When an arborvitae becomes too big, but still has enough interior greenery to make cutback feasible, we can cut it back. However, the gardener may have to accept a lower standard of appearance for a year or two. We grit our teeth and cut, unless other options are open. Perhaps a design can be altered to let the plant grow, or replacement/starting might be feasible.
These two arbs had grown to press in on the stairway landing and close off the view from the deck. They were crowding a crabapple on one side, a Japanese maple on the other, and encroaching on the lawn, seeming to demand that the bed be enlarged. We cut them back by about five feet on top, and twelve to eighteen inches on the sides. We expect to cut them again in two years, removing only 12 inches and six inches.
After a hard cut, the trick is to keep looking at the plant, checking its health without regretting what might be a marginalized appearance. Plants that have suddenly lost a great deal of leaf surface may be unable to manage on their own when beset by problems that were trivial when they had more energy.
We call it shaking hands with a plant, to look at it closely, to observe for insect damage, discoloration, and anything else out of the ordinary. When and if we see anything that seems unusual, we hit the books to determine what's afoot and if we need to intercede.
If you cut a shrub back because it's just too big, and it dies, you haven't lost anything but a plant that couldn't live by your rules. - Janet -
They waited until he went out of town and then they thinned the trees. He didn't notice for nearly a month. - S.M. -