The message
from "DLee" contains these words:

Hi All

We planted rows of Leylandii under the fence facing private street this
summer. As thefence is quite long, we needed about 20 Leylandiis, but even
with that, about couple short to finish off the hedging. So we planted Thuja
Plicatas(we had these from months ago in large pots..) alongside Leylandii.
Now Leylandii has grown about a foot during the summer, but Thuja has not
grown that much. Would this be problem later? We thought Thuja and Leylandii
have similar growth speed, but arethey really?

cheers

Dan

The catalogue for Buckingham Nurseries reckons about 2ft per year growth
for Thuja and 2.5 to 3 ft growth for Leylandii. If you intend to keep
the hedge to a certain height then eventually you can let the Thujas
catch up and keep them both cut to match.
They will always have rather different textures though.

Janet G