Greensand: The Potassium Power-up Your Soil is Missing
- Kaiju Nutrients
- Apr 10
- 4 min read
When soil is tired, depleted, and underperforming, Greensand offers a time-tested, natural solution for restoring its vitality. At Kaiju Nutrients, we’re passionate about delivering high-impact, data-backed products that improve soil performance and plant resilience. Greensand is one of the most effective long-term soil amendments we've found, and now, we’re making it available directly to UK growers. It's also salt free making Greensand The Potassium Power-up to beat.
What is Greensand?
Greensand is the powdered form of a marine mineral called glauconite. This natural substance formed over 500 million years ago on ancient seabeds from decaying marine organisms like algae, kelp, and microscopic lifeforms. Over time, these organic materials were compressed and mineralised into glauconite—a soft, green-hued rock packed with natural potassium, calcium, silica, manganese, molybdenum, boron, iron, and a number of trace minerals.
Unlike synthetic fertilisers or chemically processed additives, Greensand is organic, non-burning, and environmentally safe. It’s widely used in regenerative and organic gardening systems for its mineral density and slow-release properties. Because it doesn’t leach or break down rapidly, it feeds soil biology and plant roots steadily over an extended period.
One of Greensand’s standout features is that it contains no sulphates, chlorides, or synthetic salts. Unlike sulphate of potash, polysulphate (polyhalite), Potassium Nitrate etc Greensand delivers potassium in a gentle, non-saline form that supports long-term soil health rather than compromising it. Making it the only legit source of long term potassium. This means that organic growers dont need to compromise their organic methods.
How Does Greensand Work?
Greensand works by slowly releasing its mineral content over time. In container-grown plants, nutrients typically begin to become available within four weeks. In outdoor beds or garden soils, Greensand continues to enrich soil for up to four years with a single application.
In addition to its mineral value, Greensand is prized for its water-holding capacity, capable of absorbing up to 10 times its weight in water. This helps stabilise moisture levels in the root zone, particularly during dry spells, reducing plant stress and supporting beneficial microbial life.
Proven Performance: Soil Trial Data from a Commercial Greenhouse
We conducted a series of regenerative trials in a commercial cucumber greenhouse, comparing Greensand-treated lanes to adjacent control lanes that received conventional fertiliser inputs. or regenerative lanes with and without Greensand. Greensand was applied once at the start of the season and allowed to integrate naturally into the root zone.
Soil samples were taken at the end of the growing cycle, and the differences were unmistakable:
Key Nutrient Increases (Greensand-Treated Lanes):
Potassium (K): +161% — from 156 ppm to 407 ppm. Vital for fruiting, flowering, and internal water regulation.
Phosphorus (P): +124% — from 2.5 ppm to 5.6 ppm. Supports early root development and energy transfer.
Iron (Fe): +1,513% — from 45 ppb to 726 ppb. Essential for chlorophyll formation and deep green leaf growth.
Silicon (Si): +97% — from 3.7 ppm to 7.3 ppm. Strengthens cell walls and enhances resistance to disease and drought.
Manganese (Mn): +123% — supports chloroplast activity and enzyme systems.
Boron (B): +53% — critical for flower structure and calcium mobility.
Magnesium (Mg): +39% — the central atom in chlorophyll molecules.
Copper (Cu): +68% — involved in enzyme activation and reproductive growth.
Zinc (Zn): +13% — necessary for growth hormones and stress tolerance.
Molybdenum (Mo): increased from undetectable to 19 ppb — enabling nitrogen utilisation.
Sodium (Na): reduced by 12% — improving overall soil balance and reducing salt stress.
These mineral increases translated directly into visibly healthier plants, with stronger stems, fuller canopies, and richer green foliage compared to control lanes. As Greensand contains no phosphorus our theory is that the greensand stimulates phosphorus solubizing soil organisms accounting for the large increase in available phosphorus.
The soil technician leading the trial noted that the Greensand treated lanes were the ONLY lanes that didnt require additional inputs throughout the season along with delivering the highest quality produce!
Brix Levels Tell the Story
To validate the impact on plant health and metabolic efficiency, we conducted leaf sap testing in each lane. The results showed a consistent 1.2% increase in Brix readings (a measure of dissolved sugars and solids in plant sap) in every Greensand-treated lane.
Greensand-treated lanes: 7.0% Brix
Regenerative lanes without Greensand: 5.8% Brix
Conventional lanes: 5.5% Brix
Why does this matter? Higher Brix readings correlate with:
Enhanced photosynthesis and nutrient transport
Greater flavour and nutrient density in fruits and vegetables
Improved resistance to pests and diseases
In short, Greensand doesn’t just feed the soil—it powers the entire plant system.
How to Apply Greensand
Greensand is simple and safe to apply. It’s non-burning and suitable for all soil types.
Outdoor Beds & Raised Beds:
Apply 50g per square metre (approximately 10 lbs per 1,000 sq ft)
Mix into the top 10–15 cm of soil
Reapply every 3–4 years for ongoing soil enrichment
Container Gardening:
Mix 110g per 25 litres of soil (approx. 4.4g per litre) before planting
For lighter feeders, reduce to half the rate
Becomes plant-available within 4 weeks and supports growth throughout the season
Because Greensand is non-soluble, it won’t leach or degrade rapidly. It stays in the root zone and integrates steadily into your soil food web.
Why Greensand is Different (and Better)
Sulphate free and 100% natural
Safe for use around children, pets, and pollinators
Does not contribute to salt build-up in soil
Long-lasting—one application can support plants for up to 4 years
Rare and hard to source in the UK—now available via Kaiju Nutrients
Most importantly, it's not just theory. We've seen what Greensand can do in real conditions with real crops. The results are measurable, repeatable, and dramatic.
Where to Buy Greensand in the UK
Greensand remains an uncommon and underutilised amendment in the UK, but we import a reliable supply so that home gardeners and soil-conscious growers can experience the same results we’ve observed in our trials.
Whether you’re preparing a new garden, recharging a tired raised bed, or mixing up high-performance potting soil—Greensand is the missing mineral layer your soil has been waiting for.
We'll be adding it to the site soon so you can take your soil (and your harvest) to the next level. Get Greensand the potassium power-up as soon as it drops.
It’s time to give your plants what they really need: a deep, mineral-rich foundation that delivers season after season.
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