This was posted to show the damage done in high heat. It was a 2 1/2 year old shrub that had done well until the summer of 2022 when temperatures consistently went over 100 degrees for weeks on end (109 the highest). It had been well watered, so drought was not the issue. It was however facing west and received the hottest sun of the day. The species Thuja Occidentals (eg Holmstrup), I've now read, can take the cold, but not the high heat of a southern summer, unless perhaps in partial shade. T. Orientalis or T. Plicata are reputed to be more heat tolerant.

That is sad to have that happen. Were you in a drought in Oklahoma last year? Even though you state the tree was well watered, perhaps the earth below the plant was still extremely dry and roots didn't get enough moisture. At days over 100 degrees a lot of the water probably evaporated instead of penetrating deeply into the ground. Hope there is some chance of recovery.

No, it was not a water situation. The back side of the Thuja that faced East stayed mostly green, the front side which faced west was burned. As it sits today after winter, the East side still has mostly green, but the front (west side) has dropped almost all its needles. Doubtful if it will grow new ones. All across town there are dead small Arborvitaes that look similar. Holmstrup seemed like a marvelous solution for a short upright evergreen that would stay in bounds. Unfortunately, it was too good to be true in our harsh climate.