Does anyone think its possible to grow a cocoa tree in USDA Zone 7b from the 2012 map ? I was going to put it in a movable green house I designed with a heater and humidifier during the winter months and it will keep the plant at about 75 degrees and 60 percent humidity. any advice or comments will be appreciated thank you.

I've never tried to grow one although I have seen a lot in very tropical places. If you have done your researce and can mimic the growing conditions of the tropics they are native to, I would say go for it.

I think your biggest challenge will be accommodating it when it grow to 25 feet.

Theobroma cacao comes from Central America and is listed for Zones 11-12. With your greenhouse to protect it from cold, it has a chance, but the shorter winter days in your zone may affect it. Interesting challenge!