It depends on the nature and extent of the brown to issue a certificate of death. There is no way to diagnose the brown from your pictures way up there looking down from google satellite images.

Yes, in addition to closer pix, how about a little history. When and how planted, after care, recent weather, that sort of thing. Ferts will not help.

tj

Yes, need to know we’re these B&B or in a pot? Did they receive extra deep water this summer when we had our heat wave in PNW? Just an observation but they are planted too close together. Should be at least 4’ apart on center. Yes,even for a privacy hedge! Too close & all you have is a bunch of brown dead stuff where no air or light gets in. These look like the typical “Emerald Green” arborvitae that‘s generally used for their bright green & nicer texture.

Some nurseries guarantee their plants for a year. It appears you planted these yourself, as they are too close together. Give them some time to come back, but if you need to remove a few, it will give the others room to grow.

Where are you and when were these planted? And if a tree is dead, it's dead :-) No coming back from that one!! But from the distance of the photo I don't see any obvious or serious browning so maybe much ado about nothing....closer and more detailed photos required. The biggest thing with the planting of new arbs is making sure they get enough deep watering their first year in the ground.

The spacing looks dead-on to me. I spec and oversee the installation of dozens of Emerald Green arbs every year and the standard recommended spacing is 3 feet on center.

I must have missed where the OP mentioned they were in the PNW....or is that just a guess?

Hopefully he didn't plant them six inches above the soil level and forget to water them.

Gardengal48 - OP didn’t mention locale - it’s my guess. Check out the huge firs i& looks like water n background! Also, where else but in PNW do we see Emerald Green arbs planted as green screens everywhere? I’m not an expert as you seem to be but I’ve had better long term success with spacing 4’ on center when planting larger size as these seem to be. It gives them room and air and they do fill in to touch but not crowd. It does take longer. Also - to the OP‘s issue, I think the ones that are browning are gone. It happens often as I’m sure you know - especially when not watered deep & consistently the first couple summers.

if you are not a pro.. and you planted 40 and ONLY lost 3 ... sounds to me.. like you are doing pretty good ...

we need all the ???s above answered .. including big city location before we can go any further ...

ken

btw ... if that is supposed to be grass in front of them in the second pic.. it looks like severe drought in your area this summer ...

ken

well thats a new GW/H trick.. because i know i did not post that comment above.. twice ... id delete the duplicate.. but then.. well.. both might disappear ... lol ...a double dog new trick ...

ken

My house is in Bellevue, WA. I tried to keep the trees watered this summer but I don't have an irrigation system so there's lots of room for human error.

I planted the trees with Miracle Gro Tree Soil. Unfortunately at the time of planting, I didn't know to mix the soil with compost or soil. I planted the trees 36 inches apart (on center). I bought trees, in May, from Costco and the tag on them said to plant the trees 30-36" apart.

Here are some close up pictures.

Christopher C Nc, tsugajunkie z5 SE WI ♱, KW, gardengal48 (PNW Z8/9), ken_adrian Adrian MI cold Z5, please see responses to your questions above and excused my delayed submission. It's been a very rough few weeks.

Emerald greens on greatplantpicks.org site

rfharmon, see the info at the link above. It doesn’t address how to successfully plant these but is good info specific to our NW. This site is a wonderful resource & maintained by well known Seattle master gardeners.

About your trees, Costco is a great cost effective source for them but understand the plants are stressed & not watered while in store so the sooner one buys them & plants after their arrival in store the better. Your description of how you planted them may be the cause of current problem with die back. The existing soil should’ve been mixed well with amendments like compost only. The roots should’ve been ruffled up a bit to free them from the container shape. If they were B& B ( balled & burlapped as field dug) the twine & burlap should’ve been removed. If this was the case & it wasn’t done it‘s worth digging around them & pulling all that off. If they haven’t been in ground a full season you could actually pull them out & correct the soil issue & replant! Because trees are at bottom of slope, water runoff from top might be causing problems & in this case, make sure they aren’t planted too deep. Should be no deeper than where soil level at trunk was. For the first couple of summer watering challenges, soaker hoses are a must! For your length, a couple of separate sections would be best for water pressure. Hose should be wrapped around each tree a bit away from trunks. Water slowly & for couple hours to water deeply.. Start process after spring rains stop. The challenge is that die back can also be caused from too much water & clay soil not amended & plants drowning bc the roots are sitting in a tub of water. If you remove any trees do check the soils under the bottom for this. if dead limbs are limited to one upward stem / trunk, you can cut it off for now & see if it fills itself in from remaining stems. If all trees are planted too deep or not deep enough, more dieback will happen. Take heart bc it’s not uncommon when planting a line of emerald greens to lose a couple for any / all of above issues. Good news is that you can replace them. Do know that the back sides of these trees against the fence will die because of lack of light. Some limb these hedge trees up because of that & either leave as is or plant interesting shrubs in front. I had a row of 8 planted & lost 2. Had 4 on each side of 3 weeping cedars. Replaced 1 lost with a butterfly maple to provide color, texture & didn’t replace the other as didn’t need it. That‘s another idea is to break up the line with something else for interest. These pics from spring 2016 Hope that things have settled down for you now. We could all use a very long stretch of less drama!

The closeup pictures look like you have had some stem dieback. Cause? Countless options. That makes them only half dead. Yes you can cut out the dead parts and give the remaining living part a good amount of time to fill the gap - depending on all else being in good working order.

Like ken said - if you planted forty and only three are having issues. You did good.

KW gave a very thorough answer of all things to consider.

KW, what is the groundcover in your first picture?

Christopher C NC, that ground over is “Brass Buttons” Leptinella squalida ‘Platt’s Black’. I love it, had it at my last home too. Many guests who care not much about flora except that it’s pretty, comment on it’s ferny soft appearance. Dogs love to lay in it & chose over prickly grass - softer on the belly. Teeny yellow flowers are reason for name but they’re innocuous - can’t see unless looking closely & no scent. See info at Greatplantpicks.org llink Brass buttons

BTW, I enjoy your posted pics of color around your neck of the woods when I stumble across them on this site!