Rice/Paddy husks are the hard protecting coverings of grains of rice. In addition to protecting rice during the growing season, rice hulls can be put to use as building material, fertilizer, insulation material,birds pad,puja,yaganas or fuel. Rice/Paddy husks/ hulls can be composted, but their high lignin content can make this a slow process. Sometimes earthworms are used to accelerate the process. Using vermicomposting techniques, hulls can be converted to fertilizer in about four months. Rice/Paddy hulls that are parboiled (PBH) are used as a substrate or medium for gardening, including certain hydro cultures. The hulls decay over time. Rice hulls allow drainage,[ and retain less water than grow stones It has been shown that rice hulls do not affect plant growth regulation. Paddy husks are used in Cactus and Succulent potting mix."