If you notice that your jade plant leaves have fallen off, there could be two reasons why this happens. One reason is overwatering. Overly wet conditions cause the leaf blades to become weak and eventually break off. Another possible reason is too much fertilizer. Too much nitrogen causes the leaves to turn yellow and then wilt. To prevent this problem, make sure not to fertilize your jade plant every time you water it. Instead, only give them enough nutrients once per week through a diluted liquid fertilizer.