hard to tell on this pic..

but if it were me.. i would go 3 to 4 feet back.. and plant a whole new sight block.. presuming its your property back there...

and in a few years.. when it is doing its job..

get rid of these ugly old things...

the problem with inter-planting.. with these very old mature trees.. is that their root competition is going to make survival hard.. for new transplants... unless you are there to perfect moisture thru the whole root zone... for a year or two ....

i took me an hour.. but that is a boat thingee at the bottom.. and if this is the cottage.. and you wont be there all the time.. then the water management could become a problem ....

i would bet my shiny nickle.. you might not even get a shovel in the ground there .... and by the time you dig holes in between them all.. they might fall over ...

is that wall new.. heavy construction can do a lot of damage to older trees.. i wonder also.. if they might not fail entirely.. in the next year or two ....

think outside your box.. of working between them ...

and... shrubs is a common term.. these are actually conifers.... and if you want suggestions on replacement conifers.. i suggest you try that forum ....

ken

If you're going to cover the fence, plant in front of it rather than between the multi-trunked Thujas. They look like candidates for removal as Ken says. Why inherit someone's mistake and all the futile work and expense of trying to correct it.
Mike

Thank you both for the response. It really helped and I really appreciate it.

oh come on... is that a sea wall for the boat dock >?>???

inquiring minds want to know.

is there space behind,...

dont leave me hanging out here w/o followup ...

what i really want to know.. do you think those trees are cracking that wall ... or is that a camera trick.. that is the first question that needs to be addressed ....

ken

Sorry, that is a hammock in the corner. The wall appears to be fairly old and appears to had rails at one time. You can barely see the metal posts that were cut off about an inch above the wall. It seems to be in pretty good shape with only a minor crack that is further down from the plants. It runs part way across the back (about 60'). I have over a 200 arborvitae in the yard (lining driveway and streets) and the only ones that are cut like this are on my back patio (9 of them). The ground is full of roots so I am thinking I am SOL on planting anything around them. I just was hoping for something that could fill in here because they are about 20' tall and would be a great privacy wall if only someone didn't go crazy with the pruners.

Also, the yard behind is mine but I didn't want to look at those ugly trunks from my sun room and back patio that is why I was hoping to plant something that would cover them.

Sorry one more, the things that look like cracks are actually some remnants of what appears to be an old vine.

hmmm... bummer on shooting down my seawall theory .. i will be depressed all day long ... NOT!!!... lol ...

you might want to think about pots.. and proper media ... so as to avoid the whole root/watering nightmare ... perhaps the container forum could help you there.. along with the annual/perennial forums ...

pots in winter in z5 ... can be a little tricky ... but not really hard.. once you understand .... an afternoon of work in late fall to protect them for winter ....

but i still dont understand.. why you could not go 4 or 6 feet back into the lawn.. plant some shrubs.. and when they get to the height you want.. to just get rid of these old crumby arbs ... i am not sure you understood what i was getting at ... it will take a few years.. but at least you are working toward a goal ... rather than hoping for the quick fix ...

ken