• Organic Liquid Magnesium — 500ml white bottle with black cap; kraft label: Dr Forest Liquid Magnesium Fertiliser 21.3% Magnesium
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Dr Forest

Liquid Magnesium 21% Mg

£19.99
£19.99
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  • ✓Free UK delivery on orders over £40
  • ✓Handcrafted and dispatched from Stockport
  • ✓Made with organic ingredients
  • ✓No-quibble returns

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Liquid micronised magnesium — certified organic suspension with fulvic acid

9% Magnesium ACO Certified Organic Contains Fulvic Acid Foliar & Soil Drench Ready-to-Dilute Liquid Recycled Plastic Bottle

This is a high-analysis liquid suspension of micronised magnesium carbonate combined with fulvic acid — a ready-to-dilute concentrate that delivers 9% magnesium in a form designed for rapid foliar and root absorption. The micronised mineral particles are held in suspension by the fulvic acid carrier, which also acts as a natural chelating agent, improving magnesium uptake and transport within the plant.

Unlike Epsom salt — which provides fully soluble magnesium that leaches within days — this suspension delivers magnesium from micronised carbonate particles that provide a slow-release trickle, feeding the plant over a longer period. The fulvic acid increases cell membrane permeability, enhances nutrient absorption, and feeds beneficial soil biology. Certified organic by ACO (Australian Certified Organic), input 456AI.

9%Magnesium (Mg)
FulvicAcid Carrier
ACOCertified Organic
LiquidReady to Dilute

What this liquid magnesium is used for

  • Correcting magnesium deficiency fast — interveinal chlorosis on older leaves is the classic symptom; foliar application delivers magnesium directly where it is needed within hours
  • Boosting photosynthesis and chlorophyll — magnesium is the central ion in every chlorophyll molecule; adequate supply directly increases sugar production and growth
  • Tomatoes, peppers, and heavy fruiters — high-potassium feeding during fruiting induces Mg deficiency via cation antagonism; regular supplementation maintains K:Mg balance
  • Roses, citrus, and ornamentals — magnesium supports colour intensity, leaf health, and overall vigour in flowering and ornamental crops
  • Foliar feed with built-in chelation — the fulvic acid carrier improves leaf cuticle penetration and enhances magnesium transport within the plant
  • Soil biology stimulation — fulvic acid feeds beneficial soil microorganisms, improving nutrient cycling and long-term soil health
  • Convenient liquid format — no powder to measure and suspend; just shake, dilute, and apply

Why a liquid suspension instead of dry powder?

Liquid Micronised Magnesium — this product

  • Pre-suspended in fulvic acid — ready to dilute with no mixing hassle
  • Fulvic acid acts as a natural chelating agent, improving Mg uptake
  • Fulvic acid increases cell membrane permeability for better foliar absorption
  • Slow-release trickle from micronised carbonate particles
  • Feeds soil biology with every application
  • ACO certified organic (input 456AI)

Dry Micronised Magnesium Powder (Micro-Mag)

  • Requires measuring, mixing, and agitation to create a suspension
  • No fulvic acid carrier — pure mineral only
  • More economical per gram of magnesium at larger volumes
  • Better for heavy broadcast soil applications (75–250g/m²)
  • Longer shelf life with no risk of settling or separation
  • Both products deliver Mg from micronised carbonate
Handcrafted in Stockport

Every Dr Forest product is made by hand in small batches at our workshop in Stockport, Greater Manchester. This product is supplied in a recycled plastic bottle.

The science: micronised magnesium carbonate + fulvic acid

Two active components working together

This product combines two distinct functional ingredients. The micronised magnesium carbonate provides a concentrated, slow-release source of magnesium from natural mineral origin. The fulvic acid acts as both a suspension carrier and a biologically active chelating agent that improves magnesium delivery to the plant.

01

Magnesium — The Chlorophyll Centre

Every chlorophyll molecule contains one Mg²⁺ ion at its centre, coordinated within a porphyrin ring. Without magnesium, chlorophyll cannot form and photosynthesis stops. Beyond chlorophyll, magnesium activates over 300 enzymes including those critical for ATP synthesis, protein production, and sugar transport to fruit.

02

Fulvic Acid — Natural Chelation & Membrane Permeability

Fulvic acid is a low-molecular-weight organic acid derived from humic substances. Its small molecular size allows it to penetrate cell membranes that larger humic molecules cannot cross. When combined with magnesium, it acts as a natural chelating agent — wrapping the mineral in an organic shell that improves absorption through both roots and leaf cuticle. Published research confirms fulvic acid increases stomatal opening, nutrient uptake, and enzyme activity.

03

Slow-Release Trickle vs Soluble Pulse

Epsom salt delivers a sharp pulse of available magnesium that peaks within hours and leaches within days. Micronised magnesium carbonate particles dissolve gradually in soil moisture, providing a sustained trickle over weeks. The fulvic acid adds an intermediate-speed delivery layer. The result is a longer feeding window from each application.

