What spacing and pruning etc. should be done depends on the intended effect. If a sheared hedge is the objective then quite close spacing as well as cutting back during the early years would be expected to be involved. Otherwise even your current 8 ft. spacing may be too close.

A Jolly 'Green Giant' Spotted at the National Arboretum

'Green Giant' arborvitae increases in height rapidly, growing 1 – 2 feet per growing season, sometimes more. A hedge row of ‘Green Giant’ was planted on the grounds of the U.S. National Arboretum in 1998. At the time of installation, the trees were 3 – 3 ½ feet tall on 6 ½ foot centers. Ten years later, the trees stand 18 – 20 feet tall and 8 feet wide. Not only have they withstood the winter snow and ice here, in Washington, D.C., but they have thrived despite our hot, humid, and sometimes dry Mid-Atlantic summers.

http://www.usna.usda.gov/Gardens/faqs/GreenGiant.html

Fertilizer spikes are a gimmick that raises the purchase cost and reduces the effectiveness. If you have any spikes left and it appears fertilization is called for later crumble these up and broadcast them over the soil surface.

Deer may continue to nibble your trees and keep them stubby for years if you do not install effective fencing. Also unless the animals are excluded damage may be expected to increase during those years when hard winter weather is making them more hungry. A seemingly odd thing is that although deer are native to cold winter climates most of their food supply disappears during snowy weather, so that starvation is routine.

Thank you for responding... interesting about the fertilizer spikes, I had the same feel. Yes I'm well aware of their size . no we have no plans to shear them but if they grow into each other at 8 ft it's okay w/ us. I believe the previous gardener thoughts were to get them to hold steadier in the ground if he cut the tops since they were transplanted... as it were, twice.

You don't say your opinion on what option I listed? I'm curious.. which way would you go?

We will be deer fencing (permanent structure) eventually but for now, I have to wrap every fall.

Imagine there is fencing there now..do they regrow then? Or will they always look stubby regardless?

and here is one to show how they were looking before deer browsing took effect. we are having a pretty mild winter. the deer are just coming right in and eating everything. deer fencing is def. needed. anyone have $ to give for a good cause. LOL

Looks like you used the wrong wire and they can reach right through it. You can fence an area of some size using peeler poles and 10 ft. high plastic mesh made specifically for the purpose, for maybe three or four hundred dollars.

Ah...Ok yup peeler poles! That's what they are called! I always wondered the name. Just googled and that's exactly what I want. Ok, that is the plan. But I want some real opinion? Yank them now? Or keep?? I have 5 -6x healthy (right now) ones that I can keep (& honestly have room for at mature size) The 4- maybe 5x should be pulled .no? or saved?

I'd give them at least several years with no deer exposure plus mulching (grass free area around each should be bigger and kept mulched) before I decided they were a lost cause.

The trees will be fine if left to grow. You can always remove one or two after you see how they out or some may not make it so you won't have to decide on them.

Here's one idea on the kind of fencing you need and no I don't work for menards, I'm just there a lot. The peeler posts would make good corner posts and support between stakes along the fence. Fence Idea:

I'm the OP. Just an update (if anyone is reading & well I feel guilty killing anything alive so justifying it to myself out loud). After much reflection I have decided to remove 2x of these. One is a double trunked one & had deer rubbing on trunks. The other one is just pathetic looking.

Truth be told when we bought these.. the nursery made a delivery mistake & in rectifying it by sent a double order. Of course we were sort of thrilled, since we actually had only purchased 5 originally. But now as time goes on, I really don't like the monoculture look & I'm afraid that's what we have.

Although for the privacy these can't be beat. I'm adding in a duraheat river birch & a red cedar to replace the 2x being pulled. I will also add in time maybe holly or something else so it's not all thuja greens.

I would rather do this now, while the trees are weak & small enough. Can't imagine trying to rip out 20 footers!

I also will be deer fencing this spring (&/or coming fall) since I realize it's all a lost cause if I don't (including any new plantings) Well...just to say thanks to all who responded.

This is all large growing kinds so be sure you are allowing enough room for everything.

Emothrimum You mentioned 10 ft plastic mesh. Can you give us any sources for it? I can't find it! Thanks.

Check here. This nylon fencing material is sold at all our local nurseries and home improvement stores.