How to make JADAM Microbial Solution at home
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How to make JADAM microbial solution at home
By Joe, Founder of Dr Forest · June 2026
The microbes you want in your beds already live a few hundred metres away, in the leaf litter under the nearest mature tree.
JADAM microbial solution, JMS for short, is a homemade microbial inoculant. You make it by fermenting a handful of forest leaf mould with a boiled potato in lightly salted water for one to three days. The leaf mould brings the microbes, the potato feeds them, and after a couple of days you have a bucket of living soil organisms to drench across your beds. It costs pennies a litre and needs no special kit.
It comes from JADAM, the ultra-low-cost organic system the Korean farmer Youngsang Cho set out in 1991, building on the natural-farming tradition his father Hankyu Cho started. This guide covers what JMS is, the recipe I use, how to brew it, what is actually happening in the bucket, and how to apply it. Most of what you need you already have.
JMS at a glance
What it is
A one to three day anaerobic ferment of forest leaf mould, water, salt and a boiled potato. Pennies a litre, brewed in a bucket, ready when a disc of foam forms on top.
What it does
Multiplies the microbes already living in your local soil and lets you spread them across the garden. Cho's main use is to prepare a bed before planting: three drenches in the run-up to sowing, to settle the soil biology early and push roots deeper.
It grows soil biology rather than feeding the plant directly. Treat it as the living half of a plan that still needs real nutrition alongside.
From the range
EM-1 Effective Microorganisms — a ready-made probiotic culture, if you would rather buy the biology than brew it. £25.
What JADAM microbial solution is
A handful of forest leaf mould holds an enormous microbial community: bacteria and fungi in their thousands of species, plus protozoa, nematodes and archaea. Most vegetable beds underperform on biology long before they run short on fertility. JMS is a way to take some of that forest community, multiply it overnight, and pour it onto ground that has less.
It is a homemade inoculant rather than a defined product. What ends up in the bucket is whatever already lives in your patch of woodland, not a fixed culture from a bottle, which is the point and also the catch: every batch reflects its own source and varies a little. That variability is why JMS suits gardeners who want to work with their own ground rather than import a standardised blend from elsewhere.
A fair answer to a common questionWhat microbes are in it
This is the part people most want pinned down, and the honest answer is that it depends on your leaf mould. JMS is a wild ferment, not a laboratory culture, so no two buckets carry exactly the same organisms and the full community has not been characterised in independent peer-reviewed work.
What the method does is select. The light salt and the low-oxygen conditions favour organisms that tolerate both, which in practice means a community leaning towards facultative anaerobes and lactic acid bacteria, the same broad groups you find in many traditional ferments. The fungi, protozoa and other organisms from the leaf mould ride along too. If you have read claims that JMS is a defined dose of named species, treat them with caution. What you can say with confidence is that it is a live, mixed, locally-adapted community, brewed up to a high population just before you apply it.
Scaled to a 4-litre batchThe recipe
Cho's original uses four ingredients: water, leaf mould, salt and a potato. The version below keeps that base and adds two optional boosters that round out the mineral side of the brew. Four litres is enough for one bed of around five square metres once diluted.
What goes in a 4-litre batch
| Ingredient | Per 4L | What it does |
|---|---|---|
| Rainwater or rested tap water | 4 L | The carrier. Tap water needs 24 hours to off-gas chlorine, which kills microbes. |
| Boiled potato, blended to a puree | 25 g | Starch food source for the microbial bloom. |
| Sea salt | 4 g | A mild selection pressure, roughly a 0.1% solution. |
| Forest leaf mould | 4–8 g | The inoculum, taken from below the leaf litter under a mature tree. |
| Volcanic rock dust (optional) | 40 g | Trace minerals the microbes use to function. |
| Humic acid (optional) | 1.6 g | A longer-chain carbon source that feeds microbes once the potato is spent. |
On sourcing leaf mould: take it from below a well-established tree in healthy woodland or an old hedgerow, the dark crumbly layer under the recently fallen leaves that often looks like worm castings. A small handful from the top inch is plenty. Avoid playing fields, roadsides, and anywhere that may have been sprayed.
From bucket to bedHow to make it, step by step
Figure 1 · The JMS brew
Four stages from a handful of leaf mould to a working drench
A wild ferment that peaks fast and has no shelf life worth speaking of.
Schematic illustrative. Timing shifts with temperature: faster in summer, slower in a cold spring.
- Fill a 5-litre bucket with 4 litres of water. Rainwater, or tap water left out for 24 hours.
- Stir in the salt and rock dust. The water will go slightly cloudy.
- Add the potato puree. Mash it in thoroughly, as more surface area means faster colonisation.
- Stir in the humic acid if using. It is a powder and disperses easily.
