Recently, the decline in plant species, loss of crop yields, and reduced efficacy of herbal medicines due to environmental issues and biotic stresses have garnered significant attention. Developing smart devices for plant health monitoring is essential for early intervention, timely adjustment of the growing environment to combat environmental and pest stresses, and to promote robust plant growth, biodiversity, ecological balance, and sustainable agriculture. Flexible wearable sensors with the advantages of superior shape adaptation, excellent biocompatibility, and high integration have emerged as one of the most promising avenues for plant health monitoring. Here, recent advances in flexible wearable sensors based on monitoring different types of plant signals are summarized. The discussion focuses on the constituent materials, fabrication methods, and sensing mechanisms of each type of wearable sensor. In addition, the challenges and potential strategies are summarized for plant sensing development, including energy supply, materials and preparation, signal transmission, and data analysis.