MICHELLE H. wrote:

The type of fence is a 6 foot high wooden spruce stockade fence. The
reason why we want to plant the Arborvitaes all the way down, is because
we need a screening that is MORE than 6 feet tall. We want something
that is about 9 feet tall or more to give us privacy from VERY nosy
nextdoor neighbors.

I'm sure everyone figured out about nosy neighbors

Spruce is as cheap a lumber material there is... it'll rot before most
nursery size arborvitae grow higher than the fence. How tall are your
neighbors that they can peer over a 6' fence? If they are so nosy
that they are intent on spying nothing you plant will help... in fact
arborvitae will make their spying easier, all they need do is peer
through while they are hidden from your view, they'll be able to spy
unseen from a shorter distance so they'll have a much better
telescopic view... your arborvitae will afford your neighbors more
privacy than they afford you. And many are under the misconception
that plantings grow as perfectly described/pictured in catalogs, they
definitely do not. If you plant the typical nursery sized arborvitae
(3'-4') you'll be at least 10 years older before you have a wall of
greenery, and still there will be gaps. I can never understand folks
who want privacy and then buy a home on a small city lot... ain't
gonna happen... and if spying neighbors are in a two story house right
nearby they will always be able to peer down on you. Whatever you
plant be sure to plant far enough away from the property line that the
branches don't grow across or neighbors will be within their right to
trim them. As arborvitae increase in height so do they increase in
girth, at ten feet tall they'll attain minimally five feet in
diameter... providing they receive full sun from all directions. If
your plantings will be shaded by that fence then forgeddaboudit... if
you've ever walked in a forest, especially a conifer forest you will
immeditely note that there is no foliage except way up at the top of
the canopy. For privacy you really want to plant a double staggered
row, you'll need at least a ten foot wide swarth so light can enter.
And still there will be gaps, there will always be gaps. Probably,
other than moving, your best remedy is a better fence.... and you can
steal a bit more height by nailing your fence sections about 6" higher
on the posts... it's good to have a space at the bottom for weeding,
if the fence sections touch the ground they will rot, and that space
can save your fence from strong wind gusts... you'll also more easily
spot neighbors creeping up to peer through your fence because you will
see their feet.