Plants that thrive in partial sun need a full day of light, but not a full day of direct sunlight. In outdoor gardens, these plants can tolerate 4-5 hours of direct sunlight and they should receive indirect sunlight for the balance of the day. When grown indoors, partial sun plants thrive on an east-or-west-facing window that gets a full day of light including direct sunlight for 4-5 hours and the balance of the day in direct light but not hot sun. Plants that need partial sun should be kept out of the hot noon sunlight. In a light garden, partial sun plants need 12-15 hours of light depending on the season.