Green Planet Pro Cal | Calcium Magnesium Supplement | 1L, 5L, 20L

The Cal-Mag Supplement Every Hydroponic Grower Needs

Green Planet Pro Cal is a professional-grade calcium and magnesium supplement designed to be used throughout your entire grow — from early veg right through to the final week before flush. Formulated with a readily available calcium source, extra magnesium, and fully chelated iron, Pro Cal keeps your plants structurally strong, photosynthetically efficient, and free from deficiency at every stage.

Why Growers Rely on Pro Cal

• Thickens & strengthens cell walls — calcium forms the structural glue that holds cells together, essential for healthy new growth
• Boosts photosynthesis — magnesium is the central core of the chlorophyll molecule, directly powering your plant's energy production
• Improves nutrient absorption & translocation — calcium enhances root uptake and helps move nutrients throughout the plant
• Fully chelated iron — maximises iron availability and prevents deficiency-related yellowing
• Noticeable size increase — stronger cell walls and better nutrient flow means visibly bigger, denser growth
• Improved enzyme function — supports the biochemical processes that drive vigorous plant performance
• Helps form calcium pectate — critical for cell wall integrity and resistance to disease
• Coco coir approved — essential for coco growers where Ca & Mg are naturally depleted by the medium
• Powerful, readily available formula — Ca and Mg in plant-transportable forms for fast uptake

How It Works

Calcium and magnesium are two of the most critical secondary nutrients in plant growth — but they're also among the least mobile within the plant. This means your plants need a constant, readily available supply they can easily uptake and transport.

Calcium forms calcium pectate, the structural compound that binds cell walls together. Without adequate calcium, new growth suffers, cell walls weaken, and your plant becomes vulnerable to disease and stress. Calcium also plays a key role in activating root enzymes that drive nutrient absorption.

Magnesium sits at the centre of every chlorophyll molecule in your plant. Without it, photosynthesis breaks down, leaves yellow (interveinal chlorosis), and energy production drops — directly impacting growth rate and yield.

Pro Cal delivers both in a highly bioavailable, plant-transportable form, paired with fully chelated iron to round out the micronutrient profile and keep your plants green, strong, and thriving from day one.

How to Use

• Vegetative stage: Apply at 1.2 ml per litre throughout veg
• Flowering stage: Increase to 1.8 ml per litre throughout bloom
• Stop use the week before flush — use with Rezin and water during flush week
• Compatible with all hydroponic systems, coco coir, and soil grows

💡 Pro Tip: Pro Cal is an essential part of the Green Planet nutrient program. Pair with GP3 Grow, GP3 Micro, and GP3 Bloom for a complete, deficiency-free feeding system from seed to harvest.

Available Sizes

Available in 1L, 5L, and 20L — suitable for home growers and large-scale commercial operations.