• Liquid Silica Fertiliser — 500ml white bottle with ribbed cap, kraft label: Dr Forest Liquid Diatomaceous Earth Fertiliser 12.5% Silicon
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Plant Silica

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Liquid micronised diatomaceous earth — 90% amorphous silica with boron

90% Amorphous Silica 0.7% Boron Synergist ACO Certified Organic Foliar & Fertigation Micronised Suspension Recycled Plastic Bottle

Silicon is the most abundant mineral element in the earth's crust after oxygen — and the most neglected in plant nutrition. It strengthens cell walls, improves drought tolerance, increases resistance to fungal disease and insect feeding, enhances flowering and fruit set, and acts as a general tonic for plant health. Yet almost no fertiliser programme includes it. This product solves that gap: a liquid suspension of micronised diatomaceous earth delivering 90% amorphous silica in plant-available form.

Diatomaceous earth (DE) is the fossilised remains of diatoms — single-celled aquatic organisms whose cell walls are made of silica. Micronising these fossils into ultra-fine particles and suspending them in liquid creates a form of silicon that can be applied as a foliar spray or fertigation input. The formula also includes 0.7% boron — a documented silica synergist that improves silicon uptake and supports reproductive development. ACO certified organic (456AI).

90%Amorphous Silica
0.7%Boron (B)
ACOCertified Organic
SafeAmorphous Form

What liquid silica is used for

  • Strengthening cell walls against disease — silicon deposits in the outer cell wall as amorphous silica, creating a physical barrier that fungal hyphae and insect mouthparts struggle to penetrate; documented to reduce powdery mildew, botrytis, and aphid damage
  • Improving drought and heat tolerance — silicon thickens the cuticle and reduces transpiration losses; silicified plants maintain turgor and photosynthesis under water stress that would wilt untreated plants
  • Increasing flowering and fruit set — silicon and boron together support pollen viability, pollen tube growth, and fruit cell division; the 0.7% boron acts as a documented silica synergist
  • Boosting yield and quality — silicon-supplemented crops consistently show increased biomass, improved fruit firmness, better colour, and longer shelf life in published research
  • Turf and grass health — silicon is particularly important for grasses; it strengthens stems, improves wear tolerance, and increases resistance to fungal disease in lawns, sports turf, and pasture
  • General plant tonic — silicon plays a role in photosynthesis, nutrient uptake, and stress signalling; it improves the overall health and resilience of any crop, even when no specific deficiency symptoms are visible
  • Compatible with other inputs — unlike potassium silicate (which is highly alkaline and incompatible with most fertilisers), micronised DE can be tank-mixed with a wide range of products

Why micronised DE instead of potassium silicate?

Micronised Diatomaceous Earth — this product

  • 90% amorphous silica from natural fossilised diatoms
  • Compatible with most other fertiliser inputs
  • Includes 0.7% boron as a silica synergist
  • Contains a broad range of natural micronutrients from the DE source
  • ACO certified organic
  • No alkalinity issues — safe pH for tank mixing

Potassium Silicate

  • Highly alkaline (pH 11–13) — incompatible with most other inputs
  • Precipitates when mixed with calcium, phosphate, or acidic solutions
  • No boron, no micronutrients — silicon only
  • Must be applied alone or as the last input in a tank mix
  • Risk of leaf burn at higher concentrations due to alkalinity
Handcrafted in Stockport

Every Dr Forest product is made by hand in small batches at our workshop in Stockport, Greater Manchester. We source ingredients for quality, not cost. Supplied in recycled plastic bottles.

The science of silicon: the forgotten plant nutrient

Why silicon is missing from most fertility programmes

Silicon is not classified as an essential plant nutrient under the strict Arnon and Stout criteria — plants can complete their life cycle without it. But this technical classification has led to a practical blind spot. Research over the past two decades has consistently demonstrated that silicon supplementation improves cell wall strength, disease resistance, drought tolerance, yield, and quality across a wide range of crops. It is now classified as a "beneficial element" and is included in many advanced nutrition programmes worldwide. The problem has always been delivery: how to get silicon into a plant-available form that is compatible with other inputs.

01

Cell Wall Reinforcement

Silicon is absorbed by roots as monosilicic acid (Si(OH)₄) and transported to the shoot where it polymerises in the outer cell wall as amorphous silica (SiO₂·nH₂O). This creates a physical barrier — essentially a layer of biological glass — beneath the cuticle. Fungal hyphae must penetrate this barrier to infect the tissue. Insect mandibles and stylets encounter a hard, abrasive surface. Research consistently shows that silicon-supplemented plants have significantly lower rates of powdery mildew, botrytis, rice blast, and other foliar diseases.

