I'm new to the concept, but am gathering seed of flowers I think will self-sow freely on a sunny hillside (columbine, poppies, foxglove). Plan to mix them all up together and strew them this fall. We'll see what happens. I plan to also add in all the 'old' seed I have here and there. Can't hurt. The ultimate goal is for a wildflower meadow. I'll have to hand snip the blackberries, thistle, and burrs - but hopefully that won't be too much of a chore. We're also getting a small amount of tansy ragwort that must be stopped in its tracks.
I've been saving all season as the seed becomes ready. Man the moss rose is going crazy right now & I'm going to have to spend my next day off collecting those tiny tiny seeds. I can't wait until next year when I (hopefully) don't have to buy that or the zinnia or the snapdragon or the petunia. Fingers crossed!
We've had an extremely weird summer in North Carolina; started out very hot and dry, very quickly, and then it rained during 6 weeks of T-storms when an inch or more would fall in less than half an hour, so many of my flowers were either knocked off or rotted. Now that the weather pattern has shifted again, I've been able to harvest a mess of coneflower seed- orange coneflowers. My snap dragons I allowed to reseed and surprise! A new plant shot up just this week!
However, I've been saving seeds for a couple of years, now.
Saving pepper seeds. I have found that by keeping them in containers I can make sure they don't cross by moving them when the flowers start to open. Do to family issues out of state my garden and plants have been neglected. But I have 2' plants growing in 3" pots. By watering with fertilizer the leaves are still green and they are setting fruit. Some are in my sunny laundry room and some are on my covered deck, these are all doing better then the ones in the ground in the garden.
I also chose "other" 'cause, while I haven't been saving since Spring, I did start earlier this summer. I'm fortunate to work at a nursery/garden center, so not only have I been collecting at home, but I've been "deadheading with a purpose" here and there at work as well. That reminds me, GOTTA remember to take some extra baggies with me to work today! =)
When the blossoms begin to fade, I place little muslin bags over, so I collect the seeds.
Mostly poppies so far, including blue poppy seeds which are hard to come by when fresh and viable.
Leopard's bane, lupins too.
The bags I get at Buck or Two stores-----they are meant for wedding candy or party favours.
I always have a few seeds here and there saved but this year I pretty much knew I had too many and just decided to save the seeds from late Summer/early fall blooms like my daturas so I don't have so many to contend with, since we are in the process of several large changes, in case I won't have time for trades this next year.