It became apparent about two years ago that there are some natural ceropegia pollinators here in Staten Island. I began placing plants that bloomed at the same time near each other in hopes that they would cross, simply because they were in close (touching in some cases) proximity. I have tried to pollinate the flowers myself but the polonia and the place where they are supposed to go are so small that that I wound up damaging the flowers rather than crossing them. When seed pods form, I collect, lable as to seed parent, and plant seeds from individual pods separately. It has been very interesting to see the differences in the seedlings even from within the same pod.
This is a picture of seedlings from one seed pod taken from C. debilis ssp. linearis showing a wide variety of leaf shape and coloring. There are also greater and lesser amounts of marbelling. As these plants have grown I have also noticed that some are climbers and others are trailers.
I start all of my ceropegia seeds in a seed starting mix. I put the sterile soil-less mix into closable container. Small amounts of seeds, up to twenty, will go into a yogurt cup that seals with a clear plastic top (Dannon), larger numbers of seeds will be put into deli type containers. I punch holes into the bottoms of both types of containers with a hot ice pick before filling them with soil. The soil is doused with water and drained before I spread the seeds. The seeds are sprinkled on the surface of the wet soil and then a quarter inch (.5 cm) layer of traction grit (do NOT use sand) is sprinkled on top of the seeds. The container is sealed and put in a warm place under lights. Germination of fresh seeds takes from 5 to 9 days; although I have had a 'second wave' of germinations after about 3 weeks, in a pot where the first seeds germinated in 10 days (Hybrida hort.).
When the seedlings are about a half inch tall and begin to show the first true leaves I uncover the container and allow the plants to grow to about 5 to 7 inches depending on the species before transplanting. I would recommend that even in transplanting, that you simply lift the mass of seedlings out of the starting container and place it in a larger pot. I have lost too many seedlings, especially tuberous types, by planting them too low or too soon. For the tuberous types, I am waiting until they get their gray skin before before transplanting into individual cells or pots.