He also worked in the livestock, fertilizer, and chemical businesses, and contributed to foreign agricultural development projects in Eastern Europe, Central America, and the Caribbean.
[citation needed] Garst was appointed by the Carter administration to the Presidential Mission on Agricultural Development in Central America and the Caribbean.
In the 1990s, under the Clinton administration, Garst lead the agricultural portion of a development project in the Staritsky district of Moscow.
The project included the development of a dairy industry, egg and broiler houses, hog farms, packing plants, roads, and marketing systems.
Garst was a leader in Howard Dean's campaign in Iowa and was an active voice in the opposition to the 2003 invasion of Iraq.