungens 'Maculata' - any thoughts about these?
     
  11. Georgia Strait

    Georgia Strait Generous Contributor

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    definitely drainage and preserving the building envelope is crucial in my « armchair » opinion

    i have always admired these screens from Comox BC —- (I don’t have one tho I think of it)

    I don’t know
    A. your city building codes rules for fence / privacy

    B. and the respectful ways to use First Nations designs esp on perhaps another peoples’ traditional territory

    etc
    Privacy Screens - Decorative Landscaping solutions

    Also -
    Have you looked at euonymous plant ?
     
  12. Douglas Justice

    Douglas Justice Well-Known Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Mahonia aquifolium is a tough plant that does not flower heavily in the shade, and so, would not produce an abundance of berries. Besides, most commercial landscapers shear the tops off of them, creating an even lesser likelihood of berries (or flowers). But, as was mentioned above, M. aquifolium can get pretty stringy in shade. There are more shade tolerant species—many with wonderful fragrance in the late winter. Mahonia japonica comes to mind.

    I would agree with Margot that Vaccinium ovatum seems to be ignored by rodents, and would seem a good solution, although, as mentioned, it is pretty slow. To be safe, I would seek out a clone other than ‘Thunderbird’, which is self-fruitful and typically produces a lot of berries. Most V. ovatum seedlings don't produce a lot of fruit in the shade. By the way, 'Thunderbird' has attractive, blue-bloomed, great-tasting fruit. There are plants of this cultivar at UBC (it was a UBC Botanical Garden selection) in a couple of the student housing courtyards (these areas are not without rodents) that are laden with fruit every summer. Because there is no irrigation, the unpicked berries tend to dry up on the bushes. I've seen no evidence of rodents around these plantings.

    Aucuba japonica is an excellent plant in dry shade. The variegated ones are not everybody’s cup of tea (certainly not mine), and it’s always been a mystery to me why the green ones (the “best” is probably ‘Rozannie’, which has a GPP designation) are ignored by people. Note that contrary to the GPP image, fruit set is generally low, especially in shade. Note that A. japonica 'Serratifolia', a male clone (GPP lists it incorrectly as a female), is much more vigorous and more commonly available in Vancouver.

    Elaeagnus pungens 'Maculata' and other variegated elaeagnus tend to throw reversions (un-variegated shoots), which eventually outcompete and overwhelm the variegated foliage. Most commercial landscapers do not have the time (or the expertise, sadly) to sort out the two kinds of shoots. This is fine if a green oleaster is okay, but in the final analysis, most oleasters that are subjected to shade will tend to throw very tall shoots, and like Mahonia aquifolium, will end up very leggy, with little foliage on top.

    Pyracantha
    is not particularly shade tolerant and tends to fall over and deteriorate when shaded.

    Cotoneaster salicifolius
    can handle a fair amount of shade, but is programmed to grow into an arching or sprawling shrub 4 or 5 m tall. It can be successfully shortened with repeated shearing, but will end up with bare, stilt-like legs.

    In Vancouver, it's the smaller Nandina domestica cultivars that generally suffer from powdery mildew. In the shade, the larger ones tend to flop. Nandinas also don't shear particularly well.

    It's really too bad that your ground floor person that is so prejudiced against rhododendrons. If it's just the flowers that are so objectionable, I'd recommend planting the Rhododendron cultivar 'Annah Kruschke' (which quickly makes a great hedge or screen, and tolerates pruning and shallow soil) and spending a few minutes each August snapping off the flower buds (they are really obvious and easily dispatched) in this person's vicinity.

    Boxwood is slow in the shade (and pretty boring), but it would certainly fit the bill, if growing somewhat lower than what you might need. As noted, there are disease issues with boxwoods. The following probably warrants a separate thread, but as it has been brought up already...

    As far as I can make out, boxwood blight (caused by Cylindrocladium buxicola) is a rare problem in Vancouver. After the initial positive local outbreak in 2011 and 2012, there have been no official reports since (I would be interested to hear from anyone who knows otherwise). At the time, people were concerned that it was spreading (I was initially among them); however, it looks like what most people are finding in Vancouver is a different blight entirely. There is very little in the way of local research on this, but the more common boxwood problem appears to be volutella blight (a disease often associated with boxwood blight), which is caused by the fungus Pseudonectria buxii. This disease causes stem cankers to develop, which girdle the stems, and these cause the shoots to die in place. The leaves turn reddish then eventually straw-coloured, but they generally hang on to the plant. These dead shoots can be safely pruned out under dry, cool conditions. In contrast, boxwood blight causes ugly leaf spots and rapid defoliation, and is more likely to kill the whole plant. Both diseases are more common where summer temperatures are higher and especially where those temperatures are associated with high humidity.

    The vast numbers of healthy boxwood in Vancouver is, I believe, an indicator of the climatic limitations of the disease, rather than the success of plant health regulations or the exemplary horticultural practices of commercial landscapers. If I'm mistaken, please let me know. Still, never let anyone prune boxwood with tools that have not been properly sanitized and never prune in wet or humid weather. Summer pruning coupled with overhead irrigation should be avoided, as well.
     
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  13. Cantabrigienne

    Cantabrigienne New Member

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    Thank you to everyone who has replied - so much helpful information!

    That's a good idea re: removing buds on the rhodos to prevent the "problem" faced by the ground floor owners - she is quite active in terms of taking care of the plants around her patio so if we make clear that has the explicit authorization to snap off buds on the side of the bushes facing her to prevent the issue of cleaning up wet petals, that might be a workable compromise.
     
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  14. Georgia Strait

    Georgia Strait Generous Contributor

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    what do you think of PJM Rhodo for a “hedge »?

    i like its small leaves and small blossoms ;and odd scent on leaves)

    mine do well near the ocean beach nr Vanc

    P.J.M. Rhododendron
     
  15. Douglas Justice

    Douglas Justice Well-Known Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Agreed. Rhododendron PJM Group plants are wonderful, and I know a lovely linear planting at UBC in a raised planter (with vine maple behind); however, they are highly susceptible to rhododendron root rot in compacted soils. This normally precludes their use in spaces where foot traffic is likely.
     
  16. Ron B

    Ron B Paragon of Plants 10 Years

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    As with heaths and heathers it's typical to see mixed results from 'P. J. M.' in mass plantings on local soils at malls, gas stations and the like. With some okay, some dead, some half dead...presumably there is a water mold involvement under such circumstances. And of course at an oceanside property 'P. J. M.' might be growing in sand. With it being the case that except for specifically wetland adapted species like cranberry, bog kalmia and Labrador tea - to name some locally native examples - heath family plants in general often live in coarse textured, well aerated rooting environments in nature. Even where there are diverse natural concentrations of rhododendron species perusal of collector's field notes will reveal repeated usage of phrases indicating the plants were seen on logs, rocks or bigger trees. Rather than growing in the ground.
     
    Last edited: Dec 22, 2021

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