How practical is a greenhouse in the Summer Months?

How practical is a greenhouse in the Summer? I am thinking on building a very small greenhouse but now that it is almost Spring I am just wondering what the upside would be. I am not planning on any special Plants just flowers and a small garden variety. I live in an Apartment Complex so it would be out on my Balcony.

Depends a lot on where you live. Here in central Texas it will burn up most everything during the summer unless you have a way to add shades that cut the sun way down.