Shogun CalMag — Preventative Calcium & Magnesium Supplement for Hydroponic Growing
Best for: Coco growers, LED cultivators, and anyone running reverse osmosis water who wants to lock in consistent nutrition
Our thoughts
CalMag gets positioned as a rescue tool, but Shogun's take on it is different — it's preventative nutrition. Feed it from veg onwards and you sidestep deficiencies before they start. Built in the UK, balanced formula, works cleanly alongside the rest of the Shogun range. No faffing about.
Shogun CalMag is a liquid calcium and magnesium supplement formulated to keep plants fed throughout the growing cycle. It's not just a patch for problems — it's preventative nutrition that sits alongside your base feed from late vegetative right through to the final weeks before harvest. Contains nitrogen (2.6%), calcium (3.2%), magnesium (1.2%), and chelated iron (0.1%) in a highly bioavailable form designed for fast absorption in hydroponic systems and coco substrates.
How it compares
Sits in the mid-premium value bracket of UK-available CalMag products.
- UK-manufactured — faster delivery, no import hassle, direct support
- Balanced formula with added nitrogen, unlike zero-nitrogen competitors
- Preventative positioning rather than "rescue only" framing
- Designed to work seamlessly with the full Shogun nutrient ecosystem
- Significantly lower cost than premium US brands like General Hydroponics CALiMAGic
In practical terms: proper nutrient formulation at a price that doesn't require you to choose between CalMag and other additives.
Usage guidance
Root feed (standard method)
Add 1–2ml per litre to your reservoir, feed tank, or watering can. Use throughout vegetative and flowering stages. Stop 2 weeks before final flush. Works in any growing method — hydroponics, drip irrigation, hand watering.
Coco coir growing
Essential here. Coco has high cation exchange capacity and binds calcium and magnesium to itself, locking them away from roots. CalMag from week one ensures plants actually access these nutrients. Not optional in coco — standard practice.
LED and HPS lighting
Plants under powerful lights demand higher magnesium to support rapid growth and larger yields. Run CalMag preventatively to prevent the yellowing and stunted foliage that shows up under intensive lighting.
Reverse osmosis water systems
RO water strips out minerals. CalMag tops up baseline nutrition and stabilises pH more reliably than trying to manage pure water alone.
Correcting active deficiencies (foliar spray)
If you spot yellowing with green veins (magnesium), brown spots on young leaves (calcium), or leaf tip burn, mix at 15ml per litre and spray directly onto foliage once weekly until resolved. Maintain pH between 5–7 for foliar application.
Technical specifications
- Nitrogen: 2.6%
- Calcium: 3.2%
- Magnesium: 1.2%
- Iron (chelated): 0.1%
- Application rate (root feed): 1–2ml per litre
- Application rate (foliar spray): 15ml per litre
- Suitable pH range (foliar): 5–7
- Available sizes: 250ml, 1L, 5L, 10L bottles
- Storage: Room temperature, long-term stable
- Manufacturer: Shogun Fertilisers (UK)
Who this is for
- Coco growers at any stage — from first-time to experienced
- Anyone running LED or HPS lighting at intensity
- Growers using reverse osmosis or soft water
- Budget-conscious hydroponic cultivators who want proven UK nutrition
- Growers already using the Shogun range and wanting integrated products
- Anyone building a systematic approach to preventing deficiencies rather than reacting to them
Our take
Shogun CalMag is built on a smarter idea — use it from the start, not just when things go wrong. The nitrogen inclusion, chelated iron, and balanced calcium-magnesium ratio mean you're getting preventative nutrition that actually does work, not just a rescue product. UK manufacturer, reliable quality, clean integration with the rest of their nutrient line.
Worth picking up if you're running coco, LED, or RO water. One we recommend a lot for growers who want to lock in consistent growing conditions without guessing what's missing. Good time to buy while stock lasts.
