I don't have direct experience with that cultivar ('Smaragd'), but many other evergreen shrubs and trees will actually grow taller if planted closely — think of the plants as reaching higher for light. As for irrigation, the same species (T. occidentalis) should take the same watering; the cultivar shouldn't matter.

Nope! I can't speak to best cultural practices in your climate but you can plant these guys pretty close together.

2' is pretty tight spacing.....I'd push that to at least 2.5'. Close spacing will not hamper or encourage vertical growth but it can impact on the health of the tree and the denseness of the lateral growth....which is something you want to encourage if you are looking for a solid wall of green :-)

And actually with this plant the cultivar does matter. 'Smaragd' seems to be far more senstive to soil moisture and susceptible to root rots than almost any other cultivar of American arborvitae. So well drained soil and adequate but not excessive watering.

I don't think I've ever gone tighter than 4 ft centers, definitely not tighter than 3. At 2 ft, I'd also worry about what happens if you lose one down the road. It'd be a hard hole to fill.

As far as a watering schedule, depends on your soil and the weather. As gardengal mentioned it's pretty easy to love Emeralds to death if you get crazy with the watering.

Excellent point about filling the hole should one of these fail. And that does happen :-(

These are as common as dirt in my area and the standard spacing for a hedge - the solid wall of green - is 3' OC.

Verdance LD, I am surprised you are not familiar with these. That cultivar is probably the most widely sold and planted single tree in the US, both as single statement specimens and as privacy screening. Although less used in very hot and humid climates.....not sure I'd include Palo Alto in that category however!

Thanks so much for the help everyone. I will try 2.5 foot spacing and it is helpful to know that, if anything, they will be encouraged to grow even more vertically in the hedge formation. Also, I'll keep up a watering regiment, but not too much so as to avoid root rot.

I will post pics if I get a chance once the hedge is up.

Many thanks!

z6 is vague... is there snow load ... if so.. these can splay when they get older ...

does your ground freeze? .. if so.. during those months.. they will be completely dormant.. as compared to warmer zones ... slowing down annual growth ... i have smargrads 20 years old.. and if they are 8 feet ... id be surprised ... in my MI ...

i would never plant a monoculture ... seems like a season or two..after you declare them prefect.. something happens ... and then you at a min.. end up with a hole in the middle... for some reason.. it rarely happens to end plants ...

and finally.. nothing stops growing at some magical height .... so you will have to maintain them at 12 feet.. if thats your magic number ... and a 6 foot dude ... safely 5 feet up an 8 foot ladder ... is on the edge of defying gravity ... usually with sharp tools ... think about that ...

you dont mention what you are hiding ... and perhaps??? ... focusing at the property line .... a tree between the house and windows ... will accomplish a lot more.. faster ...

ken

look at Thuja occidentalis 'DeGroot's Spire' ... as a thinner alternative ...

planting close is not relevant .... the faster you want a screen.. the closer you plant things together ... i just dont see.. on that factor alone.. that there is a problem ... but there are all the other issues ... with intensive plantings ... and surely.. 6 inches is not a significant difference imo ...

and.. btw ... splaying is a function of multi trunked plants ... that cant hold themselves up .... a majority of that can be avoided by having single trunked plants ...

ken

https://duckduckgo.com/?q=Thuja+occidentalis+%27DeGroot%27s+Spire%27&t=ffcm&iax=images&ia=images

Do you want the hedge to have a uniform appearance, or still look like lots of individual plants? I always find that because of its more compact form (vs. T. occidentalis), 'Smaragd' never really seems to grow together into a solid hedge. That may just be my experience, however.

Here is Thuja o. 'Smaragd' planted on 30" centers in Ottawa, IL. (zone 5a) in August 2016. Photographs were both taken in August of 2017. This will be year three and they are nearly filled in completely. The amount of this cultivar seen in landscape environments is staggering but there are instances where it is the logical choice based on its narrow habit. Snow load can be a problem on more mature plants.

@Ken_Adrian mentioned 'DeGroot's Spire' which is one of my favorite cultivars but difficult to find at a suitable landscape height.

Side Note: The whimsical bicycle rim flowers were initially part of a public art display along a bike path in Griffith, IN.

After as much as 20 in. of snow this past Feb. fastigiate or otherwise closely upright branching conifers of all types can be seen with splayed open tops just about everywhere one looks in my area. (We do not get regular heavy snowfalls). So you can expect your 'Smaragd' hedge to have similar problems at some point.

