Corinne, I've used everything from promix to pure sand. I mostly use promix with extra sand and some turface. Fine seed I do not cover but I do cover the pot in saran wrap until the seeds sprout. larger seeds are either covered in the soil mix or sometimes I used fine grit. Budgie bird gravel works well as it allows light to reach the seeds and most alpines seem to need light to germinate.
I *do* bother with the sterilization process. The weather here is very unpredictible, and I have had problems with various kinds of damping off etc. in plants on my patio. Ordinarily I use a drench of physan when first wetting down the planting medium, regardless of origin. Boiling water would be a huge pain, but if it works better I am willing to try it.
Well - at my NARGS chapter meeting last year, Jim McClements described how he starts
ferns. He sterilizes his soil by thoroughly moisening the soil, places it in a baggy and then
places it in the microwave on high for 20min. This completely sterilizes it for the fern spores
and I would think would work for your purposes as well.
It might. I have done something similar (in the oven) for soilless mix for my rose cuttings. I am starting several thousand plants just now, and I would be microwaving constantly between now and next march if I did that. I think I will take my chances with my current method using physan drench.
Have you tried hydrogen peroxide? I've seen folks swear by it on the seed starting thread.
I tried it last year but haven't had enough trouble with damping off to say much one way or
the other about it.
I think promix is comparable to the soilless mixes we have available here. I always add chicken grit and/or vermiculite for anything that will be sitting outdoors, and vermiculite to anything under lights indoors. I have ocassionally used peroxide on my rose cuttings, but with mixed results. Physan works better for me, esp. in the winter.