bfou, that is not the case; Johnson's Blue will do fine by way of seeding.
You might ask around at seed houses about this border plant that doesn't like to be shoved around or put where other plants will shade it. It can take partial shade to sun well, flowering lasts June to August.

The plant does not, evidently, do well by division. Instead cuttings are recommended for better results

The "sanguineum" is a familiar pinky red variety (also known as Bloody Cranesbill) that naturalizes well and has the same flowering period as J.B.

thanks.

Jeannie7, I have no idea where you got that information from but it is incorrect. 'Johnson's Blue' IS a sterile hybrid and every valid hardy geranium resource will confirm that. That's one of the reasons it enjoys such a long bloom season. There are a lot of JB look-alikes on the market which do set viable seed but not the true 'Johnson's Blue'. And it propagates easily by division - the plant is semi-rhizomatous and spreads well.

bfou, your seeds could be anything and certainly worth planting, but if they do in fact germinate and produce flowers, they will NOT be 'Johnson's Blue'.

Here is a link that might be useful: JB look-alikes and other G. pratense hybrids

maybe a good candidate for one of my first winter sowing projects? i'll just see what comes up.