Della is a twelve-year-old girl who lives on her family's watermelon farm in a small Southern town. Deeply observant and loving, she adores watermelons and spending time with her best friend. When her mother's schizophrenia begins to worsen, Della takes it upon herself to find a magical cure, feeling personally responsible for her mother's illness.

Mama is Della's mother, described as pretty with straw-colored hair, a love for stories, and a habit of singing to her daughters. She struggles with schizophrenia, which makes her fixate on germs and harbor irrational fears for her children's safety. Despite her illness, she is deeply loved by her family, who try to manage her good and bad days.

Daddy is a hardworking farmer trying to transition his family's inherited farm to organic practices during a severe drought. He is usually calm and dedicated to his family, fighting against the stigma of mental illness by treating his wife with dignity. However, the combined pressure of a failing crop and his wife's declining mental state begins to heavily tax his patience.

Arden is Della's homeschooled best friend, living in a lively, stable home next door. She is cheerful, loyal, and frequently shares humorous stories about her siblings. While her stable family life sometimes makes Della envious, Arden provides a safe haven and unwavering friendship during difficult times.

Mylie is Della's eighteen-month-old baby sister. She is a mischievous and active toddler who is heavily impacted by the sweltering heat and the emotional turbulence in her home. Her basic needs often force the rest of the family to confront the reality of her mother's illness.

Miss Tabitha, known around town as the Bee Lady, is a local beekeeper whose honey is rumored to have magical healing properties. She tends her hives barefoot and without protective gear. Kind and perceptive, she recognizes when others in the community need emotional support.

Miss Lorena is a kind family friend who is studying for her college degree after the death of her husband. She is perceptive and compassionate, turning to books during difficult times. She serves as a maternal figure in the community, ready to support families going through challenging periods.

Thomas is a sixteen- or seventeen-year-old newcomer to town who takes a job helping on the Kelly farm. He is studying to improve his SAT scores for college scholarships but struggles with math. He treats Della with mature respect, making her feel capable and valued.

Dr. DuBose is the medical professional in charge of Mama's psychiatric care. He understands the triggers for her illness and emphasizes the importance of rest and medication, though he faces resistance from his patient.

Arden's mom is a warm, attentive parent who homeschools her children and maintains a lively, functional household. Her maternal affection and stable home environment serve as a painful contrast to the struggles in the Kelly household.

Arden's dad is a supportive neighbor who helps out around the farm stand and offers a listening ear to the adults in the community.

Grandma is Daddy's mother, who moved closer to the city after her husband suffered a stroke. She maintains a close connection with her family, calling every Sunday and sharing recipes to maintain a sense of routine.

Grandpa is Daddy's father, who previously ran the Kelly farm before suffering a stroke and moving to the city with his wife. He is a quiet but respected presence in the family's history.

Mr. Anton owns the local gas station in town. He brings his nephew to live with him and helps supply the local farmers with necessary equipment parts.