Those are healthy sized plants and harder to establish than smaller ones. How were they planted and cared for?

tj

I'm not sure how they were planted but we watered them and had them fertilized and cared for by an arborist the last 2 seasons. We thought the first ones died due to lack of drainage at the end of the row so worked on that and they seemed better then they proceeded to die. Our arborist said there is nothing glaring but that they are just hard to keep alive sometimes.

Are we just throwing money away?

Possibly :-) They can have issues. Need plenty of water to establish but must be planted in well draining soil. Deer, squirrels and bag worms can be a problem. OTOH, literally millions of these are planted annually and very healthy, well established hedges/privacy screens are dead common, even with heavy deer infestation.

But there are scores of other plants that could provide the same service. Just need to know where you are located and your local conditions for the best suggestions.

I'm in Collierville, TN outside of Memphis. We don't have any pests or squirrels and the deer cannot get to them due to the fence line.

Then most likely a watering issue. Visit a local garden center and see what evergreen shrubs could work. Cherry laurel and/or hollies are possibilities. I'd mix it up to keep it interesting and to avoid a similar sort of situation down the road.

And unless that fence is a lot taller than it looks, it is not going to deter any deer!! And I can pretty much guarantee a squirrel presence even if you haven't seen them. They are everywhere!

How would it look to replace those dead ones with a different plant? would it look off since there would be no symmetry?

There is no requirement that hedges/privacy screens be symmetrical. The concern would be the replacements' spacing, Few shrubs remain as tightly columnar as arborvitaes and would not fit well.

I would remove the dead ones and simply let the others grow to fill the spaces. They will!

Even if a ‘pencil’ variety, it looks like these may have been planted too closely together. Agree on removing dead growth and leaving space for others to fill in. If you are mulching the area, be sure to leave a ~4-6” gap between the mulch and the base of the trees. Once established they really shouldn’t need too much watering outside of the season’s hot/ dry spells. And, as it looks like you might be in a country setting, it might help to give them some winter protection with burlap.

If you are worried about gaps in your screen, you could widen your planting area across part of the hedgerow (maybe a curvilinear outcropping as you approach the back corner?) and plant some native deciduous shrubs (lots of options— dogwood, viburnum, Annabelle hydrangea, etc) to fill in and add interest to your yard.

And after taking a closer look at your manicured, golf course-like surroundings, it may be worth noting: if you or your neighbors are indiscriminately spraying herbicides/pesticides (causing ‘spray drift’) or applying weed and feed close to the roots of your hedge, that could also be your problem as arborvitae are sensitive to chemical exposure.

What are you using for mulch in that bed? It's hard to tell from the photos but it appears it might be rock. Rocks are generally not recommended as mulch around arborvitae as they absorb heat and don't help improve the soil or help retain moisture. I agree they are planted way too close, too many roots competing for moisture in your hot, humid summers. A good plan might be to remove the rocks, remove the dead plants, and respace and replant what's left leaving twice the distance between them. And get your soil tested before you embark on any labor intensive projects.

IMO way too lose together with no regard for growth Those need breathing room to make sure all sides get light . BTW the deer can jump those fences you show from standing

Yes, herbicide can kill arborvitae. A couple of mine are dead as is a neighbor's. The most likely culprit seems to be the treeless, golf-course lawns uphill behind our houses.

Is your neighbor watering that area too, from their side? You might want to ask them or watch to see how many days and times they are running their sprinklers.