Posting this again with pics per request of Ken. We are in Zone 5 not far from Denver Colorado.

We are starting in on planting trees and shrubs in our back yard. We had a master landscape design done for our entire property which has helped us a lot with hardscaping decisions and narrowing down our plant wish list. But we are wishing to add more screening trees along a 54’ section of fence where we back up to a two story neighboring house.

We can widen the planting bed along that fence to 10-12’ because we want to reduce and re-shape the existing lawn. Some columnar trees we are considering that seem to do well in our area and are sold by a local nursery are :

Bruns Serbian Spruce
Scarlet Letter Oak
Kindred Spirit Oak (another neighbor has two that are thriving)
Taylor Juniper
Parkland Pillar Birch (just a couple in the wettest corner)

I’ve researched mature height and width of all of these and we have also observed and photographed them around town when we can spot them. I believe their mature sizes would work in the space and we are open to bringing in an arborist periodically once they get big if we need help controlling some spread.

I’ve read the advice about not planting a monoculture. Would love to hear your suggestions on:
(1) How many trees to put along this 54’ fence and which ones
(2) How to group them - staggered groups of three or ?
(3) How far apart to space them.

We realize this is an investment of many years before trees are big enough to actually screen, but it’s an investment we are willing to make. We live in an area where fields are being turned into housing developments and there aren’t a lot of trees, so we’d like to contribute toward the future beauty of the community and property.

I’m attaching a scale drawing of back yard plans, original master design (done two years ago), a sort of fanciful concept drawing by yours truly, and some photos. Thank you so much for any insight you can share.