I usually get one self-sown sprout each year since planting out my first one several years ago. Germination with any method I tried was very low as well. I didn't notice any marked difference in bloom times between my very early plant versus self-sown plants, so I think Caroline has offered a very valid point.
If I had a bunch of seed I'd happily toss them out in a more natural part of the gardens here and let them do what they will. They're great food plants for late season nectar-seekers.
