Exemplary sap flow sensors are provided. A sap flow sensor includes a substrate having a main body and at least two arms spaced apart from one another. The at least two arms extend from the main body. The sap flow sensor further includes a sap flow gauge that is disposed on the substrate. The sap flow gauge is configured to monitor a flow rate of sap through a stem of a plant. The sap flow gauge includes a heating element coupled to an arm of the at least two arms. The sap flow gauge further includes a first temperature sensor and a second temperature sensor disposed on opposite sides of the heating element. The first temperature sensor and the second temperature sensor each coupled to a neighboring arm of the at least two arms.