Garden Grove Township, Decatur County, Iowa  Garden Grove Township is a township in Decatur County, Iowa, USA. As of the 2000 census, its population was 428. Garden Grove Township was created in 1850. Garden Grove Township covers an area of 35.73 square miles (92.55 square kilometers); of this, 0.04 square miles (0.11 square kilometers) or 0.12 percent is water. The streams of Mormon Pool and Weldon Creek run through this township. The township contains five cemeteries: Doze, Garden Grove, Metier, Morman and Winters.