Thanks for the great help everyone. Just got the cedars in the ground today. I did staggered planting at 24" centres. Hopefully splaying and root rot don't get the best of these trees.

What sort of watering schedule do folks prefer for these for the first year?

I use once a week , making sure the root ball gets wet enough , like about 3 gal. each

ron

Does anyone know the “spread growth rate?” of these? I see the height growth rate in every article but not the spread rate. I have just planted several of these,somewhat mature at purchase at 4.5’ high, and close to 2’ wide at purchase, i spaced 2.5’ apart and am anxious for them to fill in. Comments anyone? i wish landscaping sites would post the width spread growth rate regularly!!! that would be a huge help to the general homeowner doing DYI landscaping. Pic included (excuse the bucket of dirt, i am not finished yet!! Before i began digging the holes i red spray painted pot sized circles then dug out circle slices and used them for ”sod” to fill bare spots where i recently had an overgrown buggy pear tree removed. i just planted my DYI “sod” yesterday yesterday, two are still sitting on top not planted yet, and the spot needs several more, i will continue to fill it this way when i dig more holes for my new shrubs. i hope it takes!! Thanks!!

i would probably cut those sod pieces into 2 or 3 inch plugs.. and space them over the whole area so they will fill in faster ...

i hope thats all native soil.. and not grindings ... too much wood will give you watering problems.. and lack of nitro as the wood breaks down ... try to work in native soil ...

conifers are trees.. and you better start thinking in tree time... which is counted in decades ... yours will fill in nicely ... if you give them the 3 to 5 to 7 years it will take ... the first year or 3 will be growing a root mass.. to start working on height and width ...

as trees.. they will never stop growing.. not only up.. but also across ... but it will take years ...

please look at the link below.. especially section one ... it really isnt tree planting time for most of us ... but then.. i dont know where you are ... you can always hold potted stock over until the proper fall planting time ....

i would also suggest you diversify your plantings ... just in case some future problem rolls thru and has the potential to wipe out all of one thing ....

you could have started your own post ...

ken

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

in ken's link about planting , it will say to dig hole 2 to 3 times the size of the pot

that is to loosen soil and allow roots to penetrate and aid in drainage

get some mulch around them and water weekly for first year

ron

Ken & Ron, thanks for the tips. yes Ken where the tree was removed i had the stump ground up so there was alot of wood in there but i painstakenly raked and rmoved alot of it and root pieces. although I am sure there is still wood in there. i actually did purchase 2 bags all season organic Nitrogen fertilizer a few weeks ago.

Hello Dale, I'm about to plant the same tree for a hedge and would love to know how your hedge is look 3 years on and how much privacy it gives after 3 years. We're wanting to get a fairly private hedge in a couple of years and wondering about planting the Thuaj in a double row to achive this...advice anyone?

Thanks!

This was taken in March of 2022. Not the most objective of photos because it is hard to account for my height with taking the picture. My guess is over 3 years I got about 6"-8" of height per year. That might speed up as the tress should now be well rooted.

The double row is ideal if you have the space. If one dies it is less disruptive to the flow of the hedge to replace.

The most important thing with these big box Emerald Cedars is to MULCH WELL. I top up every spring to keep 3" of mulch underneath the tress. They are all really healthy and I have had none die. In the summer I water them with a soaker hose when it gets dry.

My guess is I have another 4-5 years until I get some decent privacy from the neighbours.

My guess is over 3 years I got about 6"-8" of height per year. That might speed up as the tress should now be well rooted.

Apart from the narrow habit meaning that when a platoon of 'Smaragd' is deployed a lot of them have to be bought and planted it is actually a slow-growing choice. Otherwise, what dwarfs the tops of field grown trees and shrubs during transplanting is the involved cutting back of roots. Unless stock purchased is in quite poor condition when installed or stunted afterward by final planting site characteristics the normal (previous or nearly so) rate of top growth should be resumed following the first autumn after planting. Because 60% of the annual increase in length of existing roots of cold climate adapted woody plants occurs in autumn. With generation of new roots from cut root ends occurring when top growth starts in spring. So that with determinate growing items like pines for instance, where it is easy to see each year's increment of top growth a typical scenario with a recent planting is a long stem section dating from when the specimen was still growing in the fields of the production operation from which it came. Where particular methods were employed to push stock to size up as fast as possible, enabling more crops (and hence more income) to be gotten from each acre. Followed by a much shorter increment marking when digging for sale occurred. And then if enough time has elapsed since replanting an immediate return to significantly longer shoots being evident the very next growing season afterward. And not three years later, as is often stated.