British Columbia: Augmenting soil for new native plant garden.

I'm creating a new berm area for native plants, roughly 12 x 6' in a mostly shady part of my yard. I'm trying to make it look natural so I added a tree stump and am looking for tree trunks and large rocks to form the border. I am guided somewhat by hugelkulture, that is, using rotting wood, leaves, sod, etc. The concept behind hugelkulture is that the rotting wood adds nutrients and bug cultures to the soil and the decomposition process warms the soil thereby extending the growing season. It also helps to retain moisture in the soil thereby reducing water needs. The final layer will be soil mixed with compost.
Huglekulture is used mostly for vegetable gardens but I thought the principles were applicable to my project. Any other ideas on soil for my semi-woodland garden? I have Vanilla Leaf, Salal, trailing blackberry, Trillium, Falsebox, mahonia nervosa and oxalis as ground cover. For trees and shrubs I would have liked a conifer as an evergreen feature, but the natives are too large. I'm keeping an eye out for a Garrya Eliptica or ?? Vine maple ??

 

1. Due to the frequency with which I see honey fungus in plantings here I would never add stumps and logs to a planting.

2. Since this is not, in fact a vegetable plot fiddling with the soil like one does for vegetables is not the best approach; I would either plant in the existing soil and mulch afterward, call it a day or bring in a layer of topsoil, spread it out - without any intentional mixing with the existing soil - and plant in that, mulch afterward.

Do not incorporate organic amendments into landscapes destined for permanent installations;
topdress with mulch instead

http://www.puyallup.wsu.edu/~linda ...ltural myths_files/Myths/Compost overdose.pdf

3. Coast silktassel does not grow wild north of southern Oregon because it is tender, even wild specimens are sometimes burned by cold winds - it is much more of a Californian floristic element than a native one, when you are talking about native to the ecoregion that includes Vancouver Island. The closest-growing tall native broad-leaved evergreen shrub is Pacific wax myrtle, this also hugs the outer coast in nature but seems to last mostly quite well in plantings much farther inland. Otherwise the common tall broad-leaved evergreen, widely distributed and growing in a diverse set of circumstances is tall Oregon grape. There is also coast rhododendron and evergreen huckleberry, both are frequent in cultivated settings here.

 

Thanks Ron B. Given the poor state of plants in this old neglected garden, it certainly appeared to need organic matter, but I hear you. I thought that mimicking a forest floor with it's fallen branches and rotting organic matter would be good for my plantings, but, as you say, adding mulch on top of soil is probably better. I still have at least a foot more to build up my berm so the rotting material I've already placed should be nicely buried.

I know this is the very northern reach for Garrya elliptica but I've seen a few mature specimens around Victoria, most recently at the Native Plant Garden in Oak Bay, that seem to be doing very nicely. The native rhodo is notoriously temperamental here and not easy to come by. I have both the evergreen huckleberry and tall Oregon grape planned for this site, but I'm still looking for an 6 to 15' evergreen shrub or tree to be the feature of this garden. If not, I will consider Vine Maples.

 

Pacific wax myrtle is a new one for me. It looks interesting and apparently can tolerate some shade. Thank you.

 

Coast silktassel has been grown for years down here also but there is occasional damage, it is best as a wall or sheltered courtyard shrub. And, again, not really a native - it doesn't even grow wild on the northern Oregon coast, let alone in BC.