David Cleland wrote:
does redwood (common) still grow even if you do not cut it back to
5cm each spring ?

Do you mean a thing with pretty red bark on upright whippy shoots? If
so, it's red-barked dogwood (Cornus alba), and it'll make a domed
bush about eight feet high if you don't cut it. Lower branches will
root where they touch the ground, so the spread is just about
indefinite.

If you want the red shoots, it's best to cut it down every year (late
February is good), but it won't hurt if you miss a year.

Mike.