system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do seeds "know" to start sprouting?

I ask this because I recently bought some flower seeds at a gardening place. The seeds came in a small paper pouch and were all dried up. I followed the instructions on the pouch and the little tiny leaves have just broken through the dirt. 
The ones in the pouch still are just chilling out. 

How then, did the seeds "know" that it's ok to sprout? 

I thought maybe it's the presence of water. But then how would it stop from sprouting in a lake where it will likely not have the proper things to grow?
gpt
Most seeds have to go through a freezing process called stratification befote they will germinate. Stratification prevents the seeds from germinating as soon as they are in the correct conditions (moisture and darkness) but would not have enough time to grow large enough to survive winter. So once the seeds freeze and then thaw, the presence of moisture and darkness allows the seed to germinate. This allows them to sprout at the beginning of a growth season and maximize growth to survive the winter.

Edit: seeds do not always grow in the correct place (as to your question) and that is why seeds are usually distributed in large amounts by the shrub or tree to maximize the chance of a seed successfully growing to full size.