Thank you both so much for your suggestions! I tried to take some photos to show the light conditions now that the leaves are out. This is in the morning, and there's some sun filtering through, but I can tell you there's almost complete shade from the stone wall at the back to about 15-20 ft. in front of the large maple tree all day. From the picture in the next post, you can see there's shade well into the parking lot as well. However, I'm really glad to hear you both think 10 ft. should be sufficient height. Yardvaark, you make a good point about competition from the small maples. So, I think we'll take those out, and possibly the smaller of the hemlocks as well. Then, put in a mix of evergreen and deciduous shade-tolerant shrubs/small trees that reach 10-12 ft with staggered layers for depth. I'm also somewhat relieved you said 'it's not a formal solution'. That means I should just relax since I can't really make a mistake! Lazygardens, I've wondered what the huge rhododendrons people grow around here were - I guess 'rhododendron maximum' is it! Regarding the fence, it's a good idea. I'm not really a fence person, but if we put in smaller, slower growing plants it's going to take a while to screen with greenery, so the fence may be the best short-term solution. Then we can take our time building up the plantings. Yardvaark, I really like your idea of testing out a few small varieties first to see what does well and then increase from there. Cheaper that way, too! Let me know if you have any additional comments/suggestions based on the new pics. Thanks again for your help!

Plant them on at least 6 feet centers. It would be even better, if you desire a faster privacy screen, to plant two staggered rows of them with each being planted on 8 or 10 feet centers, and the staggered rows with holes that are dug at least 6 feet between the front and back rows. Water them well, but if planting in a clay soil which is not elevated or otherwise draining well, monitor them closely to ensure you do not allow their roots to suffocate by sitting in too much water. Also do not let the roots dry out too much. While the trees are getting adjusted, do your best to keep the soil evenly moist, but not soggy. If you want to feed the trees do not use anything more strong than the slow release 4 month lasting, non-burning Osmocote. This fertilizer can even be mixed into the planting backfill soil without burning the roots. In October apply more osmokote by spreading it under the trees and gently scrape small amounts of the top soil and mix in the fertilizer. Also spread cedar mulch under the tree if your soil seems to dry out too quickly. If the trees become stressed and their needles growing on the lower branches begin to yellow, do not cut off those branches; not even if they begin to appear as though they have died. You can remove any dry needles you desire, but do not cut off any entire branches. Just like most arborvitae trees, Green Giants will not regrow any branches, which you cut further back than anywhere the needles have been growing out from. When any branches have appeared to die, take the time to determine if your tree needs less water, more water, or a better watering system. Once you correct the problem and the tree becomes happy again, it will begin to produce green needles again on those once dead appearing branches. Also do not let dogs urinate on any of your Green Giant trees. These trees will begin to die if a medium to large size dog has consistantly been allowed to use them as a place to urinate on at least for several weeks. If your trees are sheltered from the cold winter north and northwest wind, or if they do not receive too much winter direct sun, they might stay green all even all winter. Otherwise they could turn a redish or burnt brown color over the winter months. If this happens do not be alarmed, because once Spring temps warm and rains arrive they should green back up nicely. I have noticed that Green Giants which stay green year round seem to gain more growth height throughout the year. Green Giants which struggle by being planted in poorly draining situations, and or which turn red in the winter seem to grow much more slowly. If these manage to survive they will spread and grow thicker trunks and their top growth will be so slow that the trees stay fairly nicely filled out from top to bottom. The fast growing trees often begin to send up a growth shoot which appears much more sparce than the bottom parts of the tree. When this happens, if you give the tree a feeding of osmocote the trees will, over a short time, begin to fill out the top growth to be more in balance with the thickness of the lower, older developed part of the tree. Do not cut off any of the thin looking shoots that burst forth at the top of your trees. Each thin shoot which begins to grow out of the top of your trees is needed for the trees to grow taller.

OK .... i have green giants... that i started from 6 inch peat plugs in 2001, or so .... and abused them greatly .. lol ... they are about 15 feet tall ... and about 5 to 8 feet wide.. and are just getting rolling .. no tree/conifer ... is going to magically stop growing ... on my 5 acres.. they are going to be just great ... especially when they are 30 feet tall by 10 feet wide ... or 15 ... i was thinking your yard was a bit smaller .... but i cant see it .. so you are going to have to decide... if they are of proper proportion to your yard .... are you willing to give up 10 or 15 feet .. back where you want to plant them???? white pine .... ALWAYS ends up shedding lower branches... as it get 30.. 40.. 50.. 60 .. 120 .. feet tall ... you can leave them .. but they can get really ugly ... and then you are left with big stinkin trees... but not the privacy you wanted .... are you willing to give up this much space???? please.. consider this .... YOU DO NOT HAVE TO PLANT ALL OF ONE THING .... do two pines... do a few GGiants .. and a few spruce.. etc ... diversity rules .... and if somewhere down the line.. some dont please you ... or get too ugly .. you remove just those... but still have the privacy you want... and keep in mind ... trees planted... half way out to the property line... can be correspondingly smaller.. to offer teh privacy you want .... no one says.. privacy barriers have to be lined out at the fence .... a picture would sure help .. good luck ken

There are other grasses besides bamboo that would be good fast screening. Most have to be cut back in spring, but they grow up fast. Grasses are cheaper than evergreen plants usually. I have a giant reed grass that I think is attractive, but I am already sorry I planted it. I think it will spread and invade. Bamboo can cause problems. Other grasses are tall enough and common enough to give you privacy. Click on this photo and see if it will go to my album. Nathanael Greene Close Memorial park in Springfield, MO has a beautiful grass garden.