River birches can get huge. We have a number of them on our property, and while I love the look of them they're very messy trees, shedding small branches year-round. If you want trees that will only be as high as your blue outlines, I'd rethink both of your choices. We also need to know where you're located to give you other ideas.

My blue outline doesn’t represent height. That’s simply the location they will be planted. I have no maximum height. I would let them go, I’m simply more concerned they might really encroach on my yard or swing set, but I know they can be trimmed at points to limit that.

Hi svengoli:

I'm noticing that the size and position of the happily growing Kousa Dogwood (or similar) on the left in your picture would completely screen the neighbors that you intend to block out, if a couple of them were planted at your blue markings. If you don't wish to repeat a species, there are quite a few species that grow to similar stature and can provide further seasons of interest (Redbud, Crabapple, Asian maples, Fringe Tree, Styrax, Stewartia, Tree Lilac, Red Buckeye - the list goes on).

If it is the two species you mentioned or nothing, I'd lean to the River Birch - despite Bookwoman's admonitions. They do grow quickly, much more so than Sugar Maple. They will likely have less ground level competition with other species (less dense shade and less dense near-surface root system), so maintaining a lawn or other woody plants beneath it will be easier.

Forgot to mention, I am in NJ zone 7.

Dogwoods are lovely but grow soooo slooooow. I also love river birches and have 2 in my yard. They drop branches, most of which you can easily run over with the mower. I also have an older maple which drops much larger branches. I’ll get some photos of my birches tomorrow- they are huge and we’re planted 15 years ago.

I’m at a loss here. Since they will be planted near the fence, I would prefer to not have an issue with my neighbors in the futures with these trees becoming huge and wide.

What are the existing evergreens/conifers on the fence line now? They are not going to like more shade. I loathe all the falling twigs from birch trees. Like ViburnumValley, I'd be rethinking the tree choices all together. A pair of Japanese maples seem more suited to the situation.

I'd be looking at much smaller trees--Halesia, Amelanchier, Redbud (Cercis), deciduous Magnolias.

i dont understand ... are there power lines back there??

or a line of light bulbs close to the camera??

is that a con trail way back there ... or a utility ...

you have a huge lawn ... is there any reason you couldnt come 15 or 20 feet into such.. and plant there ...??? why are you limiting yourself to the 3 feet at the property line??? think outside your box...

that said.. a tree 10 or 15 feet out from the patio/deck.. would make a sight line block decades before the trees at the property line ... usually its the privacy you want on the patio ... not when you are mowing the lawn lets say ...

if this is an option.. we need pix of the patio/deck for ideas in that regard ...

ken

Echoing Christopher - what is planted along the fence line now? I suspect that those trees will provide great screening in the next few years. They may be planted too close together and too close to the fence. They will out,grow any new trees you plant. Attached are 2 pics - a river birch which was 8-9’ tall in 2006, and a row of Leland cypress trees that were 6-7’ tall in 2006. The doghouse under the birch tree is about 5’ tall. This tree is large enough to provide afternoon shade for the pasture to the left of it. The cypress trees screen my property and the neighbors.