Trees grow best when not pruned! Pruning removes resources that the plants use to produce new growth. As you said, dead (and diseased, damaged, and rubbing) branches can be removed at any time.

Maybe you have something else in mind that isn't apparent (at least to me) from your questions. If so, pictures might help us to better understand your goals and/or the specifics of your situation.

Yes, especially given the species involved ("pine" and Green Giant Arbovitae) I am interested to know what it is you want to do before being able to give the best advice.

Yup^ and yep^^. Aside from some specialty applications, like a sheared hedge, or a purposely dwarfed pine, these two plants look best when pretty much left to grow naturally.

Dead wood can indeed be safely removed any time. The best overall time to prune trees-if they actually need pruning-is late winter/early spring. Other acceptable times are mid-summer, any part of winter, and late fall. The two worst times are spring, during the time of bud expansion, and fall, during the time of leaf color change/drop. During both of those times, trees are undergoing physiological changes to prep for the coming season, and pruning then can mess with this process.

BTW, I have long noticed people really like to prune stuff in the fall. So much so that it has passed into the popular mindset that this is the time of year to do so. I am convinced that this has happened because people like to be outside doing things in the fall!

+oM

Hehe, yeah I'd really prefer to prune in the fall, cuz its more comfortable. Unfortunately I know better :P

gw409, I hope that you've understood the message here...pruning just for the sake of pruning is frowned on. However, many of us prune to enhance the natural shape of a tree or shrub, or to limb up a tree when the branches begin to hang too low. Growers of fruit trees prune carefully in order to open their trees for improved light penetration. Pruning can be done to direct growth and to stimulate growth, but those applications are the exception rather than the rule.

I wish that more growers of woody plants would spend ten extra minutes on their plants when they are still very young...pruning away those major flaws of infrastructure when it can be done with handpruners rather a chain saw by the property owner a few years down the road.

The two plants you've mentioned aren't pruned under normal conditions, and perhaps you're wondering about that. And it is never advised that woody plants be top pruned when being transplanted. The energy manufactured in the leaves is crucial to the rapid development of new roots.

Also, the new growth that will be stimulated by the top pruning will also be at the sacrifice of new roots. Woody plants simply cannot respond to a major assault on the roots AND the top at the same time.

I suggest that you post pictures of your trees and list your goals for them. Maybe we can provide some constructive suggestions.

objectives

green giant arborvitaes -
planted about 2 years ago, currently about 8-10 tall, some of them do not look as dense as others and i thought trimming the new top growth by about 1'-2' would help stimulate lateral growth and density.

white pine-
one planted about 2 years ago currently about 5-6 tall.
this needs to be moved to a different location this fall. not yet having some of the knowledge i have gathered on this forum, last week i cut the top 9"-12" of new growth in anticipation of the upcoming fall transplant, thinking it would help the transplant process by giving the root system less to support, and also help stimulate lateral growth.
(oops rhizo)

additionally
i needed to cut off some small branches from established/older appx 8"-10" diameter pine, maple, birch trees that were too close to the roof or starting to shade and crowed some newer plantings, this was done last week. can these more mature trees tolerate practical limb cutting at a less than ideal time?

so as i interpret all of this helpful advice i am gathering that generally it is best to prune in early spring before dormancy breaks or new growth starts, correct?

I AM USING CAPS.. JUST TO DIFFERENTIATE YOUR WORDS FORM MINE..

i thought trimming the new top growth by about 1'-2' would help stimulate lateral growth and density.

==>>> NO IT WONT.. AND YOU WILL RUIN THE TREE ... LET THEM FIGURE IT ALL OUT ON THEIR OWN ... YOUR EXPECTATIONS ARE TOO HIGH ON RECENTLY TRANSPLANTED LARGE PLANTS ...

last week i cut the top 9"-12" of new growth in anticipation of the upcoming fall transplant

==>> BUDS WERE SET LATE LAST SPRING.. AND YOU CUT THEM ALL OFF ... WELL .. HOPEFULLY NOT ALL OF THEM ...

established/older appx 8"-10" diameter pine

PINE IS EXTREMELY WEAK WOODED.. AND IT SHOULD NOT BE SO CLOSE TO THE HOUSE THAT YOU HAVE TO PRUNE IT ... REMOVAL SHOULD BE CONSIDERED.. ESPECIALLY IF YOU ARE IN SNOW LOAD COUNTRY ...

----
thank god you found us.. ask BEFORE you prune.. next time

ken

Yeah I'd like to see a photo... but it sounds like that pine where you cut off a lot of the new growth may have really been messed up by what you did.

Sometimes I think they should issue pruning licenses like they do driver's licenses cuz one can do some seriously unpleasant damage just through innocent ignorance. Pruning is one of those subjects that cannot be properly taught online, even with a better youtube video :-) I really suggest one takes advantage of any hands-on pruning classes offered in their area - many retail garden centers/nurseries offer them for free at the appropriate time of year and sometimes even extension offices or botanical gardens will have "pruning clinics" that are extremely informative.

At the very least, get a good, thorough pruning book - my preference is the American Horticultural Society's Pruning and Training but there are other good ones. And as a last resort fallback, look up pruning requirements by specific plant online - pruning requirements, techniques and timing can vary hugely from plant to plant.

The large pine tree just needed to have some large overhanging branches cut off because they were starting to shade and hover some of my newly planted Arborvitaes . It was not near the house. Most of what I am planting is for screening

gw, the pruning you did on the larger pines, birches, etc. is the only legitimate pruning in your thread. And while not done at the optimum time, I expect they'll be alright. Others have already scolded you sufficiently for the other stuff!

+oM