Plant shock refers to the stress a houseplant undergoes when there is a change in it's environment. Transplanting is one of the most common causes of shock. In the wild, plants stay in one place and grow roots deep and wide into the soil, so it's no surprise they do not like being moved by humans. Plant shock can cause leaf drop, wilting or even death. That's why it's important to only repot your plants when they need to be repotted.