When I want to make a new garden, I kill my Bermuda during the summer while it is actively growing. I spray it every week or two with a roundup type herbicide all summer long. The real trick is to stay on top of it after you plant your crop. If it ever gets re-established it's very difficult to eradicate. Don't use a weed guard. This just makes developing Bermuda all the more happy and hard to remove.
