Cal-Mag is a supplement containing essential macro nutrients, magnesium and calcium, which are vital for plant growth. While these nutrients are needed in smaller quantities compared to NPK, they are still crucial for plant development, especially for growers in soft water areas, those using reverse osmosis filtration, or working with coco-based mediums. Calcium plays a primary role in providing strength to plant cell walls, similar to its role in providing strength to human bones. On the other hand, magnesium is a fundamental component of chlorophyll and is essential for photosynthesis. In addition to these secondary nutrients, Cal-Mag also includes a blend of trace micro elements to address any potential deficiencies.

In essence, Cal-Mag is a source of secondary macro nutrients – magnesium and calcium – crucial for plant health. It's particularly important for growers in soft water areas or those using reverse osmosis filtration, as water with low mineral content and insufficient magnesium and calcium can lead to deficiencies in plant health and nutrition.

Ultimately, the use of Cal-Mag is essential for ensuring plants receive a regular supply of magnesium and calcium for optimal healthy growth, similar to the way humans require these minerals for their well-being.