I believe I just ID'd these as the Oriental Arbor-vitae.

all are dead but the last ... unless they turned yellow last year.. full sun pix are a problem on some level ...

when was the last time they were repotted.... media wears out ... making water and nutrition issues... and those are rather large trees... in small pots ...

ken

They yellowed within the last couple months. I have no clue when they were re-potted last, they are at my work so I don't have much wiggle room for re-potting. :-( Why did the first two do so badly and the third is fine? The all receive watering 1-3 times a week depending on the Arizona heat and are all within 10 feet of each other.

Niquole, in a potted plant, the pot is for all intents and purposes that plant's entire universe. In other words, if it got too dry one single time, there was no option for the roots to grow downward further into the soil, etc. They had only the confines of that pot from which to sustain life.

Plants like these can be grown in containers, but let's face it-they would do better in the ground. In any case, the dead ones are dead, and presumably, will remain dead!

Too dry. Not enough water in a porous pot for the heat they endure.

Mike

I'm not sure the last one looks 'happy as a clam'. It has browning tips and interior. The one in the background under the roof looks on its way out too. How are these things watered? How often and by whom?

You no longer have evergreens, but rather everbrowns. They're dead Jim (Trek reference)

They are ex arbs.

Stucco behind, stone below, in a container in the Arizona sun...they cooked.

tj

Ah, yep, have to agree with Flora - the third one also looks severely stressed. Can you replant in the ground?

Thank you so much for the answers! My boss is talking about replacing them with something else. The person who took care of them before only watered once a week during the summer and I took over in October. It's hard to replant the existing plants since they are at my work and not my own.. :-(

"The person who took care of them before only watered once a week during the summer....."

See that right there Niquole. Plants do not run out of water on some man-made schedule. Particularly in pots, the only way to know for sure is to check. A finger inserted into the potting mix, or sometimes just picking the pot up (if it's not too heavy) will tell you its moisture status. There just isn't any substitute for actually checking. And potted plants dry out fast. There was never any way that once a week was going to be enough.