Hi Aaron –
Fine-milled sphagnum wouldn’t have been my first choice, if for no other reason than that your pythons may track it all over the cage and make a complete mess for you. But if you get it set up in time in a container for the female(s) to pack it down, it will make a fine incubation medium. The key is to provide a good nesting spot as close to 90 degrees and 90 plus percent humidity as possible. If you are providing UTH heat, be careful to keep a close check on the temps. An infrared thermometer is great for this. If the female can’t find a perfect spot, she may well pick a hot spot (like under the newspaper, right on top of the heater) that will cook and kill the eggs.
Put a few inches of damp (not wet) substrate in a plastic container. If you can still squeeze water out of the sphagnum, it is too wet. Cut an entrance hole in the top or side of the container. Put the container where it will be around 89 degrees. The female should enter it and over time clear out a depression down to the bare plastic where she will eventually deposit her eggs. She doesn’t “sit” on the pile; she wraps her coils around it and supports all the eggs. During incubation, if you need to add more water to keep the humidity 90-100 percent, you moisten the substrate around the perimeter of the box, NOT directly on the eggs or female.
I’ve used maternal incubation less than half a dozen times over many years with both Burmese and ball pythons. It is a lot of fun to witness the natural process. My feeling is everyone should try it at least once. Of course, if you are into maximizing your breeding potential, it doesn’t make much sense. But it’s been working pretty well for millions of years for those pythons.
-Joan