We had a similar situation in our backyard. We planted arborvitae, which did very well along our side fence, in pretty dense shade. However, in the past few years they have been decimated by deer. If you don't have a deer population passing through, arborvitae should work well. We used Canadian Hemlocks along our back property Line, which also has a significant amount of shade and competes with other trees. They grew quickly, but after their third year, they were attacked by wooly adelgid (an aphid-like disease), and in spite of our efforts to save them, they are looking pretty bad, and I need replacing. I'm told that Hemlocks are not susceptible to disease, but my experience was not good.

If you do not want to install a stucco fence, if city code allows intall a short electric fence along the back property line to discourage wild animals from invading and eating your landscaping. Then Plant two rows of Thuja Plicata Green Giants in a staggered pattern for the entire length of your house. Plant all the trees on 10 foot centers, and be sure to dig the planting holes for the back row of trees at least 6 feet away from the easement. Also, space the center holes for the front row of trees at least 10 feet infront of the back row. X,,,X,,,X,,,X,,,X...X...X...X...X...X...X ...X...X,,,X...X...X...X...X...X...X...X county drainage easment, county drainage easement As you can see from the planting example created by the rows of Xs above, it will take 21 trees planted on 10 feet centers to cover each 100 linear feet of your back boundry that you want to plant with Thuja Plicata Green Giants. If you want to plant them for nearly the length of your home and and if that linear length is more than 200 feet, then you will need to plant more than 42 of these trees. If you wanted to plant the entire 400 yard linear boundry line than you will need to plant 84 of these trees. If you can purchase 84 one gallon sized potted trees, purchasing that many should be much easier on your budget. For each of these one gallon size trees you choose to purchase just predig holes 3 feet wide in diameter by 10 inches to 1 foot deep. Also pre install a drip watering system with outlets, which once the trees are planted, can be positioned to water each tree individually. A high graded quality one gallon Thuja Plicata Green Giant tree should be anywhere from 12 to 18 inches tall and have a well filled in pyramid shape. If the winters are mild in your part of California, then one gallon trees that are watered correctly and given slow release non burning fertilizer at the beginning of each growing season, should be expected to acclimate fairly quickly and grow at least 6 to 12 inches during the first year after you plant them. The next year if you have been good to keep them watered properly, and fertized at the approprate times, they should grow at least an addtional 3 feet. By the end of the 3rd year if you have still kept them watered at the right amounts, and fertilized appropriately, then they should have grown an additional 5 feet. That means your trees by the end of the 3rd year, could at the very least have grown to be about 11 feet tall. By that time, it is possible that they could have spread enough, if you planted two staggered rows to almost be giving you a solid wall affect for at least the 4 feet up the trees' height. Every year there after they should grow at about 5 feet, and as long as you keep them fertilized properly their skinny new top growth should keep filling out at a fairly nice pace. Other wise if the trees are not fertilized at the beginning of their growing season, but if they get the right amount of soil moisture, they will grow taller, but the new growth will look thin and sparce, while taking over six months or more to ever fill out with a well balanced branching pattern. If your trees begin to take on such an appearance, by all means resist the temptation to snip of that thin up shoot of growth. Instead simply begin feeding and watering the tree properlly and it will respond by producing a nice amount of branches on that upshoot of new growth and also, follow that with more new height growth. With these trees, always remember that any branch you cut off at the trunk will not grow back, so if for any reason the lower branches become brown due to the tree not getting enough water, or the tree's roots suffocating from too much water, do not cut those branches off to the trunk. So do not purchase trees which have a lot of lower trunk showing. Also if after plantings the trees encounter too dry of soil and begin to brown. Do not prune away the brown branches. Instead you can remove the dead needles if you would like, and simply begin making certain the tree gets adequate moisture. Then be patient and if you have begun the better care paractices in time, you can be assured the tree will grow new green needles on those bare dead looking branches you left on the tree. If the tree's lower branches begin to die due to soggy soil conditions which suffocate the tree's root system, you should wait to see if these dead looking branches will recover, with proper care of the tree, but in that situation there is not such a high chance these will respond as well as desired. If you plant a wall of these trees, than to prevent them looking boring consider planting a variety of shorter and not to broad of spreading ornamentsl shrubs planted and spaced appropriately infront and lined up with the middle of the front row of tree's spacing. At the feet of the ornamental shrubs you could install a border planting of continuously flowering, or very decorative leafed one to two feet tall potential growing plants or shrubs.