02

Drought and Heat Tolerance

The silica layer in cell walls reduces cuticular transpiration — the passive loss of water through the leaf surface. Silicon also improves root water uptake under osmotic stress and maintains cell turgor at lower water potentials. Published studies demonstrate that silicon-treated plants maintain photosynthesis and biomass production under drought conditions that significantly reduce performance in untreated controls. For container-grown crops where water stress cycles are common, this translates directly to improved resilience and reduced watering frequency.

03

Boron as a Silica Synergist

Recent research has identified boron as a key synergist for silicon uptake and utilisation. Boron improves the deposition of silicon in cell walls and enhances the structural benefits. This formula includes 0.7% boron specifically for this synergistic effect. Boron also has its own critical role: it is required for pollen tube growth, sugar transport, and cell wall structure. However, boron has a narrow window between deficiency and toxicity — the 0.7% concentration is calibrated for synergistic benefit without accumulation risk at recommended application rates.

04

Amorphous vs Crystalline Silica — Safety

The silica in diatomaceous earth is amorphous — a non-crystalline form with no associated health risks. This is fundamentally different from crystalline silica (quartz), which is a documented respiratory hazard. Amorphous silica from diatomaceous earth is classified as safe for agricultural use and is approved under organic certification standards. The micronised particle size improves plant availability without creating any crystalline silica exposure.

05

Flowering, Fruit Set & Quality

Silicon supplementation has been shown to increase flowering intensity, improve fruit set rates, and enhance fruit quality across multiple crop species. The mechanisms include improved pollen viability (enhanced by the boron synergist), stronger peduncle and pedicel tissue, and firmer fruit cell walls. Silicon-treated fruit consistently shows improved firmness, colour, sugar content, and post-harvest shelf life — all traceable to the structural and metabolic benefits of silicon deposition in developing tissue.

06

Micronutrient Payload

Diatomaceous earth is not pure silica — it is the fossilised remains of aquatic organisms that accumulated a range of trace elements during their lifetime. The micronised DE in this product contains a broad spectrum of micronutrients alongside the dominant silica fraction. While silicon is the primary active ingredient, the micronutrient content provides additional nutritional value that pure silicon sources like potassium silicate cannot match.

Scientific References

  1. Ma, J.F. & Yamaji, N. (2006). Silicon uptake and accumulation in higher plants. Trends in Plant Science, 11(8), 392–397.
  2. Liang, Y. et al. (2007). Importance of plant species and external silicon concentration to active silicon uptake and transport. New Phytologist, 172(1), 63–72.
  3. Epstein, E. (1999). Silicon. Annual Review of Plant Physiology and Plant Molecular Biology, 50, 641–664.
  4. Savvas, D. & Ntatsi, G. (2015). Biostimulant activity of silicon in horticulture. Scientia Horticulturae, 196, 66–81.
  5. Mattson, S.E. & Leatherwood, W.R. (2010). Potassium silicate drenches increase leaf silicon content and affect morphological traits. HortScience, 45(1), 43–47.

How to use liquid micronised silica: application rates & guide

Boron warning — do not exceed recommended rates

This product contains 0.7% boron. Boron is beneficial at correct rates but toxic to plants at high levels. Do not exceed the application rates below. Monitor plant boron levels if applying regularly or at the upper end of the rate range. Some crops (particularly beans and peas) are more sensitive to boron than others — test-spray a small area first.

Application rates — professional & commercial

Foliar spray — horticultural crops & turf

Rate: 10 ml per litre of water (1 L per 100 L)  |  Max per hectare: 5 L/ha

Apply every 2–4 weeks or as required during the growing season. Ensure thorough foliage coverage. Where higher water volumes are needed for canopy penetration, do not exceed the maximum product rate per hectare. Particularly effective from pre-flower through to fruit fill.

Broadacre crops

Rate: 1–2 L/ha in 60–100 L water  |  Frequency: As required

Adjust water volume depending on canopy closure. Apply at key growth stages based on crop monitoring. Silicon is particularly valuable at tillering in cereals and pre-flower in all crops.

