Orchiata bark compost perfect for all types of Orchid Plants, recommended by top growers around the world, Retains Structure , Re wets easily, use straight from the bag no need for sterilization, Dolomite addition creates a stable PH adjusted substrate, Produced from sustainable renewable, man-made forests. This orchid compost has been specifically designed for orchids, and both hobbyists and commercial orchid nurseries have proven its ability to produce superior growth on orchid plants. Orchid Compost Size guide Power 9-12mm, orchid bark Medium Grade suits both young and more mature orchids, a good size for second potting.