Michigan State University has had a weed seed germination experiment going on since 1879. Bottles with a mix of weed seeds were buried and are dug up on a regular basis to see which seeds will germinate. The latest bottle produced only Moth Mullein, Verbascum blattaria, from 120 year old seed. http://newsbulletin.msu.edu/july27/beal.html Five of the original 20 bottles remain buried, and the next one to be dug up and tested will be in 2020. Diane Whitehead