The prime theme in The Tulip Garden is devotion. Although Arlen has been left shattered by his wife's decision to leave him and their two children he builds his life around the hope that one day life will return to normal. Devoted to Jennifer, his wife, and his children Reagan and Marylin, Arlen makes the ultimate sacrifice to bring his family back together again.

A second theme used in the book is based around the notion of 'the apple doesn't fall far form the tree'. Although life has been a constant struggle for Marylin throughout her childhood, when she becomes a woman with her own life to lead she begins to follow a course of actions that will see her let history repeat itself. There are those in the world who believe a person's life is mapped out at birth and no matter what, the child will emulate the parent. There is also an opposing view that behavioral modification and self-examination can lead the child of a degenerate to be a moral stalwart.