Most likely, the rootballs are dry.

How often and how long are you running the soaker?
Also, is the soaker on top of the rootballs?
- - - If not, please put it there.

I have been running the soaker house for an hour to 1 1/2 each day. The soil seems very wet around the trees. I do have the soaker hose close to the tree base. Do you think I need to run the water for longer periods? Thank you for your help.

Perhaps too much water?? 1 - 1.5 hours of watering every day seems like a lot. Especially if the soil is not well-drained. Did you mix the mushroom compost in with native soil?

I purchased 10 large Green Giant arborvitae this past spring. The tree company planted them but I was right in there helping them dig, and we did not mix ANYTHING in with the native soil, which is well-drained sandy loam. However, I have since mulched them with compost and pine needles.

The company recommended watering with the soaker hose for 1 hour every other day, for the first month. I don't use soaker hoses, but the trees got watered with a good soaking, either by rain or by hand- watering, about 3 x per week. I reduced that to 2 x per week through the season. They seem to be doing okay, although they are losing some needles this fall, which I think is seasonal.

kitababy,
They are in RAISED beds, not planted directly at ground level. Look at the pic.
You are drowning them. Literally.
I have no idea if the soil you planted them in is any good for them, I do know they need excellent drainage.
Browning at the bottom is BAD. It means they are rotting.
PLEASE PLEASE post this in the conifer forum and mention they are in a rasied bed and tell them everything else.
I don't want you to loose them, thats alot of money and work. I have never seen an arborvitae put its top down like that before.
Stop watering for now, and post on CONIFER forum.
THose people are wonderful!

They really aren't mixed with native soil, a little bit but not much. They also aren't in raised flower beds but they do look like it. What we did is we brought in a back hoe and dug up the ground where the tress we're going to sit, then we brought in the good soil, dug the holes and planted the trees. The bricks are just a nice border. I have stopped watering them and I am hoping you are both right and that they are getting too much water...but now we are supposed to get rain. Is there anything I can do to stop the browning? Fertilizer probably isn't wise at this point? I will try the conifer forum like you suggested. Thank you so much for the responses. You are right we have a lot of money planted and I am scared to death I am going to lose half of them

Well, in spite of the various rants, an hour on the soakers may be too little.

Only a finger poked into the original rootball will tell you if the rootzone is wet or dry.

Further, if that mulch is on top of the rootballs, the water is diverted away from the rootball.

Stick a finger in the rootballs to determine what's going on.

For the future, plant in the native soil. Don't add, layer, or mix in, new stuff.

Thank you jean001a, I have stuck my hand in the soil and it does seem moist but tomorrow I will dig to the root ball and see what is going on there, and will keep my fingers crossed.

Crazy how on ever single forum you have people who rante from "a very good soak every two weeks" to " water for 2 hours a day" lol. There's no way there should be this much differentiation. Literally impossible to find a solid answer on whats best

^^^ There is a very easy answer for this, Brendan :-) ALL soils are different so it is impossible to say specifically how often and for how long one need to water newly planted trees without knowing what soil conditions exist. Also, various watering systems will emit water at different rates, further complicating the equation.

The only way to know if you are delivering enough water is to physically test the soil moisture at rootball depth. The soil should be moist to the touch - not dry or not wet. It is also imperative to make sure the rootball is fully hydrated before planting. Unless that is confirmed, it could remain hydrophobic, repelling or resisting water penetration while the surrounding soil stays wet.

Thanks gardengal48! I planted twelve 3ft brandon cedars about 4 weeks ago. The first week I was hand watering the base of the tree with the hose everyday for about 10 second a tree. I couldnt see any water pool up the soil was taking itas fast as I could give it. The very tips of the tree started to turn really light green. I called the place I purchased them from and he said they are probably getting too much water and to dial the watering back to once a week and really really soak them. I've been doing this and now I can see that down low on the tree it's starting to go a dark slight gray color and there are sprouts that are dry and not continuing to grow near the bas as well. The very tops of the trees look good and healthy. Am I being too paranoid? I have excellent soil where I live. It's deep black fluffy soil half inch down to about 18" then it's sand. I've never seen my soil dry more then 3/4" down before