I planted a rather extensive arborvitae hedge about 3 years ago -- about 40 plants, overall length must be about 200 feet. They were 6-footers when purchased, and they have grown in really well. They're now about 9 - 10 feet tall, and almost wide enough to touch each other. I have not pruned these at all (yet).

My goal is to have a solid hedge for privacy, but still be able to maintain it myself, with a hedgetrimmer and step ladder.

So the question is, when should I start to prune, and how? The big thing I am worried about is height. I have seen some arb hedges that have grown way, way tall and can't be maintained by the homeowner any more. I don't want that to happen.

Will I cause problems if I "top" the arbs? How can I keep them from growing too tall, without injuring them or creating some other problem? Should I trim the tops frequently (like once a year)? Or is there some maximum amount to take off, like "don't trim more than a foot off the top" or "don't prune more than 10% of their height" or some rule of thumb?

 

Understanding pruning arborvitae.
http://www.aboutarborvitae.com/pruning_arborvitae.shtml

Here's a site on when and how to prune an evergreen.
http://www.emmitsburg.net/gardens/ar..._evergreen.htm

See 'Pruning Junipers and Arborvitae' here.
http://cmg.colostate.edu/gardennotes/618.pdf

Pruning dos and don'ts for conifers.
http://www.conifersociety.org/cs/mod...e0687804397b4f

Some good info here on pruning hedges here starting at the bottom of page 10.
http://www.hort.purdue.edu/ext/HO-4.pdf

You might also find this video helpful.
http://www.finegardening.com/how-to/...ght-edges.aspx

Newt