Is there anything wrong with NOT trimming arborvitae? I have a lot of them on my property line and it is costly/laborsome to trim. I was planning on doing so every few years but am now toying with the idea of just 'letting them go'. Any issue with that? How big in diameter will they get? Would they be heartier or weaker with snowfall? I would think the taller they are the stronger they are. They are ~ 11 feet now. Not as 'grown in' together as I would like but that should occur without topping them right? O r am I mistaken?

Arborvitae exist in nature without any pruning and live long lives. They are large growing upright evergreens. As long as your have room to allow them to reach maturity, there is no compelling reason to prune them. Depending on the species/cultivar, some may open up with age or be more prone to snow load damage. "topping' them in no way promotes them to be thicker evergreens. Depending on species, they could be 10-12 feet wide at the base, and 25-40 feet tall

Richard,

Thanks so much for the reply. Probably not enough info but all I know is they are Dark American arborvitae. The only compelling reason I would have to prune I suppose is if they grow to wide at the base as I put up a polynet deer fence in the off-season (OCt-Apr) to try to keep deer away from the trees. If they are too wide, branches would press against the fence, eventually compromising it. If I wanted to just trim to the height of the fence, would the trees look funny as they grow? Also, if I were to trim the trees myself is there a good resource to know specifically how to do so without damaging the trees? And what equipment to use? I have heard a lot of opinions but frankly am unsure .

Tools first - a pair of good bypass pruners, a sturdy and sound stepladder if needed

Pruning - Where you prune is where the new growth will resume. While you can prune to a given height, regrowth will occur from several inchs below your cut and in a short time be back to the previous height. Attempt to find a smaller twig/branch or bud to prune to and not pruned off leaving a stub. Once you begin pruning, you will likely find yourself pruning every year attempting to maintain growth. For example if the Arbs are naturally maturing at 12-15 feet and pruned down to 6-8 feet, you will always be pruning in an attempt to manage heights. Pruning away a few bits of the side branches to allow your deer fence to work properly is not like attempts to limit top growth.