Lakefront retaining wall - need a blackberry substitute

We've recently (2 years ago) bought a lakefront property on Vancouver Island, Cowichan Lake, and have a very messy, sloping, "retaining wall" built of piled-up rubble (chunks of contrete; rock; obviously whatever was free or cheap) that helps retain our shoreline during the winter storms. During the summer, it's high and dry (though we can water if needed). During the winter, the water comes up to the top for 1-3 weeks (usually only once) but covers part of the "wall" (a rock berm backed by soil on the high side really) for most of the winter.

We'd like to make it more attractive, and stabilize it. Currently, it is held in place by good luck and blackberry bushes. We don't like the blackberries as they are a little too high and MUCH too prickly during the summer, when we're there. They are always sending runners into our beach and lawn (ouch!), grab us as we walk down the stairs (ouch!) and are high enough to block views from the lawn/deck. (3 strikes and you're OUT!)

To give you an idea, the blackberries get about 3-5' high each year; they die back in the winter because they get flooded, as noted above.

Local conditions:
- Lakefront on Cowichan Lake so less extreme than inland or saltwater coast locations locally (zone 5?).
- Hot (80-90 degrees F, 25-32 C) and dry during the summer (though we are there and can water if needed), wet and cold (though only rarely below, say, -5 C or 23 degrees F) in winter.
- Can be very windy in the winter.
- Generally snows 1-2 times but melts within a few days. Not usually large snowfalls, 1-3 inches probably the normal range.

Can anyone think of a plant that can cope with these conditions, but not have blackberry-sized thorns and send runners into the beach and lawn? The plant needs to:
- Grow relatively low to the ground, say 1-3'
- Have strong/deep roots that can cope with terrible/soil until they're 2-3 feet deep or sideways.
- Tolerate being drowned once a year.
- Take full sun all summer long.

In terms of look, we'd love Berberis, or heather (Calluna), or euonymus (fortunei, especially variegated), or Hypericum (St John's Wort). But I can't see any of them tolerating the once a year drowning. What about Gorse (Ulex europaeus), or Broom (Cytisus scoparius)? (Maybe too tall? Or would once-a-year flooding keep them shorter as it does the blackberries??)

Thoughts welcome. If we can't find a plant to try (several would be better, we'd try them all in turn across our 90' of beachfront) we could go for all rocks/concrete/river rock. But who wants to look at that??

 

Avoid broom and gorse. They've done enough damage to Vancouver Island ecosystems already.

The difficulty is finding something that will survive the relatively harsh conditions you've set, and yet not be invasive in the local area.

 

As a designer, when confronted with the kind of challenges you face in landscaping the edge of the lake, I look to nature as my inspiration. So, I would check what is growing in the local parks/hiking trails at the edges of the same lake--these are the plants which will do well planted in your lakeside retaining wall.
Some plants that I am aware of that survive this type of site (from landscaping and naturalizing projects around the gulf islands) include wetland grass-like species such as rushes and sedges, sea thrift, wild strawberries (excellent slope stabilizers), small shrubs like kalmia, myrica gale, wild cranberry or labrador tea or larger shrubs like vaccinium (blueberry) or cornus stolonifera. Note that the last two will tend to get taller and may obstruct your view over time; you can cut them back in winter, but this requires a bit of winter maintenance which may not suit you. Also, for the vaccinium to thrive they will still need some water in summer. If you have lots of lake edge and open views, it might be nice to have a section of taller material alternating wtih grasses or groundcovers, to punctuate the best open views.

Presumably the view across the lake is somewhat natural, and using this approach at the edge of your property will tie in with that setting. With more gardenesque and colourful garden plantings kept up closer to the house or built areas, you will achieve a nice contrast and less maintenance over the long term.

 

How about Mahonia aquifolium or Gaultheria shallon?

 

Good looking native plants both, but I was thinking broad leaf evergreens might block the views onto the lake.

NB Mahonia spp. are typically found on moisture deficient sites in nature, so not sure about the winter wet. Gaultheria is the more suitable of the two.

 

Thanks, I'll look into all of these, though it sounds like some are too tall. Most of the natural shrubs we see nearby are too big - and pruning isn't all that practical. First, as we found with the blackberry, you can't reach to prune (the wall is at least 10' wide so you can't get at the middle). And second, we have enough other chores on this large property that we don't want to plant more work for ourselves.

 

The most direct sub for blackberry I can think of that is not prickly nor nearly as invasive is Rubus pentalobus see the postings on this site for more info:

http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=757

There is a creeping potentilla that should grow well in that situation: P. palustris

Fragaria vesca and F. chiloensis are the wild strawberries I mentioned earlier--- we use them for slope stabilization on naturalized areas, and on school grounds because they can take all kinds of abuse.

One other ground cover (creeper) would be Arctostaphylos uva-ursi (kinnickinnick) a native that grows near shorelines in sand and rock.

Or, I would use the grass/bullrush family plants which are perfectly suited to these conditions: Carex, Juncus or Scirpus spp. You can plant small plugs into holes in the retaining wall.

Best of luck!

 

How tall can the plants be, and not block the view?

