Or do they?

According to the National Science Foundation, it’s all about the plant’s genetics or DNA. Because of the unique coding in their DNA, the environment around plants can trigger them to bloom. So for some flowers, this trigger can be set off by longer days of sunlight, more rain, and a warmer temperature, which happens during April in many places.

If you see a plant starting to bloom, you can take a picture of it every couple of days to track its progress. Here’s a video that did the same thing.