04

K:Mg Antagonism — The Container Problem

Potassium and magnesium compete for the same root uptake sites. High-potassium feeding during fruiting suppresses magnesium absorption even when soil Mg is adequate. This is the most common cause of interveinal chlorosis in container-grown tomatoes and peppers. Regular magnesium supplementation alongside potassium is the solution.

05

Soil Biology Benefits

Fulvic acid is a high-quality carbon source for rhizosphere microorganisms. It promotes beneficial bacterial and fungal populations, improves nutrient cycling, and enhances mycorrhizal colonisation. Every application feeds the plant and its soil ecosystem simultaneously.

Scientific References

  1. Cakmak, I. & Yazici, A.M. (2010). Magnesium: A forgotten element in crop production. Better Crops, 94(2), 23–25.
  2. Nardi, S. et al. (2009). Physiological effects of humic substances on higher plants. Soil Biol. Biochem., 34, 1527–1536.
  3. Verbruggen, N. & Hermans, C. (2013). Physiological and molecular responses to magnesium nutritional imbalance. Plant and Soil, 368, 87–99.
  4. Guo, W. et al. (2016). Magnesium deficiency in plants: An urgent problem. The Crop Journal, 4(2), 83–91.

How to use liquid micronised magnesium: application rates & guide

Shake well before every use

This is a mineral suspension, not a true solution. Shake the bottle vigorously for 15–20 seconds before each use. When diluting, add the concentrate to a small amount of warm water (20–30°C) first and stir well before adding the remaining water.

Application rates

Foliar spray

Rate: 3–6 ml per litre of water  |  Frequency: Every 2–4 weeks during the growing season

Apply as a fine mist to both leaf surfaces in early morning or late evening. Ensure thorough coverage including leaf undersides. The fulvic acid improves leaf cuticle penetration. Visible improvement in chlorosis typically appears within 7–14 days.

Soil drench — root zone application

Rate: 6–10 ml per litre of water  |  Frequency: Every 2–4 weeks during the growing season

Dilute and apply directly to the root zone. Water in afterwards. Use the higher rate (10 ml/L) for visibly deficient plants or known-low Mg soils. Use the lower rate for maintenance feeding.

Intensive correction — deficient crops

Rate: 10 ml per litre (soil) or 6 ml per litre (foliar)  |  Frequency: Every 2–3 weeks until symptoms resolve

Combine foliar and root applications for fastest correction — foliar for immediate leaf response, root drench for sustained soil-level replenishment.

Step-by-step preparation

  1. Shake the bottle vigorously for 15–20 seconds. The particles settle during storage — thorough shaking is essential.
  2. Measure the concentrate. For a 10-litre watering can: 30–60 ml for foliar spray, or 60–100 ml for soil drench.
  3. Add to a small amount of warm water first (20–30°C) and stir well, then add the remaining water.
  4. Apply immediately. Foliar: fine mist to both leaf surfaces. Soil: evenly around the root zone.
  5. Store sealed between 5–25°C, away from direct sunlight. Shake before every use.
Works well combined with…

Pair with Seaweed Powder in a foliar tank mix — alginic acid improves leaf wetting while fulvic acid enhances uptake. Use alongside any Dr Forest crop-specific fertiliser where additional magnesium is needed. Combine with Cal-Mino for a foliar calcium + magnesium programme during fruiting.

Frequently asked questions

Both deliver magnesium from micronised magnesium carbonate. This liquid comes pre-mixed with fulvic acid — shake, dilute, and apply. Micro-Mag is a dry powder you mix yourself. The liquid is more convenient for foliar and small-volume use. The powder is more economical for heavy broadcast. The fulvic acid in the liquid adds chelation and biology benefits the powder alone does not provide.
Three things. First, it keeps the micronised particles suspended in the liquid. Second, it is a natural chelating agent — it wraps mineral ions in organic molecules that pass through cell membranes more easily. Third, it feeds beneficial soil microorganisms, stimulating biological activity and nutrient cycling.
For most garden applications, yes. Epsom salt is fully soluble but leaches rapidly. This product provides sustained release from micronised carbonate plus fulvic acid chelation and biology benefits. Epsom salt does also provide sulphur — useful where both Mg and S are deficient.
This is a mineral suspension — micronised particles held in a liquid carrier. The particles settle during storage. Shaking for 15–20 seconds resuspends them evenly for consistent dosing. This is normal for all suspension products.
Yes. Certified organic by ACO (Australian Certified Organic), registered farm input 456AI. The magnesium is from natural magnesium carbonate and the fulvic acid is a natural humic extract. No synthetic chemicals.
Non-toxic when used as directed. Avoid ingestion and eye contact. Wash hands after handling. Once applied and watered in, treated areas are safe for normal use.
This is a suspension, not a true solution — fine particles will be present. Suitable for drip irrigation with adequate filtration, but may cause issues in fine-tolerance recirculating systems. For NFT and DWC, a fully soluble source like Epsom salt may be more practical.
This product is supplied in a recycled plastic bottle. Please recycle after use through your local collection.
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