Overwatering
Jade plants can drop leaves if they are getting watered too often. Be sure to only water the soil when it is 100% dry. Water slowly and deeply till water starts trickling out of the drainage hole, then remove any excess water captured in the saucer.
Underwatering
Rapidly falling jade leaves that are dry and shriveled could be a sign of underwatering. Water deeply until water trickles out of the drainage hole, and make sure you check the soil on a regular basis so the plant’s soil is never bone-dry for too long. Jade plants are thirstier in spring and summer, so expect the soil to dry out more often during those months.
Too Low of Light
Is your plant getting enough light? Jade plants love bright light! Ideally, they need sunlight for at least 4 hours a day when grown indoors. Smaller plants should be kept in bright, indirect light, but mature plants can tolerate more direct sunlight. Placement by a south- or west-facing window is ideal for growing jade plants indoors.
Pests
Check closely for pests! Mealybugs and scale insects could be causing your Jade to drop leaves. They make the leaves sticky and encourage the growth of mold, as well as deformed and falling leaves. If any signs of pests are discovered, quarantine the plant and treat it immediately.