GREENHOUSE in Texas?

[paysensmom]

I want to have a year round garden. We will be moving to San Antonio in June. I thought since the climate was pretty mild in the winter, I could have a greenhouse garden in the winter!! Do you think a portable greenhouse would be enough to just place over my summer garden?
Thanks!

[momto2nenas]

I don't know much about greenhouses but I garden and live in San Antonio :)

It does freeze here, I was actually shocked at how cold it can get (we moved here last June) down in the 30s a few times.