Fertigation

Rate: 5–20 L/ha  |  Frequency: As required

Apply through drip systems or irrigation. Use the higher rate for initial soil loading; lower rates for maintenance. Maintain agitation in the mixing tank. Use a coarse inline filter (500 micron / 35 mesh).

Application rates — home garden

Foliar spray & soil drench

Rate: 45 ml per 9-litre watering can  |  Coverage: Apply 1 litre of diluted mix per m²

Shake well before use. Dilute 45 ml into a 9-litre watering can. Apply as a foliar spray to both leaf surfaces, or pour over foliage and root zone as a combined drench. Repeat every 2–4 weeks during the growing season as required.

Step-by-step preparation

  1. Shake vigorously for 15–20 seconds. The mineral particles settle rapidly during storage.
  2. Measure the required volume. Home garden: 45 ml per 9L watering can. Professional: 10 ml per litre of spray solution.
  3. Add to warm water (20–30°C) and stir vigorously for 30 seconds before topping up. This ensures thorough mixing.
  4. Apply immediately. For foliar spraying, target both leaf surfaces in early morning or late evening. Maintain agitation in sprayers.
  5. Clean equipment after use. Flush sprayers with clean water. The mineral particles can settle and clog nozzles if left to dry.
Visible residue on foliage

Micronised mineral suspensions leave a visible white residue on leaves and fruit after spraying. This is normal — it is mineral particles on the leaf surface. If produce appearance matters close to harvest, switch to soil drench application or spray earlier in the growing season.

Works well combined with…

Pair with Cal-Mino for chelated calcium during fruiting — calcium and silicon together produce the strongest cell walls. Use alongside Seaweed Powder for additional biostimulant activity. Compatible with most Dr Forest fertiliser inputs. Avoid mixing with strongly acidic solutions — perform a jar test before combining with any new product.

Frequently asked questions

The source material is similar — fossilised diatomaceous earth — but this product is micronised into ultra-fine particles and suspended in liquid specifically for plant nutrition. Food-grade DE is a coarse powder used for pest control and other purposes. The micronisation is what makes the silicon plant-available; coarse DE powder does not deliver silicon to plants effectively.
Yes. The silica in diatomaceous earth is amorphous — a non-crystalline form with no associated health risks. This is fundamentally different from crystalline silica (quartz), which is a documented respiratory hazard. Amorphous silica is approved for agricultural use and is classified as safe under organic certification standards.
Boron has been identified as a silica synergist — it improves the deposition and utilisation of silicon in plant cell walls. Including 0.7% boron in the formula enhances the structural benefits of the silicon. Boron is also essential in its own right for pollen tube growth, sugar transport, and cell wall integrity. However, boron can be toxic at high levels — do not exceed the recommended application rates.
Yes. Silicon deposits in the outer cell wall create a physical barrier that fungal hyphae must penetrate. Published research consistently demonstrates significant reductions in powdery mildew, botrytis, and other foliar diseases in silicon-supplemented crops. It is not a fungicide — it is a structural defence that makes infection harder for the pathogen.
Potassium silicate is highly alkaline (pH 11–13) and incompatible with most other fertiliser inputs — it precipitates when mixed with calcium, phosphate, or acidic solutions. It must be applied alone. Micronised diatomaceous earth avoids this problem: it is compatible with most tank-mix partners, includes boron and micronutrients that potassium silicate lacks, and is ACO certified organic.
Technically no — plants can complete their life cycle without it, which is why it is not classified as "essential" under the strict definition. But it is classified as a "beneficial element" and decades of research demonstrate measurable improvements in cell wall strength, disease resistance, drought tolerance, flowering, fruit quality, and yield. Many advanced nutrition programmes now include silicon as standard practice.
All plants benefit, but grasses (including turf, cereals, and sugar cane) are the highest silicon accumulators and show the most dramatic responses. Among garden crops, cucurbits (courgettes, cucumbers, squash), tomatoes, strawberries, and roses respond particularly well. Silicon is also highly effective on any crop prone to powdery mildew or where drought stress is a recurring issue.
Yes. Micronised mineral suspensions leave a visible white residue on foliage and fruit. This is harmless mineral deposit. If produce appearance matters close to harvest, use soil drench instead of foliar spray, or time foliar applications earlier in the growing season.
Store upright in a cool, dry place between 5–25°C, out of direct sunlight. Keep sealed. Shake vigorously before each use. Do not store below 5°C — sedimentation may occur. Do not store diluted — mix fresh for each application.
Yes. This product is supplied in recycled plastic bottles.
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