Hi Tokyomafia,
It's very unlikely that seed will set on a double but the pollen will work just fine on singles. The extra petals on a double are the reproductive parts,stigma and filaments, flattened into petals. Sometimes there is a stigma but it cant seem to carry the pollen to the ovaries.
If you pollinate a single with a double you are likely to get viable seeds. About 25% of the offspring will show some form of doubling. Lora

This year I crossed pollen from a double to several varieties of single, all successful in forming pods. The first 2 pods split on the weekend and the seeds look great, with good embryo formation.
I can't seem to find a picture of my double (no label clearance from last year) on any site so cannot ID it but the pod parents include Dutch Belle, Picotee, Christmas and Exposure.
I could not find the true stamen on my double so only used it for the pollen. Seems to work.

K

Sometimes I find the stigma and pollinate it on doubles, but even before pollination, the seed pod looks like it would not be able to produce seeds. I don't know why I have this feeling. It just usually looks too thin and weak for reproduction. It seems like doubles turned the seed pod into something that holds the amount of petals in one flower. On the singles, the seed pod is already round, even before pollinating. Anyone had some observations about it?
How successful are you with pollinating doubles when you find a stigma?

I've had several doubles bloom for me, and have only found one that had the necessary stigma... it was a Lady Jane bloom... I pollinated it, but nothing happened. Perhaps the ovary couldn't support the pollen... or perhaps the stigma had a physical problem... I don't know.

Doubles are funny creatures... I would guess they're more man-made than anything through genetic manipulation... I'm not sure how they were created, but I do know that it's next to impossible to breed them!

Try slicing your spent double flowers all the way to where the seedpod should have formed. Most of them don't have any ovaries. :-(

My Jewel has brought about a successful seed pod-- that is one flower out of 8 that it produced on two scapes. Jewel, however, also has the tendency to be only semi-double, with one or more flowers nearly a single on one scape that also has two fully double-like flowers.

I have ALL of the seeds but haven't much of a desire to grow them for lack of space.

It would be very interesting to see what those seeds produce.

I have very little space, and so I'm only starting a dozen seeds of the varieties I want to grow. What survives out of those dozens will be my first flowers in a few years.

It's too bad the doubles don't have the necessary parts to reproduce... they're beautiful flowers, and it would be interesting to cross them.