Germantown, Wisconsin. In the fall of 1957, Otto, Jerry and Neal Karthauser purchased a greenhouse in Brown Deer, Wisconsin and named their business Karthhauser & Sons, Inc. Over 50 years later, Karthauser & Sons is a well-respected part of southeastern Wisconsin's growing industry. The business moved to its current location in 1985. In 2004, they developed a cut flower and growing products operation. With Otto's passing and Jerry's retirement, the current owners are Neal, his son Brian and their general manager Gregg Wilke.