Forgot to mention we are in Western Mass. The privacy buffer will be on the south side of the house. Lot's of sun with no shade.

Thanks.

I was reading a post that was similar to yours, even though they had a high fence and yours is low. They live close to your zone and there were a lot of good ideas on it. You may want to check it out.

Here is a link that might be useful: Suggestions for trees along privacy fence

I'm guessing your neighbours might be violating regulations about pool safety if their fence is low, but that's another issue.

If you use plants you'll need quite a few of whatever you use. If budget is an issue, as was mentioned on another thread, watch craigslist or freecycle, or buy in fall... or indeed, use something that roots easily that you can get cuttings of, maybe from someone who has a big mature bush.

You need to decide what features you want the plants to have - evergreen vs. deciduous, what height, how much maintenance.

Have you considered a privacy fence?

KarinL

We also needed privacy along a property line. I wanted something fast growing but also evergreen as I wanted year round privacy. We decided on Green Giant arborvitae. They do not look like the typical conical shaped arborvitae, but are a little more open, airy, and free flowing. From my research they are virtually the only variety that are deer resistant. They were about 18-24" when planted last April and averaged a foot of new growth last year. When established, they are supposed to grow 3-5 ft per year. They do need a lot of watering the first year or so until they get settled. With this past hard winter, we had some significant deer damage on half, but hopefully those will recover and I will spray with deer solution just to be sure.
We ordered from The Botany Shop
http://www.botanyshop.com/index.htm . Prices were really good and tree condition on arrival was great.
Hope this helps.

Thank you for all of your great ideas. Kazoonative, you mentioned something I didn't consider but I'm glad you pointed out: year round privacy. The Arborvitae might just be the way to go. What's the major difference between The Green Giant and Emerald Green? How far apart did you plant them? Do you think 10 will suffice for 40-50 yards?

The Emerald Green is a fuller more conical shaped tree from what I've seen. They grow 4-9 inches per year once established (a slow grower) and are not deer resistant. They are a thuja occidentalis - a cultivar of the eastern white cedar. The Green giant grows 3-5 ft per year when established (a fast grower)They have a more open, free flowing appearance and are thuja plicata a cultivar of the western cedar. Check out these info pages: http://www.nurserytrees.com/Arborvitae_What_You_Need_to_Know.html and http://www.botanyshop.com/GREEN%20GIANT%20FACT%20SHEET%201.htm
Hope this helps!