Hello, I have never before rooted in pure pumice, so I would like a little advice. I mainly want it for a Tulista pumila that has no roots. I think she's lost cause, I think too desiccated at this point. When should I add more water. I am using fine pumice. Where I live the next size up is I think too large, but I do have some. That is a dime in the picture. Which pumice is the better choice and when should I water?

Either kind should work but I would use the finer stuff. Make sure the pot is not huge compared to the size of the rosette, and that water reliably exits the bottom of the container. Given mild temps and strong light indoors, maybe water once a week for starters, twice a week if it's warm and dry. Pure pumice tends to hold less water and dry out faster than pumice with some organic stuff mixed in, so there is less danger of overwatering.