I use red lava rock or Aliflor (a type of expanded clay balls). A huge bag of red lava rock costs around $6 here and lasted about two to three years. The Aliflor was a little more expensive per amount but it works better for those orchids that like a little more moisture. I paid about $5 for a box of this. The best thing about both of these is that I won't need to replace my medium every year as it doesn't decay. The second best thing is that because it doesn't decay, I never need to worry about the medium in the middle becoming compacted and holding too much water.
Hybrid Mode
