I used to buy marigold seeds every year and also zinnia seeds as well as viola. The viola, if left alone to freeze, I have found, often come back. But as for the Zinnia and Marigold seeds, I let the flower get dry, pluck it off of the stem and put them on a paper towel until completely dry. Then I take them and open them and loosen the seeds into a paper bag. I place that in a container where nothing can get into it and the next year I plant those seeds or at least some. I went from four Zinnia plants my first year to 70 the next and I went from 4 Marigold plants to so many seeds I gave some away because I had so many I could have planted about 4 or 500 plants. Yes, it works and instead of paying 1.00 for those 10 or 12 little seeds, I have an unending supply. AND, they get prettier each year!