In the late 1940s, Robert B. and Alice P. Withrow, working at Purdue University, developed a practical hydroponic method. His hydroponic system alternately flooded and drained a container containing gravel and plant roots. This provided the plants with the optimum amount of nutrient solution and air to facilitate fast and efficient growth.
During World War II, shipping fresh vegetables abroad was impractical and the remote islands where troops were stationed were not a place where they could be grown in the ground. Hydroponic technology was proven as a viable source of fresh vegetables during this time.
In 1945, the US Air Force built one of the first large hydroponic farms on Ascension Island in the South Atlantic, followed by additional hydroponic farms on the Pacific islands of Iwo Jima and Okinawa, using crushed volcanic rock as growing medium and, on Wake Island, western Hawaii, using gravel as the growing medium. These hydroponic farms helped fill the need for fresh vegetable supplies for the troops stationed in these areas.
During this time, large hydroponic facilities were established in Habbaniya, Iraq, and Bahrain on the Persian Gulf, to support troops stationed in those areas close to large oil reserves.
The US Army and Royal Air Force built hydroponic units at various military bases to help feed the troops. In 1952, the US Army Special Hydroponic Branch grew over 8,000,000 lbs. of fresh products for military demand. One of the largest hydroponic farms in the world was also established at this time in Chofu, Japan, consisting of 22 hectares.
Following the success of hydroponics in World War II, several large commercial hydroponic farms were built across the US, most of which were in Florida. However, due to poor construction and management, many of these farms were not successful. Despite the incredible potential of hydroponics, commercial hydroponics in the US lagged behind until hydroponic systems that were inexpensive to build and relatively easy to operate became commercially available.