I don't have flowers but I do keep my ivy, I think German ivy, you just break a piece off and stick it in the soil and it roots itself. I have another ivy that you root in water. I also kept another plant that is like a succulent that you break off and put in the soil to root. I don't remember the name, but friends of ours lived in Texas and said it is a weed down there because it spreads so easily.
I think moss roses do well started from seed and I have started morning glory, nassturom (spelling wrong) and holly hocks.