Slag materials can also be used to grow orchids

Slag materials. Such as coal slag (be careful not to mistake it for coal ash), bagasse, cotton slag, shell slag, etc. Coal slag is very light; it can be crushed to a sand-like consistency, its powdered residue sifted out, and rinsed repeatedly with water to remove its fiery nature, then mixed with chaff material for use. It is convenient, money-saving, and gives good planting results, but coal slag is highly radioactive, so it should not be used much indoors. Bagasse must be rinsed repeatedly to remove its sugar content, then chopped up and composted for about a year before use. It can also be mixed with other growing media. Cotton slag is a byproduct of textile mills, and some of it still contains a small amount of cottonseed; it can be composted and then mixed with other growing media. Shell slag is a common sight by the seaside; it can be rinsed with water to remove its salt, then mixed into 2/10 burned soil or humus soil or pond mud. The characteristics of slag materials are that they are loose, airy, and relatively light, and they drain well. Their water retention capacity is also good. But slag materials themselves contain relatively little fertilizer, so attention should be paid to timely fertilizing.