GreenPlanet Nutrients Pro Cal Supplement

Pro Cal is formulated for use across all stages of growth — vegetative and flowering. Calcium and magnesium are required continuously throughout the plant's life cycle, as both elements are involved in fundamental processes including cell wall construction, chlorophyll synthesis, and nutrient translocation that never stop being relevant.

Apply at 1.25 ml/L (4.5 ml/Gal) with every feeding as needed, adjusting based on observed plant response and the Ca and Mg contribution already present in your base nutrient formula.

Calcium deficiency typically presents as distorted or necrotic new growth — curled leaf tips, brown edges on emerging leaves, and stunted shoot development. Because calcium is immobile in the plant, symptoms appear at new growth sites first rather than on older leaves. Magnesium deficiency shows up as interveinal chlorosis — yellowing between the veins on older leaves — as the plant pulls magnesium from mature tissue to feed new growth.

Growers using RO water, soft water, or coco coir as a medium are at the highest risk of Ca and Mg deficiency and typically benefit from consistent Pro Cal supplementation throughout the full growth cycle.

Calcium and magnesium are classified as immobile or semi-mobile nutrients — meaning once they are deposited in plant tissue, they cannot be efficiently redistributed to new growth sites the way mobile nutrients like nitrogen can. The plant cannot pull calcium from an older leaf and send it to a developing shoot tip, which is why deficiency symptoms consistently appear at new growth even when older tissue looks healthy.

Pro Cal addresses this by supplying both elements in readily available, soluble forms that the plant can absorb and transport to active growth sites before they're locked into existing tissue — ensuring new growth always has access to adequate calcium and magnesium supply.

Pro Cal's 2% nitrate nitrogen serves a functional role beyond basic nutrition — nitrate is one of the most readily absorbed forms of nitrogen and supports the active uptake mechanisms that bring calcium into the plant. The two work synergistically: adequate nitrogen availability facilitates more efficient calcium absorption at the root zone.

The 2–0–0 NPK ratio is intentionally low in nitrogen so Pro Cal can be used across all growth stages without pushing excessive vegetative nitrogen into a flowering plant. It contributes a modest N boost that supports uptake without disrupting your overall NPK balance.

Chelated iron, manganese, and zinc are bound to organic molecules that protect them from reacting with other compounds in the nutrient solution — keeping them soluble and available for root absorption across a wide pH range. Iron is critical for chlorophyll production and enzyme activation; manganese supports photosynthesis and nitrogen metabolism; zinc is essential for hormone regulation and cell division.

Including these chelated micronutrients alongside calcium and magnesium makes Pro Cal a more comprehensive support supplement than a basic Cal-Mag formula — addressing several interrelated deficiencies that frequently occur together in fast-growing, high-demand crops.

Yes — Pro Cal is designed to supplement any GreenPlanet base nutrient program, including the GreenPlanet Nutrients 1-Part Medi One Starter Kit, and is compatible across soil, coco coir, rockwool, and hydroponic systems. It is particularly valuable in coco coir and hydroponic environments where calcium and magnesium are not naturally present in the medium and must be supplied entirely through the nutrient solution.

When stacking Pro Cal with other GreenPlanet products, account for any calcium and magnesium already present in your base nutrient formula to avoid over-supplementation. Refer to GreenPlanet's official feed charts for recommended dosing guidance within your specific nutrient program.

Calcium plays a direct role in root cell membrane integrity and permeability — the structural condition of root cells that determines how efficiently they can absorb dissolved nutrients from the surrounding solution. When calcium is deficient, root membranes become less effective at selective nutrient uptake, reducing the overall efficiency of your entire nutrient program even when other elements are dosed correctly.

By maintaining adequate calcium levels with Pro Cal, you preserve the root system's ability to absorb and translocate the full spectrum of nutrients your base program delivers — making it a foundational supplement rather than a reactive deficiency fix. For even greater nutrient mobility, consider adding GreenPlanet Nutrients GPF Uptake Fulvic Acid to your feeding regimen.