Hi, You want the flowers to die completely and get brown. If you pick the dead flower too soon, the seeds will not be ripe. Hopefully, you get lots of blooms, so if you check on one and you picked it too soon, you'll have lots more to harvest seeds from. The seeds are big chippy things, so at least they are easy to identify. The link below has a pic. Remy |
Here is a link that might be useful: Dahlia Seed Photo