Hemlock is a better bet. Boxwood needs winter protection (even the 'hardy' kinds).

Some of my neighbors have boxwood here in z6b, Putnam County (mid-HV). They survive fine, but one of the things that happens with boxwood this far north is that they develop an unpleasant odor, similar to un-neutered male cat urine. Apparently they have a freeze-survival mechanism that produces an enzyme that really stinks.

I planted about a dozen boxwood shrub liners last year and they survived the winter without protection. I did not notice any odor, but they are growing slowly - a little bushier - nice - but small... On a whim I purchased a golden privet a couple of years ago and it started to take off this year. It's less ugly than regular privet and the deer seem to be ignoring it as well.

I think the odor is what keeps the deer from eating every scrap of boxwood. If you have ANY deer around they will devour hemlock. Look around the woods, notice if the evergreens are "trimmed" up to around 5 feet. Boxwood does fine in the Woodstock/Saugerties/Stone Ridge area. I know several gardens with lots and although you might loose one every now and then, I think the cause is something other than the cold. I usually spray boxwood with "Wiltpruf," waxy stuff to keep the leaves from winter drying. The real problem is there are almost NO evergreens the deer don't eat. Holly, laurel, rhododendron and arborvitae are among their top favorites.

By the way, I don't think there is such a thing as a "barrier for weed seeds." Most will happily take up residence in the middle of any hedge. Especially maple seedlings, aster and goldenrod.

Corapegia, I've heard of hedges used in this way, Christopher Lloyd I think.
I'd rather weed a hedge than everywhere else.
But I need hedges (or walls) for other reasons as well.
I think I'll try a few Korean or "Northern" type
Boxwood and see how they do.
I'll put them by the main deer bypass and check for wafts of tomcat spray.

They never touch my White, Japanese, Scots or Mugo pines,
but I'd like something shearable this time.

I'm also considering large ornamental grasses lately, the deer can
trim them for me :) They've been doing that in the late winters.

I want to try the Wiltpruf stuff on my Pieris and Japanese Umbrella pine
this winter, hope it works, my Pieris take a beating and lose their buds.

Thanks for the suggestions and Boxwood reports.

Large ornamental grasses are safe from deer. I dont understand why they dont touch them but for some reason they leave them alone, and there are some really great ones.