Day/night temperature differential (DIF) refers to the difference in temperature between daytime and nighttime. In horticulture, the DIF is an important factor in regulating plant growth, particularly in greenhouses. A positive DIF (warmer days and cooler nights) promotes stem elongation, while a negative DIF (cooler days and warmer nights) can help control excessive growth and improve plant compactness. Managing DIF can lead to better control of plant height and development.