OSA★28 Plant Available Silicon (as monosilicic acid) strengthens cell walls, increases nutrient uptake, and helps plants handle all kinds of stresses. Other silicates are not bioavailable and take time+microbes to become plant available. This makes OSA★28 the fastest option for delivering silicon directly into the plant cell walls! Silicon also has a synergy with calcium in building better plant structure. Many growers see increased calcium response when feeding with OSA★28.