As I wrote I DID grow Japanese Morning Glories (I'm going back to the name for them I'm used to.) two or three years ago. I just didn't DO anything out of the ordinary to get them to grow. I don't think I even bothered to scarify the seeds (there were too many).
The only thing I COULD recommend doing that I didn't and wish I did doesn't appear to apply to you, because it looks like you are growing only one color of them. Since mine were "wild collected" and mixed, I WISH I had worked out a way to track each vine so as to be able to save the colors discretely, so that I would have control of which went where in the future.*
On one level, I agree, but on the other, sharing seed too vigorously is, at least for me, a double edged sword. In this seed saving world, seed that you have that someone else doesn't and wants is sort of a bargaining chip. For every person who believes in sharing freely, there is someone who guards their seeds like a dragon's hoard, and will only send you what you want if you can offer them something they want and don't have (I have mentioned the person on my other seed saving site who won't take modern cash for his seed and requires payment in silver). So that generally means that, per person, I usually get ONE chance per person to use any seed I might have to get something I want, and, as I don't HAVE many types, that means I have to make them count.
There is also the matter of amount. Because of the way I get most of my seed, and my poor growing situation, I tend not to have much of anything I might want to share to go around. So the amounts I can offer are quite meagre, and for some growers, that isn't compatible with the way they want to use the seed. Corn is a good example. When I send out corn kernels, I might send out ten or twenty, assuming that the person will grow them isolated for a year or two to up the numbers before playing around with it. But for a lot of people, that isn't how they want to work; they want to add it to their field grex IMMEDIATELY; and toss my ten or twenty seeds among their hundreds or thousands (where, generally, whatever trait they have is quickly swamped out my sheer numbers.) To solve this, there are some people who think that the answer is to simply get more of my seed, and ask (or even demand) that I turn over ALL of the seed I have, INCLUDING whatever I was keeping for my own use on the grounds that "I can grow it better than you can, so I have more right to it than you do." And, with my psychological makeup, I sometimes have a difficult time not thinking they are right, that, if it REALLY cared about saving these types, I would hand them over to someone more "worthy" as soon as I got them, and move from being a seed grower to simply a seed provider for others, taking all of the expense without asking for any reward or recompense.