those trees are going to fill the space themselves.. in tree time.. counted in decades ...

and frankly.. from the camera angle... you have the perfect middle tree in the pic...its just in someone elses yard.. lol .. imo.. the best place for a tree .. lol ...

think outside your box ...

what .. in words.. is exactly your idea here.. beyond we lost one.. and want to plant another ...

if you look at your trees.. first 5 feet or so.. you can see how it was pruned at the nursery.. if you look above that.. you can tell the natural way it grows .. and its never going to be as thin as what you bought ...

this is how i look at the future ...

https://duckduckgo.com/?t=ffcm&q=Pinus+strobus+%27Fastigiata%27&iax=images&ia=images

note that they look nothing like the pruned version you bought ...

soooo.. are you open to other options.. other than another allegedly fastigate tree???

a nice flowering shrub might spend 10 nice years in that corner.. before the conifers swallow up the territory ...????? .. or something like clematis along the fence ... etc ...

ken

What Ken said. And to answer your trimming question, no you can’t.

tj

Thanks Ken. I appreciate the comments. We are open to any sort of plant option that would look natural and work for Pacific Northwest style between these two trees. Another type of pine? Another type of conifer? A maple? Probably the reason that I sound so vague is due to my gardening inexperience. We are wanting something that would give a sense of balance to the corner. Similar in height? We only plan to live here for another 5-7 years and would like to enjoy this corner of the yard during that time since we see if every day from inside the house. Here is our view.

I should also mention that we are open to a shrub as well.

You can lop off the top of an Eastern white pine. The tree will then direct one branch upward, which will become the new top of the tree. How will it grow compared to the growth of a newly planting tree? I don't know. In short, if you lop off the tops of your twins and plant a new tree between them, you might still have twins plus one, not triplets.

On my Eastern White Pine, you have to know to look for the signs that we lopped off the top and a branch took over. It was lopped years ago. If you aren't looking closely, you'd never know.

In the long run, your space is too small for 3 grown pines.

In NNE, a viburnum would make a nice, native middle tree. I presume it would in PNW, too.

riddle me this batman .... why would all 3 have to be the same height ....

even if i had 10 matching tress across the fence.. i would relish slight differences in size ... nature is not uniform..and part of the beauty is because of that .. [never plant a monoculture.. so no 10 of anything ....]

yes.. you can prune conifers .. and to do it right.. you will be signing up for a lifetime of guidance pruning.. to get them to grow right .. i know how to so it.. but im not interested in that much work ... and as i said above.. you have two trees that will get huge.. and pruning those back to small size is part of the problem ....

gal and embo are our PNW peeps .... i will leave ti to them for suggestions ...

ken

Here's a mature fastigiate white pine at the VA State arboretum. So.....

that ought to cover the OPs whole yard .. lol ...

Okay. I've been schooled. I will not plant another tree in the middle. I will not plant another large shrub in the middle. I will fill in with some low plants and maybe a boulder or two for interest.