Reply To: For Autopot, when using Sohum Living Soils, is perlite used. What ratio, if so? September 8, 2019 at 5:33 pm #239 JoshKeymaster There is no need to add additional perlite, Sohum soil also needs to be used in a pot with a minimum size of 20ltr or the volume will not be great enough to supply the food for the duration of the plants life.