spacing is only an issue in regard to your goal ... which you dont state ..

if you want prime individual specimens.. plant them 20 feet apart ...

if you want a site block.. plant them as close as you like to accomplish said goal as fast as you wish it to be done ... the closer the faster ....

otherwise .. sounds like the job is done.. whats to worry about ...

ken

this is how i look into the future: https://duckduckgo.com/?q=thuja+green+giant&t=ffcm&ia=images&iax=images

Ken_Adrian,

My goal is a TALL screen but healthy and long living. Admittedly, I'd like them to grow together up to 25 feet or so. We have a neighbor with the house elevated and essentially 3 stories tall. The last ~10 feet of roof don't mind seeing between the tree tops. But really want to block the rest.

Based on the shape of a 40 x 10 tree with fairly consistent narrow pyramid shape, my spacing head on with effective 4 foot gaps seemed to work for this. The overlap covers ~60% of the height or nearly 25 feet.

If I were to move the spacing out to, say 12 feet, it seems like not much (still get 6 foot gaps from head on and now closer to 8 foot diagonals) but it's closer to 40% overlap so only ~15 feet. Not ideal until you get closer to 60 feet. The diagonals at 8 feet would also be worse.

I suppose I should consider my own enjoyment of these trees and not just the long, long term. Even getting to 40 feet probably won't happen for another... 25+ years. But if it will be sad if beyond this they keep growing and are unhealthy and die off. I certainly don't anticipate them being pruned beyond training to be narrow early on.

Heck, while I'm certain they will get to 40 feet. Do they manage to really slow down and not get 50-60 feet? And hell, I could be moved on or dead at that point.

And then... does a few extra feet really make a difference for the health of the trees?

The U.S. National Arboretum presents Thuja 'Green Giant', a large, evergreen sentinel in the landscape

https://www.usna.usda.gov/assets/images/as_standard_image/Thuja_Green_Giant.pdf

Embothrium... The ones in that picture are what I'm looking for space was. It's not a pure hedge but they are pruned fairly narrow and on close side so nice screen. What distance were those planted?

Another image I had found that shows the more narrow look:

https://www.thetreecenter.com/c/uploads/2014/06/thuja-green-giant-2.jpg

But I guess none of these are showing full 60 foot height.

Do you think my 8 and 6.5 (diagonal) spacings are okay?

Here are pictures from planting in October (angle taken makes it difficult see 8 and 5 foot spacing).

https://m.imgur.com/a/DXfGdSP

Like ken said , you already planted them ,,,,,so..

I was advised to cultivate around them for first few years - good for roots

mine were spaced 8 ft,,,now about 30 ft tall

pic from 4 yrs ago

Those look great. How long ago did you plant and how big were they? Any other pictures? Have they slowed down or do you think they will get to 50-60?

What zone are you in?

I did already plant but can always dig them out and transplant.