Question
I have 8 six foot tall techny arborviitae planted at the back of my lot. They are planted about six feet apart in partial shade. I was wondering how wide do they get when they are mature? Looking on the internet I have seen any max width size of 4'-15'. How big will they actually get?
Thanks,
Jordan

Answer
Hello Jordan

Thank you for your question.

Arborvitae 'techny' grows to 15 feet at maturity (which could take up to 10 years).  At a planting distance of 6 feet apart they will become a very dense hedge indeed.  They can also get considerably taller than 8 feet, so you will have to keep them cut down to your desired height and also trimmed back to keep them neat and within bounds - once of twice a year should be OK.