PROBLEM TO BE SOLVED: To provide a technique which can warm a strawberry crown part at low cost in a simple structure without the need for piping, wiring and control means to adjust temperature.SOLUTION: A warming method of a strawberry crown part comprises the steps of: arranging a strawberry 3 planted in a planter 2 in a plastic greenhouse 8； laying a mat shaped warming body 30 in which a heat storage material is encapsulated in a flat bag along a side part of the strawberry crown part 3a； accumulating heat by warming the warming body 30 owing to an atmospheric temperature rise in the plastic greenhouse 8 during daytime； and warming the crown part 3a by the heat radiated from the warming body 30 during night when the atmospheric temperature is a solidification temperature of the heat storage material or less.
