Rice husks (hulls)

Rice husks (or hulls) are the hard protective layer of rice grains and are a by-product of rice production.

Due to their high lignin content, rice husks break down very slowly and therefore although as organic material can be composted the process is very slow. The husks are also water repellent, increase aeration, and cheap.

Disadvantages: When used alone, after a short period of time, the rice husks pack firmly together and prevents free passage of air and water. The very small size of the husks is also a problem.

I understand that s small number orchid growers do use rice husks in USA. I know rice husks well, I used them as bedding material in my horse stables, I also tried them once to pot orchids. I do not like them as a potting mix component and I do not recommended it.