Any spray on Plant fungicide will do. Powder is too gloppy and cinnamon doesn't seem to work for this application.
The fungicide is a preventative measure. I don't always manage to provide the best growing conditions and I hate to wait 2 or 3 weeks for seeds to germinate just to have them damp off.
Now I have to go feel the top of my refrigerator. Art is right - you don't need bottom heat. My vegetable seeds are toughing it out on their own on the floor of the greenhouse. But I am trying to start some Indigo and Shiso also. They are on a heat mat with a dome. Damp off problems are a given with that combination.
Daisy