- Knead in the leaf mould. Some growers tie it in a mesh bag suspended in the water, others stir it loose. Either works.
- Cover loosely. A breathable lid or a tea towel lets gas escape and keeps fresh oxygen low.
- Hold at 18 to 22°C. A shed with a heat mat in winter, a south-facing windowsill in spring. Below 18°C the ferment stalls; above 25°C you start losing strains.
- Watch for the raft, then use it within 24 to 48 hours. Once that foam disc starts to break up, the microbes are dying back. JMS has no useful shelf life.
Why the method works
Every part of the recipe is doing a job. The leaf mould is the seed culture. The potato starch is quick food, so the population can double through the brewing window. The salt sets a mild stress that favours tolerant organisms and dampens the runaway opportunists. And the loose lid holds oxygen low, which selects for the organisms that thrive in heavy, compacted soils rather than the ones that only do well in open air.
The foam raft is your gauge. Those bubbles are carbon dioxide coming off an active ferment, and when they coalesce into a continuous disc the population is near its peak. That is the window to apply, because a wild brew like this has nothing to hold it there. Leave it a few days more and the food is gone, the community crashes, and what is left is whatever survives in a depleted bucket.
You are not buying microbes. You are growing the ones already in your soil.
How to apply it
JMS is used fresh and diluted. The numbers below are the JADAM starting points; adjust down for young plants. Cho's primary recommendation is to drench a bed three times before planting, which settles the soil biology early and encourages deeper rooting.
How to dilute and when
| Use | Dilution | How and when |
|---|---|---|
| Soil drench | 1:10 | 1 litre of JMS in 10 litres of water, at 5 to 10 litres per square metre. Bare soil with nothing growing yet can take it at full strength. |
| Foliar spray | 1:20 | 1 litre in 20 litres, with a wetting agent. Spray to runoff in the early evening when stomata are open and UV is low. |
| Pre-planting | 3 drenches | Cho's core use. Three drenches across the two weeks before transplanting, to prime the bed and drive roots deeper. |
| Maintenance | Monthly | Through the season, stepping up to weekly in the fortnight before flowering or fruit set. |
If you want to spray it on leaves, pair it with a wetting agent so the solution sits on the leaf rather than beading off. Do not apply at full strength to seedlings. Stick to 1:10 on anything younger than four true leaves, and 1:20 on early seedlings.
JMS against the bought alternativesWhere JMS fits
JMS is a microbial input, not a fertiliser. The nutrient load from a 1:10 drench is negligible, so its job is to keep the soil ecosystem populated alongside whatever feeding plan you already run. If you have used a bought inoculant such as Dr Higa's Organic EM-1 or a bokashi bran, JMS is the make-your-own version of the same idea, at a fraction of the cost.
JMS and the cultured alternatives
| JMS | EM-1 | Bokashi bran | Compost tea | |
|---|---|---|---|---|
| Microbial source | Local leaf mould | Cultured EM blend | Cultured EM on bran | Mature compost |
| Type | Anaerobic ferment | Mixed culture | Solid fermented bran | Aerobic brew |
| Cost | Pennies per litre | About £1 per litre | About £15 per kg | Free with compost |
| Shelf life | 24 to 48 hours | 12 months | 12 months | A few hours |
| Consistency | Varies by source | Reproducible | Reproducible | Varies by compost |
Brew JMS
You already work closely with your own soil and want to amplify what is there. A forest walk and a bucket cost almost nothing, and the brew adapts to your exact ground.
Reach for EM-1 or bokashi
You want a consistent, reproducible culture with a long shelf life and no brewing window to catch. Both use Professor Teruo Higa's Effective Microorganism blend, developed in Okinawa in the 1980s.
The two are not at odds. Many growers keep a bottle of EM-1 for convenience and brew JMS in the growing season for cheap volume. JMS also pairs well with three things you may already have on the shelf: a mycorrhizal inoculant worked into the root zone at transplanting, not into the brew, since mycorrhizae need living roots and will not survive a bucket ferment; volcanic rock dust on the bed for trace minerals; and humic acid as a longer-term carbon source.
Where to keep your expectations honestA few honest caveats
Cho reports that consistent JMS use settles transplanted roots faster, and the root-establishment effect is the best supported of his claims and fits what is known about microbial priming. He also reports effects on soil salinity and on soil-borne problems such as nematodes and wilting. The independent peer-reviewed evidence for those is thin, and the underlying principle, that a thriving soil community out-competes opportunists, is better established than any specific figure. If your soil is heavily salt-loaded from de-icing or coastal spray, deal with the cause rather than expecting a brew to remediate it.