 

tlpenner

Has got it right. I used to live at "Cow" Lake.
Also look at the more natural stable areas nearby, they will point the way to suitable plants for your location, many areas around the lake can get very choppy water, which will further limit the choices. The Lake being controlled by a weir, has had a profound effect on the riparian plants, by wreaking havoc with the variable water levels. In some areas limestone, is part of the geology, this can help or hinder your future plant choices. Blackberries will be very hard to eradicate from the rip-rap.

 

Thanks to everyone who has posted, keep those suggestions coming.

On height, we don't want anything higher than 2-3 feet - even the blackberries got bigger than this last year and they were beginning to block views.

It's not really a retaining wall, it's a strip of rubble that the former owner linked together with huge chains - mostly big hunks of concrete and river rock but some large logs as well. It's pretty unattractive, which is why we'd like to get something growing on it, but it's essential to protect the bank from erosion. In the winter, it's completely submerged, usually only once and only for a week or two. In the summer it's high and dry. Soil quality is, of course, terrible. We have 90' of beachfront so need to find something that isn't too expensive, and will spread on its own. Plus coping with these difficult conditions.

I mentioned berberis because that is the look and size we're after. Does anyone know if it could cope with our site, though?? (It's generally evergreen in this climate, which would be great for appearance, but I'm not sure how a live plant would cope with being submerged for a week or two. The blackberry mostly dies back in the winter anyway, and somehow doesn't seem to mind being drowned.)

 

I've now looked up most of the plants referenced here. One thing I forgot to mention, there are lots of bears in this area and I want to avoid planting anything that will draw them specifically to our property - they are quite bold (do not run from humans) and we prefer them to stay in the woods.

So, salal sounds ideal, but do bears seek out the berries? For kinnickinnick, as it's nicknamed bear berry, I assume they probably love it. What about wild strawberries? Would that also be attractive to bears?

 

Hi VIG,
Just joined, and found this post, so not sure if it is still active. In response to your bear questions (I work with bears; mostly Grizzlies but Blacks too), my experience is that berry choices are very location specific.

The two questions you need to ask are:
1) How many berries will be produced? i.e. how big of an area?
2) What other bear attractants are available at that time of year?

Bears need huge amounts of berries to fulfill physiological needs - in the order of tens of thousands a day. If you are surrounded by large areas of salal or other berries that ripen at the same time, expect furry visitors. If there are other sources like salmon, fruit trees, or garbage (all much higher 'quality' for bears) then the bears will likely ignore your meager patch.

Salal tends to ripen just before pink salmon runs pick up so can be a heavily used food source in some areas until fish are available.

Kinnikinnik is an odd name - it pales in comparison to Shepherdia berries (buffalo berries) as a food source for bears in the Rockies. It could however bridge the starvation gap in years of poor berry crop. Vancouver Island ecosystems are far more productive so I doubt it performs the same function.

That said, the population dynamics of the black bears around your lake are also very important. Communities tend to attract younger, hungrier bears because the best feeding sites are made off-limits by bigger bears.

Regardless, the time it would take for a bear to finish off your available berries might give you enough chance to finish breakfast while watching it. Just don't go outside to watch - it will increase the effects of habituation which invariably lead to food-conditioning in urban/rural interface areas.

hope it helps!

 

I am wondering if daylilies would do the trick. They're very hardy and I've read that they are useful in stabilizing slopes. They're easy to find at garden centres or at garden-club plant sales, and you can get many plants from one clump. The individual pieces would be easy to plant among the stones/rubble.

 

Carex and iris (not bearded) plants would tolerate/appreciate the water, as would ligularia and petasites.

 

Spiraea douglasii would be a good choice. Rubus spectabilis also came to mind, but it might be a bit too tall and although the flowers attract hummingbirds, the fruits might attract bears if there are enough of them--fortunately, this species does not produce large crops of fruit. Juncus would be great for this sort of thing. Mimulus and Lupinus polyphyllus might like it too. Symphoricarpus albus is another species I've seen growing right next to the water in riparian zones and may also be able to do the soil-holding job, as would Athyrium felix-femina.
As mentioned, eradicating the blackberry will be extremely difficult, especially if you're not there a lot. You might consider hiring a local landscaper to come out once a week and mow down any new blackberry shoots--this will be a long-term project, but it will eventually exhaust the plants' energy stores and deplete the seed bank.

 

Hey there
You need to find either a native lakeside plant that is adapted to flooding, or a cultivated plant that likes those condtions. There are perhaps plenty of plants already growing along your shore you can transplant. The juncus type reeds, and cattails can take some summer dryness. You won't be able to use kinikinic it doesn't like winter wet. If you can get down through the locks into the river it has been taken over by Iris psuedocaris, yellow flag iris This plant is the right size, is toough as nails, takes being underwater, and some summer drought. Your biggest problem will be getting rid og the blackberries. You could also try red twig dowwood, look for a dwarf form, rather than the too tall native. There are some groundcover willows, but they are new and expensive cultivars. Think about pond plants ( marginals), or bog plants if you go to a nursery. Anyways, again, try the yellow flag iris, it is ez, and multiplies without being invasive........yes it has escaped into the river, where it has been for decades