After her husband's death in 1967, Illa Martin saw that economic continuation of the Sequoia Farm was impossible and so sold the site in late 1969 with buildings at the College of Education Rhineland (now the University of Cologne).
Efter hendes mands død i 1967 indså Illa Martin at at det økonomisk ikke var muligt at fortsætte med at drive Sequoiafarm  og solgte derfor ejendommen i slutningen af 1969 med bygninger ved College of Education Rheinland (nu University of Cologne).