Susan Sowerby is Martha and Dickon's mother. Because Martha refers to her only as "mother" when she speaks about her to Mary, Mary also uses "mother" to talk about Mrs. Sowerby until she meets her months later. Martha admires her mother, as she's an exceptional baker and a loving parent to her twelve children. This admiration is shared; both Mrs. Medlock and Colin's nurse discuss how skilled Mrs. Sowerby is at raising children. They specifically latch onto her insistence that a girl like Mary should be allowed to run outside and develop independently, rather than be put in the care of a nurse or governess. She even writes to Mr. Craven saying just this, and he takes her advice seriously. In her conversations with Dickon, Mrs. Sowerby shows herself to be kind, curious, and respectful of the private world that Dickon inhabits. She takes a keen interest in Colin and Mary's development and begins sending along baked goods and fresh milk. This allows Colin and Mary to pretend they're not hungry for their meals at the manor, thereby throwing their caregivers off the scent of Colin’s dramatically improving health. Eventually, Colin and Mary invite Mrs. Sowerby to the secret garden, where she shows them how a mother would care for them by hugging them, listening with interest to what they have to say, and feeding them nourishing foods. She's taken with Colin's understanding of Magic and she agrees that regardless of what a person calls it, it represents a belief in the divine and is therefore good. Following this, she writes to Mr. Craven and encourages him to come home.