The other honest point is variability. Your leaf mould is a wild inoculum, so two batches from two woods will differ. That is part of the appeal, since you are cultivating microbes suited to your own climate, but it does mean results are not perfectly repeatable. Treat JMS as one input in a soil-first plan, not a single fix.
Cultured microbes, ready when you are
JMS is the cheapest way to put life back in your soil. When you want consistency or have missed the brewing window, our EM and bokashi range does the same job from a reproducible culture, made with organic ingredients in Stockport, Greater Manchester.
Browse the full EM and bokashi range.
On borrowing from the woods
The first time you brew JMS, the thing that stays with you is how little it asks. A handful of leaf mould off a damp woodland floor, a boiled potato, a pinch of salt, a couple of warm days in the shed. Then a bucket of foam that goes onto a bed of seedlings and gets to work. The microbes were always there. JMS is just the lift from the woods to your garden.
Frequently asked
Frequently asked questions
What is JADAM microbial solution (JMS)?
JADAM microbial solution (JMS) is a homemade microbial inoculant made by fermenting forest leaf mould with a boiled potato in lightly salted water for one to three days. The leaf mould supplies the microbes and the potato feeds them, leaving a bucket of indigenous soil organisms ready to drench across your beds. It is a foundational input in JADAM, the low-cost organic system founded by Youngsang Cho in 1991.
What is the JMS recipe?
For a 4-litre batch: 4 litres of rainwater or rested tap water, 25g of boiled potato blended to a puree, 4g of sea salt, and a small handful (4 to 8g) of forest leaf mould. Optional additions are 40g of volcanic rock dust and 1.6g of humic acid. Ferment loosely covered at 18 to 22°C for one to three days, until a disc of foam forms across the surface.
How long does JMS take to brew?
One to three days at 18 to 22°C. In summer it can finish in 24 hours; in a cold spring it may need three days or a heat mat. The signal that it is ready is a continuous raft of foam across the surface, and you should use it within 24 to 48 hours of that raft forming.
What microbes are in JADAM microbial solution?
JMS is a wild ferment rather than a defined culture, so the exact community depends on your leaf mould and has not been fully characterised in independent peer-reviewed work. The salt and low-oxygen conditions select for tolerant organisms, which in practice leans towards facultative anaerobes and lactic acid bacteria, alongside the fungi and other organisms carried in from the leaf mould. Treat any claim of a fixed list of named species with caution.
Where do I find leaf mould?
Below the layer of recently fallen leaves under a mature tree, in healthy woodland or an old hedgerow. Brush the top leaves aside and you should see a dark crumbly material that often looks like worm castings. Take a small handful from the top inch, and avoid playing fields, roadsides, and any land that may have been sprayed with herbicide.
Does JMS replace fertiliser?
No. JMS is a microbial input, not a fertiliser, and the nutrient load from a 1:10 drench is negligible. It works alongside your usual feeding plan by keeping the soil ecosystem active, which helps plants take up the nutrients you do supply.
Is JMS the same as JADAM Sulphur?
No. They are two different JADAM preparations. JMS is the microbial ferment described here. JADAM Sulphur is a separate wettable-sulphur preparation made for plant surfaces, and it is not a microbial input. This guide covers JMS only.
Why hasn't my JMS formed a raft?
Usually one of three reasons. The water was too cold, since below 18°C the ferment stalls. The water was chlorinated and the microbes died at the start, so always rest tap water for 24 hours or use rainwater. Or the leaf mould was too old or dried out and the microbial load was too low. Try again with fresh leaf mould from a damp patch of woodland and a bucket somewhere warm.
Is JADAM microbial solution the same as EM-1 or bokashi?
No. EM-1 and bokashi bran are bought products built on a fixed culture, mostly lactic acid bacteria, yeasts and phototrophic strains. JMS is a homemade inoculant that grows whatever already lives in your local leaf mould, so every batch reflects your own ground and varies a little. They work well together: a bought inoculant gives you consistency, while JMS gives you low-cost volume and local adaptation.
Sources cited
The working, shown
- Cho, Youngsang. JADAM Organic Farming: The Way to Ultra-Low-Cost Agriculture. JADAM Organic Farming Institute, 2016.
- JADAM Organic Farming Institute. How to make JADAM Microorganism Solution (JMS). en.jadam.kr.
- JADAM Organic Farming Institute. Introduction to JADAM. en.jadam.kr.
- Higa, T. and Parr, J.F. (1994). Beneficial and Effective Microorganisms for a Sustainable Agriculture and Environment. International Nature Farming Research Center, Atami, Japan.
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1 comment
Thanks for the article! I am just wondering IF there are possibilities to keep this mixture forever by feeding the microbes. Take some out when the raft is well formed and mixture is ready and loaded up it again with steps 1-8 or better start over again?
Thanks!