What are the downsides to planting privacy screen trees (i.e. green giant arborvitae) too close? What is "too close"?

JayTree

New Member
Location
Somewhere
I planted 30 trees in October. 8 feet on center and 5 feet between rows. This left 6.5 diagonals. The effective head on spacing looks like every 4 feet.


The pictures are at bad angles to see the spacing but the goal was a compromise to get faster screening and be healthy into maturity. But I really thought 40 foot maturity... now I'm reading more about 50-60.

I do need a tall SCREEN. Ideally grown together up to 25 feet so can block neighbor's house on a hill (deck and windows) that is 35+ to roof.

At 40 feet, I felt confident I could prune them narrow over the years so they were 20-25% width to height. So that's 8-10 feet and gives me a screen without too much crowding.

But another 20 feet and they will need to be wider and could crowd.

What is the risk at that point?

Should I consider transplanting this fall? Or is a few more feet not worth the shock if they are doing well?

I would likely move to 12 feet since I could leave a few. Most would need to be moved though.

They'd gain only 1.5 diagonal but 4 feet between rows. But for 60 foot tree... does that make a huge difference? I would think root zone wise it won't really. And they all get full sun.

What are the downsides I'm facing if I'm too close? And do you think I did plant them too close?

Of course the fact that I might not even live to see them at 60 feet (I'm in my mid 30s) should be a consideration. But want to leave the trees to serve the future generations!

What do you guys think?
 

oldoakman

Well-Known Member
Location
Alorgia
My son in law planted a double row8 or 10 feet OC and row 8' apart on a 1400x 400' property line. They are 20-25x tall and a green wall with a tunnel between. They do an awesome job.
 

JayTree

New Member
Location
Somewhere
My worry would be high winds knocking them over when they’re taller.
Would the extra space help significantly? Is this because they'd each have a better root system individually? I'd think they'd all still root out similarly just be intertwining more if closer... which could help them be even stronger? But maybe not. That's just my uneducated guess.

I will move if needed. I can't afford much space between rows. I don't want closer to the fence and want to keep within line of shed.

But could space them further. I'd only be moving them ~4 feet over so I would think I could dig the holes first and then sort of slide them over even. It'll stink to need them to re-establish all over again but perhaps not if I extend out enough to capture where their roots grew this year?

But will that 4 feet make a difference in their strength and stop them from blowing over? Or is it effort and transplant shock for no good reason?
 

JayTree

New Member
Location
Somewhere
My son in law planted a double row8 or 10 feet OC and row 8' apart on a 1400x 400' property line. They are 20-25x tall and a green wall with a tunnel between. They do an awesome job.
This makes me think I did mine too close then. I definitely won't get the tunnel between since mine are close between rows. They'll grow together they way. I can't really space them further front to back though. Not 8 feet anyway.

Curious if you have pictures and could confirm the spacing?

If I were willing to sacrifice some some along the front line of shed where I want to extend out gravel drive (will be replacing mobile home with barn)... I could get away with not messing with back trees and just moving trees in front row. It's an idea.

The curved row I'd like have too tight a curve and need to remove 1.

I know there's no perfect answer.

But wondering my answer of 8 and 5 was just wrong. I'm also grappling with thinking how much could a couple fee matter when it comes to a 60 foot tree. But heck, you need draw the line somewhere.

Why is 6 foot the common row recommendation if it's too close?
 

Tom Dunlap

Here from the beginning
Administrator
When I was in school my landscape design instructor taught us to use an 80% of listed full size for spacing if you want a mass planting. Soon enough you’ll have a solid mass. Spacing further will leave slots

If you plan on fall transplanting you could do some root pruning now. Given their age I doubt that it would be worth the effort. Before transplant time get in a watering regimen. Having them hydrated and the deeper soil wet will reduce stress

You could do some research on soil additives for root growth. For that small area the cost will
Be low
 

JayTree

New Member
Location
Somewhere
When I was in school my landscape design instructor taught us to use an 80% of listed full size for spacing if you want a mass planting. Soon enough you’ll have a solid mass. Spacing further will leave slots

If you plan on fall transplanting you could do some root pruning now. Given their age I doubt that it would be worth the effort. Before transplant time get in a watering regimen. Having them hydrated and the deeper soil wet will reduce stress

You could do some research on soil additives for root growth. For that small area the cost will
Be low
So then did I space correctly on that design?

80% of 60 mature height is roughly 40. Base on the 40 height and trimmed to 8-10 foot width so they are a bit more column shaped... it leads me to the "solid mass" screen I need up to 25 feet or so. Anything further apart starts creating gaps where there isn't privacy from my neighbors windows.

Any reason for that rule of thumb? I'm all for it since it means my spacing is okay ha. But curious to understand.

Heck, ideally I could get them to stop growing at 40 feet and my spacing! I just want to block the view entirely to 25 feet and the roof and rest of the house blocks above that doesn't need to be complete screen.

The house is likely 40 feet up given 2 stories + walkout basement + roofline. Rather look at wall of green then a house. That's the goal. Just don't want them falling over or dying after 30 years due to poor planning. Be it for me or future generation (not sure these live long enough to be multiple generation trees)
 

Tom Dunlap

Here from the beginning
Administrator
Realistically pruning and shaping will taper off as years go by

The 80% height and diameter rule of thumb I learned in ‘75 has been validated by observation over the years. Closer and the will grow together and get ‘hollow’ from shading. Further and you never attain the solid mass planting

You’ll have to do your math and scratch your chin
 

JayTree

New Member
Location
Somewhere
Realistically pruning and shaping will taper off as years go by

The 80% height and diameter rule of thumb I learned in ‘75 has been validated by observation over the years. Closer and the will grow together and get ‘hollow’ from shading. Further and you never attain the solid mass planting

You’ll have to do your math and scratch your chin
Curious what you think of these drawings:


This shows the 20-25% width to height ratio and how they will grow together as they get taller. It actually makes me realize that even at my spacing it might take longer than I'd like to get them together.

Sure, at 60 feet they are monsters and grow together for 40 feet of their height. It looks worse than it is since I'm showing head on effective 4 foot spacing. They are staggered so not quite so close in reality.

But perhaps they will never quite get that tall.

The 30 or 40' drawing is near perfect to me. I do need quite a tall screen but they aren't too badly crowded at those heights if pruned narrow.

I definitely can't prune forever but hoping I can train them over first few years so they don't get too wide at the bottoms.
 

JayTree

New Member
Location
Somewhere
A few photos of my son in law's double hedge.
Thanks for showing me that!

Looks great. Hope mine look that good at some point! If his are 8 foot on center than it does show that being at least that close helps screen higher up. They don't look unhealthy at all even grown together.

How long did they take to get that height?
 

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