" ... but it is also potentially boring." But that's why there are other places in the yard and they require different things instead of a continuation of the singular screen. BTW, a screen has the duty of a wall. It visually and physically separates side-by-side areas. It is not a ceiling, floor or opening. (Later, it will become a ceiling, too, but that's not the reason for its implementation.) I don't think the question of the exact word it's called -- a "garden" or a "landscape" -- makes much difference in what solutions work best, though it may indicate how people feel about their outdoor space. In the USA almost no one refers to their outdoor space as a landscape, but call it the front or back yard. The people who are plant lovers may call it a garden. But just as often as not, if one is really into plants (as many people here are) they tend to sacrifice appearance for plant acquisition, collecting and hoarding. I must confess I have no idea what "showing feelings for plants" would look like. To me, all the materials that are used in assembling a landscape ... are materials. Yet that hardly makes me (or many others) immune to appreciating their beauty when well put together and especially, for the plants when they age well. I don't think the crabs are going to be any smaller than Amelanchier. 3 large shrubs (grown in the tree form) would screen the back neighbor's house. ... Lilac, beautybush, certain Viburnums, Burning bush ... that sort of thing.

I have a mixed shrub bed that is probably 15’ x 60’ and am in a similar zone. If you want arborvitae or Rhodies, just plan to spray with a deer repellent. Some are oil based and some can be mixed with a substance like Wiltpruf to prevent it washing off so that it only has to be renewed every few months unless there is new growth. I second the comment about blue spruce not being worth a long term planting in the humid east. Mine after 10 years are bare on the bottom and losing needles and shoots on the top, so I will take them out in the next few years. My preference is for having a rhythm of repeated characteristic plants down the length of the bed rather than clumps of one kind, and then I fill with variety. Here is a thread where about half way down I added a couple of posts with photos and an explanation of my plan and goals, so rather than rewriting the whole thing, I am sending you to the link. https://www.gardenweb.com/discussions/3113384/shrubs-for-privacy-along-a-fence#n=22 I have listed plants I used and even after 10 years I am generally pleased. Some plants have not done well (Pieris and Cornus are much beloved by the voles and don’t live long without roots) and as mentioned above, the blue spruce are disease prone. By now many of my groundcovers and perennials have been shaded out. Right now it needs editing, but I have spent the last year dealing with a terminally ill family member, and it has done surprisingly well with quite literally no maintenance. I will do some editing this fall when it is a bit cooler, and if you can find dwarf versions of other evergreens that are less popular with deer if you don’t want to spray, that would be good. My Norway spruce which isn’t in my shrub border, while lovely, at something like 25-30 years, it is huge, perhaps 25’-30’ wide and well over twice that tall. So if you want to use a spruce, look for ones that grow more slowly. For instance, there is a slow growing version of Serbian spruce/Picea omorika as well as one that looks bluish, so look for those. I went to all the nurseries in my rural area and chose from what was available that suited my needs since I wanted somewhat larger starting plants. One of the fastest growing plants I put in were panicled hydrangeas, and between their ability to gain size quickly, their need for little attention after the first year or two, and their months long bloom, I would use these again in any similar garden. I deliberately used more than one color and texture of evergreen for winter interest, particularly during the long fall and early spring when there isn’t snow. My cover photo shows a piece of it during this stage if you click on my name. If you have questions, feel free to ask.