Flower worked for Waco Air Transport Company where he learned to fly in a Waco glider. He later joined the Cessna Aircraft Company in 1940 as general sales manager. In 1953, he formed a partnership with Jack Galbraith selling aviation insurance. In 1958, Flower purchased Jack’s interest in the agency and the name was changed to Don Flower Associates. The company quickly became the largest general aviation insurance brokerage in the Unites States. Flower developed aviation insurance programs for many major aviation organizations, and was one of the first aviation insurers to be accepted by Lloyds of London. In his free time, Flower was an active pilot, making trips all across North and South America. Upon his death, his ashes were spread over Wichita Mid-Continent Airport in Wichita, Kansas from a Cessna 182.