Our club mix will be 50% lava and 50% pumice. We can get some fur bark for those of you who would like to add that also. This is a good mix to start with and can be altered if needed for different types of trees. You can add more lava or more pumice if you need a drier soil ( good for conifers ) Or you can add acadama clay soil if you need a wetter soil. Acadama soil can be purchased on line or at one of the many club shows around the bay area to be used for deciduous tress for example. If you need help to decide what mixture you would need for your trees bring your questions to the next meeting and we can help you with that.