Hopskip, The answer to your question is yes. But, there are many other alternatives to arborvitae as far as screening is concerned. They grow very slowly. So, you won't have to worry about them outgrowing a large pot for many years. They hate cold winter winds. It is their enemy, so if you could move the pots in the winter to a more sheltered location such as behind a wall somehow, they wouldn't get as wind burned. They have to be watered, even in the winter if you aren't getting much rain or snow. At least once a week when it is hot out, even twice a week in a pot. on concrete. They will be hot. Concrete is very hard on plants. It holds the heat and reflects the sun onto the plant. If I were you, I would try a heat loving plant instead on concrete. Do you need privacy in the winter also? How often are you outside when it is real cold? Just a few suggestions for heat lovers in case you want spring,summer and fall privacy are Roses, a nice big variety. Grows tall, plenty of foliage, easy to grow in a pot on concrete, (I have one for privacy now on concrete) it actually loves the heat. Crepe Myrtle- believe it or not,I don't know what state you are in, but you could try a crepe myrtle on concrete if you put burlap over it in the winter. Rose of Sharon, grows fast, not expensive, loves heat, just water it alot, grows in all conditions. Nice flowers. Ornamental grasses- cut them back in March, they grow real fast, privacy all summer and winter long til next March when you have to cut them again. The older they are, the faster they come back, especially in a pot. You could put down something on top of the concrete to block the reflection of the sun like some cheap bamboo blinds (would look nice too) or bamboo rug and then you could grow anything in a pot there for privacy. Arborvitaes belong in the ground. (that's just my opinion) In any case, good luck. Others will probably have better suggestions.

Thanks Al. I bought 270 of them as that was the minimum order from the wholesaler and I would like to use most of them for privacy trees around my yard. They are actually called American Pillar Arborvitae, they are a patented version of the green emerald but grow much quicker and much taller, officially 3 feet a year reaching 25 feet. They were a third of the price when buying wholesale, about $4 a piece, but that is why I need to replant them because they come in these tiny containers. What would you recommend me repotting them in? I can't use your gritty mix like I am using for my citrons because of the price, and also cutting up the pine bark is way too time consuming for that many trees. I figured that for only 4 months I can go with regular miracle grow potting mix. I was also thinking of mixing in some perlite to the miracle grow potting mix. I also liked the idea of the miracle grow because it has fertilizer and I won't have to fertilize.

I am embarassed as I have yet to meet an arborviate that I did not really, really like, but I was not aware of the Fastigiata/Pyramidalis. I dont think I have ever seen one for sale in Columbus, Ohio or I would have bought some. Having seen pics, it is #1 on my list, hopefully they can grow around here. I saw what I thought were smaragd 3-4 years ago when I was even more of a conifer newb. I was in a moving car and they were a far enough away that they definitely could have been pyramidalis, especially if they were pruned more cylindrical to better match smaragd shape. Google image showed quite a few like this. Thus you are most likely correct gg, especially since I didnt even know of this tree at the time. Thanks for all the great info and suggestions you provide gg, GR8 stuff!

You are not likely to be successful with any tree grown in a container long term in CT......without some sort of winter protection available. Even quite large containers can freeze solid in a cold winter and the roots are the most vulnerable portion of the plant with respect to cold damage. And because of their exposure, containerized plants are subject to much colder temps than the same plant in the ground. btw, growing trees long term in a container requires quite a lot more time and attention than one might imagine. Watering needs accelerate, you have to fertilize regularly and the potting soil will need to be refreshed periodically as will the need to root prune. That can be a lot of work for more than just a couple of trees and the larger they are, the harder it becomes. btw, trees in containers do have a limited growth......both mature size and rate of growth will be substantially reduced compared to the same tree in the ground. Very similar to bonsai but on a larger scale. A Green Giant grown in a container will never reach 50'.........more than 15-20' would be impressive. Bamboo could be a reasonable solution if you use a clumping bamboo and plant in the ground. Relatively fast growth, evergreen, significant height and if a clumper, no danger from unwanted/uncontrolled spread and no need for containment. Check out the Fargesia species. Also very cold tolerant.