You have to install some type of EXHAUST fan. Simply moving the hot air won't help, and may in fact dry out the plants worse.
You can go the cheap route and do a 'duct-booster' fan from home depot, or you can go with a high-cfm blower that will really move some serious air. FYI if you intend to run a carbon filter at some point, a duct fan doesn't work, you'll need the blower.

Palerider, you KNOW you don't have to quote the entire post and then post some snide remark, right?