Cinder, also called scoria, is a highly porous volcanic rock often used for its appearance in xeriscape, but it is also prized as a soil amendment in permaculture due to its paramagnetic properties. Cinder is used to increase soil tilth and water retention, while also created spaces for excess drainage and increased oxygen flow through the root zone. Cinder is shown to increase micro-nutrient availability in soils and can help prevent some pests when used as a mulch for succulents and desert plants. Due to its sharp texture, cinder is not recommended as the primary medium in succulent or bonsai soils as it can damage roots, but it can be used lightly in the soil or as mulch for a uniform and beautiful look.
Mix as much as 10% scoria to compacted soils or potting mixes for increased aeration and drainage.
Soilutions Red Cinder is screened to 3/8 inch and smaller and will contain lava sand. Lava sand is highly beneficial in soils as it is mineral rich and increases water holding capacity, but for succulent/native plant mulch we recommend rinsing cinder to minimize lava sand.