Q: Tell me about bonsai tree soil. I’d like to mix my own.
A: Bonsai soil is very much different from potting soil. It has much less organic matter and a lot more rock or rock substitutes. Most bonsai enthusiasts mix their own soil, using expanded slate (PermaTill, Soil Perfector, etc), poultry grit and ground pine bark, plus other ingredients to make the soil drain faster or slower. Drainage is key; bonsai hobbyists use screens that vary in size from 1/16″ to 1/4″ to sort their particle sizes and eliminate dust and tiny pieces that would inhibit drainage. If you can’t find the components you need locally, go online to get them or look there to purchase ready-made soil.