It is True. There are many different seed types, that will only germinate under certain conditions. If the proper conditions do not coalesce, these seeds can and will remain dormant for Great lengths of time. Some of these seed types were developed in partnership with Man. There are even seeds that may lie dormant for generations, of people, while land use is cycled between various types of crops. For instance, one type of plant flourishes while the land is utilized as forestry, while another only survives where there are open fields and food crops. 

It is entirely possible for you to sow flower seeds this year, and they may germinate years later, after you have long given up on them!

If you doubt it, just check it with your search engine. It is even more awesome to experience it first hand!