We have 11 beautiful mature thujas planted along our driveway and they have started showing sings of stress after our horrible Toronto winter (drastic temperature changes, loads of snow and an ice storm). The thujas look very rough, with sporadic dry spots (see the pictures).
We are new home owners, are are not sure how to help them out. We'll be very grateful for any suggestions
Honestly, there's not a whole lot you can do. They mostly have to take care of themselves. They are pretty tough and probably will. If you are not getting enough rain, you can give it a really deep watering, like put the hose on very low and just leave it for 24 hours, moving it to different locations. You don't want to do shallow watering or fertilizing. Thuja tends to be shallow rooted anyway, you don't want to encourage more surface roots.
If some of those branches turn out to be really dead, you can clip off dead branches where they leave the trunk. Otherwise, you have to be very careful about pruning thuja. It does not re-bud on old wood. If you prune an arborvitae too severely, cutting in to the old wood, you create a permanent bare spot on the tree. So just cut dead stuff off. In late spring, (about now), you can remove crossing or rubbing branches, which can create an open wound, Just clip one of the branches back to the next lateral branch.
@rainbowgardener: thank you for your advice! We will prune them slightly just to give them a better shape, but will be careful about overdoing it. I don't think the previous owners fertilized these trees, would you suggest we do that anyway just to give them a healthy boost?
No. 1) you never want to fertilize any plant/ tree that is stressed. The fertilizer just acts as another stress, forcing it to grow, when it needs to just heal and recover. 2) like I said you don't want to fertilize the surface, which is what fertilizer usually is. If you really want to feel like you are doing something, you could mulch the whole area with compost or just bark chips. That will slowly break down and seep into the soil, but in the meatime helps hold moisture in the soil. Just don't get any mulch too close to the trunks. Leave a bare circle so the mulch is a few inches from the trunk all around.
