I've recently 'rescued' from the dumpster 4 large boxwoods.
Two have a trunk size of about 1/2 - 3/4 inch and stand about 2
1/2
feet. The other two are much older and larger with trunks
twice that
size. They were 'problem bushes' at a local landscape company
and
were waiting to be claimed by some fool ... and i was there
with $5
a-piece for them! All i've done to them so far is trim off the
brown
parts ... not alot. What i'm left with is dark, shiny green and
vigorous!

Sounds good. Boxwood are pretty tough trees.

I've got some questions:
I know i'm going to eventually chop things shorter ... can i
air-layer
to get some more nice trunks on boxwoods to work with ?

I suppose you can, but anything you cut off a boxwood and stick
in the ground (with or without rooting hormone, though it helps)
will root as a cutting, so I wouldn't bother with layering. I
have rooted 2-inch stems. I just jam then in the ground
somewhere out in my garden.

How short can i cut them, and be assured of bud-back?

Leave some leaves.

How soon can i start pruning them?
How should these big old bushes over-winter?

These last two questions go together. You have already pruned
them. Since they've suffered considerable trauma this summer, I
would not do anything else to them until next spring.

As for wintering, we don't know where you live, so it's hard to
give serious advice. But, since they appear to live OK as hedges
planted in the ground in your area, putting them in the ground
over winter probably would be your best bet. Failing that, put
them in a large pot. And since, for boxwood, they don't sound
THAT big to me, a cut down (8-inches deep) 10- or 15-gallon pot
should do OK if you can't get them in the ground.

Anyone got some published info on Boxwoods as bonsai ?

Billy gave you a good reference. Google for "boxwood bonsai"
(include the quotes!) and you will find more. It is a commonly
bonsaied shrub.

Jim Lewis - - Tallahassee, FL - The phrase
'sustainable growth' is an oxymoron. - Stephen Viederman

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