Neighbour politics aside, I would not do it. I may be a little shaky on the science but advice is very, very consistent, which is that dormant pruning should be done as soon as possible before exiting dormancy....common advice is to do it when the forsythias bloom vs. a date as this is a good barometer for this ideal period.

The longer between pruning and the plant being able to respond (i.e., the earlier in the winter you prune), the more likely you are to have significant drying out and die back. Think of your plants in their dormant state as a self-contained system and you are opening it up, allowing all that good stuff out. The tips die and sometimes that can travel back into the plant quite a bit. By doing this right before the plant awakens, the exposed period is as short as possible, and in fact since there is a flush of growth about to happen this is a great time, for the plant, to do it.

This is a different issue, of course, than pruning too late in the Fall, which is that the new growth encouraged by pruning doesn't have time to harden off, and dies. Though the effect is probably pretty similar.

I agree with the above in theory :-) Evergreen plants do not enter a full winter dormancy as do deciduous plants - their growth just slows considerably during this period. And pruning stimulates growth. Fluctations in winter temperatures or the freeze/thaw cycle could encourage growth while the plant is still vulnerable to cold damage.

The best time to prune broadleaf evergreens - any flowering considerations aside - is in late winter/early spring right before growth resumes in earnest. This also allows the safe removal of any foliage or stem growth that has been damaged by winter.

Ask your neighbors to be just a little patient :-) March is not all that far away.

Following up... so if I do trim my boxwood hedge mid-winter, what are the risks to the hedge? Is there any risk of killing some of the bushes or it just stressful for them? These are mature, well-established bushes about seven feet tall and five feet wide.

I'm tempted to trim the hedge if the harm is minimal/temporary in the name of good neighbor relations. The hedge is apparently causing my neighbors to scratch their car paint sometimes. I wish they had mentioned it in the summer or fall, versus in the dead of winter. Now I feel like the bad guy, making a fuss about trimming my hedge in the winter. Arghhh. Input is appreciated!

I think you could safely and honestly tell them that you have checked and it is risky/damaging to do it now, or you would not hesitate, and that you would appreciate their consideration if they could wait until late winter/early-Spring.

Neighbour relations goes both ways! And if it is only scracthing their cars sometimes, since the hedge is not lunging out at them presumably they could simply be more careful or otherwise avoid the situation.

Another thought is that burlapping that side would at least protect their cars.

Though not an ideal time to prune, if your plants are scratching their car I'd say you would be acting neighborly to do at least a light pruning. ;-)

tj

I think I'm going to try holding off trimming the hedge and instead try the burlap approach for now and see if that helps.

The hedge is pretty brown right now already. We've had a rough winter where we went straight from unusually dry and mild/warm temperatures in the fall to unusually cold temps through December and into January (and lots of snow). Maybe that means it wouldn't matter to trim some, but I'm also worried the hedge is already quite stressed with the weather we've been having.

Thanks so much for all of the advice and the words of wisdom!