Have never reached the stage of harvesting seeds yet....I will this year though!! My were wintersown last year, but germination wasn't great for me...other's experiences may be different. They just started blooming few weeks ago :D
Seed pods/seed heads of any plant should be thoroughly mature (brown/dry) before harvesting.

Vera

Maggie - On my pink fernleaf, I wait until they turn black. If they happen to fall off the pod they are easy to spot on the ground because they are kind of shiny compared to the soil. Somewhere in my travels I've ready they do better if sown while fresh. It took me three or fours to finally get some to winter sow for me, I just wasn't having any luck. Now they babies have grown and I have them throughout the yard. I love them, they just bloom their heads off! I would try sowing them now and see if you have any success.

seeds need to be as fresh as possible. You can keep them moist with vermiculite or sand

hmmmm...... i don't know, i got mine from a trade from a trade, and i got them in hmmmmm.....when i first joined, then i ws them, do you know they have sprouted. unless your talking about the ones that you want to plant right now to grow now. LOL

I suspect even fresh seeds still need be mature seeds:D

Vera

I have collected seeds from my bleeding hearts and used them in trades, but I don't know the results. However, my bleeding hearts self-sow, and last fall I transplanted a few for a new bed. They have all grown this year and a couple have bloomed. They will bloom very quickly. The seeds will turn black when ripe. You may want to tie a paper bag around the pod while it's drying so you don't loose the seed. Since they self- sow, I presume they would WS quite well, but I would use the current year's seed.

They are mixed in with some snow on the mountain with large pine bark mulch under it all, so its really hard to find any pods that have fallen. I just barely touched one and it fell, but they are still green...I think I will try planting those seeds now, and keep my eye on the rest of the pods that are still firmly attached. The ones that came off were at the beginning of the stalk, so I think they mature from the bottom up. Hope I can get babies!
Thanks!
Maggie

I've tried the following before with mixed success...

wrap the seed pod with a bad (paper, like brown lunch bag -- not plastic) to catch the seeds when the ripen.

Or, wrap some panty hose around the seed pod loosely. The toe of some old panty hose works best. Then use a twist tie to attach to the stem. But not too tight :)

Then when the seed ripens carefully remove the bag and it should catch the seeds for you.

Good luck :)