In 1953, she married John Humphrey Cooke at Waimate, and the couple went on to have four children.[2] In the late 1950s, they purchased the 8,000-acre (3,200 ha) Big Ben Station near the Rakaia Gorge, where they farmed sheep and cattle.[2] In 1991, Janet and John Cooke retired to Akaroa, before moving to Greenpark near Lincoln, and then Wellington, where John Cooke died in 2013.[2] Janet Cooke died in Wellington on 17 May 2021.[3]