Orchid bark is simply regular pine bark that has been screened several times to ensure that the majority of the wood and cambium has been removed. What is cambium? It is the stuff that makes the bark stick to the wood. Why should the wood and cambium be removed? They degrade faster than the bark and as such will cause the bark to degrade faster. You want your orchid bark to remain open and not degrade for as long as possible. Orchid bark is suitable for orchids that like a good, open and well-drained mix. We have the bark available in three grades, #2 (approx 3-8mm), #3 (approx 8-20mm) and #4 (approx 20-25mm). All three grades are available in a 50 litre bag and repackaged into a smaller 5 litre bag. The 5 litre bag is suitable for those people with only a small collection of plants whereas the 50 litre bag suits those with larger collections.