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.

Okay, I will answer my own question. I went to the hardware store and bought a masonry bit for my drill. I am going to run a few strings along the lower part of the retaining wall, run my ivy underneath and see what happens. Hmmm?

1 - from a design standpoint it's easier to do them both of the same material. Making two different materials 14 ft apart look good isn't easy 2 - to tier or not to tier depends on that specific site and project. Keep in mind that if they're close to each other, two shorter walls are essentially acting as one taller wall. I'm currently redesigning a wall that was improperly built that way in July. I'm redesigning it because it's already failing and the center is leaning 15" out of plumb. Just because someone can stack blocks doesn't mean they can design a wall. 3 - the walkway *can* go up against the wall, but that generally isn't my preference 4 - six of one/half dozen of the other. If you're doing straight runs and no curves, poured might end up cheaper, but it depends. 5 - ehhhhh. The "stone look" walls aren't ever all that convincing. Rosetta probably has the best, but it's also a massive wall system. Where are you in VA that you have Unilock as an option? As far as I knew it's hard to get here. Wall blocks like Anchor or Keystone are almost bulletproof but they're nowhere near "natural" looking. At best they look like a Walmart parking lot built in the 2000s vs one built in the 90s. 6 - There are a couple of quality tiers among the block companies. I would say to let your installer help guide you (assuming they've done a fair number of walls). Some manufacturers are known for slightly less strict tolerances. A block being 1/8" out of square isn't a huge deal when there's a mortar bed. But with segmental walls, where you're stacking one right on the other, that means potentially grinding down every single block to keep the wall level. 7 - A standard timber wall is fine. The metal and timber one, I wouldn't touch without an engineered drawing because it sounds like what's keeping the wall straight is 100% the steel beams. 8 - work with a designer who is product neutral. You want the design that's right for your site, and then we start looking at which product gets that done the best. 9 - look for someone with a deep portfolio. There's a lot of "sure we can give that a shot" out there. This doesn't sound like something that should be someone's first decent sized wall project.

Would probably leave the fencing in place for insurance/liability reasons. I see a shadow that suggests the walls are north/south -- that the sun rises/sets front/back of the house? Easiest and least expensive way to deal with the visual on the front is to plant a hedge of shrubs that will look good year round -- grow thick and keep their leaves. You should also probably waterproof the exposed (middle/interior/visible) side of the front yard. you could do the same for the back wall or the next easiest way to "finish" the center space is to extend the concrete floor of the existing step/stoop and add a full width, high roofed (gable topped) screened porch or sun room, covering the concrete wall sides with faux stone panels. Depending upon what is in the basement and how you want to use this space, you could waterproof just the first eight-to-twelve feet or so of the exposed wall and then remove the rest of the wall and the dirt that is to its left (behind it -- using that dirt to level your back yard) and build a new wall (toward the left/back of the yard) at a right angle to the original wall and have that wall include steps leading to/toward this space from your back yard patio above the new wall (as far away from your house as the new wall extends).