I just purchased two American boxwoods to be used around my central air condenser on my balcony. The balcony is covered, faces west and has concrete walls on both sides for privacy. We are on the 12th floor so we do get the wind gusts on those windy days. The summer sun is brutal here in July and Aug (if the temps are in the 90s) as we get direct sun starting at 2 am until sunset.

I purchased two big 20" containers (not clay) at Frank's. Any recommendations on potting soil, mulch, etc? I've read about root rot and other issues. I also purchased some Wilt Pruf to use this summer.

Anything else I should be aware of? Any tips? Do I need to drill a hole in my container for drainage?

Someone who grows in a zone more similiar to yours can better answer your more specific questions.

Unless you are one of those rare, mysterious people who is experienced at keeping plants alive in non-draining containers, you definitely want a drainage hole in your container.

With a west-facing balcony, you would get the brunt of the summer winds, but you would be somewhat spared of the winter winds that I get by facing NE, often churned up by the infamous Atlantic Ocean Nor'easters.

However I would still recommend you putting some sort of windscreen around your babies in winter. I have been finding that the smaller-leafed evergreens like azaleas and hollies, etc. (and this would definitely apply to boxwoods), seem to do worse with winter burn and dessication (even with the use of Wilt Pruf) than their larger-leafed cousins. The windscreen should be kept around the plants until almost March because I have found the worst damage seems to come in February, mainly because the days are getting longer and the sun + wind + dry air will negatively impact those little leaves, especially if the container soil is frozen (or close to it - ie., being frozen doesn't necessarily have a negative impact on the plant if it is hardy, but can impact if the soil starts going through a freeze/thaw cycle).

Many many boxwoods in the ground around here had some awful winter damage (usually seen in sections where one main branch and its offshoots would brown out). But keeping yours protected on the balcony (and trying to make sure that snow and ice don't sit for any length of time on them), should help.

And as luxum so succintly observed DO put drainage holes in those containers. Your plant won't live without them. ;-)