One possible reason your Dieffenbachia is falling over is that it is not getting enough light.

Why is My Dieffenbachia Falling Over? (Causes and Solutions)

If your Dieffenbachia is falling over, it’s likely due to one of several reasons. The most common cause is that the plant is top-heavy and needs to be staked. Other causes can include root rot, insufficient light, or too much water. Luckily, there are solutions for all of these problems. Read on to learn more about why your Dieffenbachia is falling over and what you can do to fix it.