These lovely Calendula are such a surprise! They sprouted within a day! Last year they took weeks on end, and repeated attempts and conditions. They either molded, or withered shortly after sprouting, or just plain rotted. I believe the term for it is “damping off “. It took months to get anywhere with them. So, when I planted these seeds from my own harvest, I was leery of what trials awaited me, and I wondered if the bees got to pollinate well. But they did! 90% sprouted so far, in this first batch at least, and I’m thrilled! So far… As the mother plants were not that strong and struggled, it is rather amazing to see so much robust health come to her offspring. I made sure to keep the earth as neutral as possible, and pasteurized the earth this time by baking it at 150 degrees-the lowest my oven will go-for about half an hour to 45 minutes, to make sure to kill off any stronger pathogens, bacteria, kill weed seeds and fungi. I imagine the sun would naturally do this pasteurization process if the earth were outdoors. Whereas, sterilizing kills everything, pasteurizing retains some of the good organisms.
There seems to be differing temperatures to bake at, and some people recommend covering the earth, and preheating the oven to 200 before lowering. After seeing a graph, which I can’t find again to re-post, on what gets killed at certain temperatures, I settle for 150 degrees.
Here are some links on pasteurization:

mother earth news-compost
pasteurize compost