Hi Lissa, it has been a while since you posted your question. This is the first time I saw it. I hope you’re getting enough satisfying results to keep you interested in continuing.
I know something about one species of Cleome. I don’t know if it is true for all species and you didn’t say what species you had collected seeds from..
Cleome serulata is a plant that is native to the western USA. It’s common name in these parts is Rocky Mountain Beeplant.
It’s a beautiful plant, knee to shoulder high, covers itself in mauve colored flowers. It had apical clusters of flowers and they are indeterminate. The plant will keep blooming as long as conditions are suitable. I have been told it is a “pot herb” and that the black color on Ana’azazi pottery was derived from this plant.
To break dormancy on the seeds, the easiest way is to toss the seeds out in the fall in the place you want them to grow next year. It’s very common for people to put seeds in the refrigerator to break dormancy. With Cleome serrulata, the seeds need oscillating temperatures, which is easiest to provide by having them outdoors. I have never tried putting a container of seeds outdoors for the winter though that may work.
I seed really heavily because if I get poor germination I will still get some success.
Beeplant is a prolific reseeder. Generally will return year after year. At that point, I collect seeds to share and to get them started in new locations.
Lots of insects like it.
I have posted photos of seedlings, but they’re pretty small.