Fight drought with mulch, mulch shades the soil. Sun bakes the water out of bare soil, you can actually seeing it rising in the air and dissipating. Your watering will go farther with mulching.

The problem with flooding the plants and then letting them go dry is you don't want either to occur. Flooding may drown and kill roots, drying out completely is also detrimental. You want to water so that a moist, yet aerated condition is maintained. Stick you finger in the dirt, buy a moisture meter - do whatever you have to in order to learn how to provide the planting with even moisture throughout the growing season.

What kind of arborvitae did you buy? If these are a fastigiate or columnar cultivar like the highly popular 'Smaragd' - the emerald arborvitae - which often or normally produces multiple trunks of similar size you will not be able to cut all but one without destroying the specimen.

Unless these plants are still quite small, you might be able to try it with those and have it work out.

As with any other trees or shrubs, cutting away a bunch of the top will have a retarding effect on growth for awhile. If you cut too much off or leave big wounds failure may even result.

you said: My plan was to water deeply with a soaker hose once a week

=======>>>>

you water when they need water ...

plant them properly .... ask if you dont know ...

mulch them properly ....

and then water when your finger.. inserted to the 2nd knuckle.. tells you the soil is hot [aka dry in a day or two] or actually dry ....

watering is an art .. not a science .... meaning it is not a schedule thingee ....

you can not project how much water your soaker will put down in a given time.. nor how that water will move thru the soil .. plus all other water-soil variables ...

it is more important to get water throughout the entire root zone .. all thru the part you planted .... rather than many superficial waterings .... it is not only important to get it that deep.. but that it drains out of there in the long run [the clay soil issue] ....

in my pure sand.. recent transplants.. get thoroughly drenched at planting.. and with mulch.. MAY not need water again for a month ... surely not every few days ... how that works in your soil is the real issue ...

now.. by the end of summer.. if you were to keep notes about your finger and its contact with the soil ... MAYBE you will find out that 3 hours of water.. will be good once per week ... but otherwise... you are simply speculating about it all ...

we can not really give you an answer about that part ...

BTW .. where are you.. is snow load an issue???

and what is your soil type .... clay vs sand is two differing worlds.. and how you plant in said circ differs wildly ...

USUALLY ... we would not do severe pruning on a recent transplant .... but a picture might be worth a couple thousand more words of speculation ....

GOOD LUCK!!!!

ken

Why cant I cut the side branches off of emerald green? My understanding was they are better with a central leader but most nurseries will grow them with multiple so they grow fuller. but for the long term growth of the plant one central leader is best.

In a separate matter...

I have one one in sandy dry soil and part shade and it hasn’t done much in years and lost all its lower branching which I eventually cut off due to all the lower foliage dying... I’m moving it to a sunnier area ... but it also had cedar rust ? on it this past year (orange goo) as we had multiple junipers in our yard that we have since removed ...

the thing looks pretty pathetic right now and no matter where I move it, it will eniveitably look like a lollipop if it recovers and flourishes

i was thinking removing the side shoot might give might give it a better chance

Start a new post with pix for a better response to your questions. Also note that thuja is not a true cedar so not a host to rust.

tj

I personally enjoy the ”architectural” look of an older Thuja ‘Smaragd’ or ‘DeGroots Spire’ with multiple leaders. If you’re not in a portion of the country with heavy snow loads where splaying could be an issue, I say let them do their thing.