Calcium (Ca) and Magnesium (Mg) are vital components to plant growth and cell strength. In some cases it may be necessary to supplement your regular feeding regime with Cal/Mag, or if using Coco Coir as a medium, you will need to buffer the Coco. Typically Coco Coir has an affinity for Calcium and Magnesium, and so it is possible that the Ca and Mg in your reguar nutrients are not delivered to the plant, but rather bonded to the Coco. By buffering the Coco prior to planting, you can minimise the amount of Ca and Mg lost to the Coco. Simply add the require amount of Cal/Mag to your water when swelling the Coco.