Most growers throw away their medium every cycle. Living-soil growers do the opposite: the same batch of soil gets better each time it is recycled, and the root balls from the last harvest are the raw material. This article summarises the recycling method in The Rev’s True Living Organics (Green Candy Press; first edition 2012, second edition 2016, third “Druid’s Edition” 2024). It covers the book’s batch basis, how it adjusts for water quality, and what is and is not verified about curing time and pathogen safety.
1. What recycling actually is
At the end of a cycle you have a pot full of soil held together by a dead root mass. Recycling means four steps:
- break that mass apart and let the roots decompose
- replace the mineral and organic fertility the last crop removed
- cure the result until it is safe for a new plant
The no-till topic on this forum (topic 1091) covers the alternative in depth, so here is just the core difference: no-till leaves the soil in the pot and rebuilds fertility from the top; recycling empties the pot and rebuilds the whole batch. No-till keeps an undisturbed fungal network and needs less work each cycle. Recycling takes more work, but it lets you:
- correct a mix that has drifted
- remove a root mass that is blocking a small pot
- blend several pots into one even batch
Most indoor growers using small containers end up recycling. Ground beds and large fabric beds suit no-till.
2. Preparing the raw material
- Tip the root balls into a bin. The author prefers an insulated cooler with a drain plug, but a plastic tub, a builder’s tray or a paddling pool also works.
- Break the root mass up with a spade.
- Wet it down so it is evenly moist, not saturated.
- Leave it uncovered, or at least with the lid ajar. Never seal a living-soil container.
Design against two ways this can fail:
- Overwatering. It makes the bin anaerobic fast. You will smell it, and the compounds anaerobic organisms produce can damage roots in the next cycle. This is why a drain plug matters.
- Sealing the container. It starves the aerobic organisms that do the decomposing.
Chop or shred anything bulky first. Stems, trim, leaves and kitchen scraps all recycle, but coarse material slows the process.
Do not recycle: soil and root balls from plants that had root rot, Pythium or Fusarium, or heavy pest problems. Hot-compost that material properly or throw it out. Do not put it back into the recycling bin, because an ambient cure will not clean it up. See topic 1263 on this forum.
Tropical note: in Thai heat and monsoon rain, an open bin of blood meal, bone meal and kitchen scraps attracts flies, ants, rats and fungus gnats, and rain can waterlog it. Keep the bin under cover. Use a lid that lets air through, plus fine mesh to keep flies and rodents out. At 30–35 °C, expect curing to go faster than any temperate-climate schedule, and judge readiness by checking the soil, not by counting days.
3. The recycled soil mix — a summary of the book’s recipe
The book’s recipe is built around a batch of 85–100 litres of recycling material (used soil, root balls, stems, shredded leaves, kitchen scraps). For other batch sizes, scale it in proportion. In outline, the amendments do these jobs:
| Function | Ingredients the book uses |
|---|---|
| Fast nitrogen | Blood meal, bird/bat guano |
| Slower nitrogen | Feather meal, alfalfa meal (optional) |
| Phosphorus | Bone meal, soft rock phosphate |
| Calcium, magnesium, pH buffering | Dolomite lime (powdered and prilled), crushed oyster shell, gypsum |
| Potassium and trace minerals | Kelp meal, Azomite, greensand |
| Structure and extras (optional) | Rinsed coco coir, natural rice, humic acid ore, well-composted manure |
Added together, the book’s dry amendments come to roughly 6 litres per batch, or about 6–7% of the batch by volume. Feather meal, bone meal, kelp meal and oyster shell are the largest single items. For exact amounts per ingredient, see the book itself.
To mix, the author combines all the amendments with one-third to one-half of the soil first, then adds the rest. In a tumbler, a few full rotations is enough to start, and repeated turning over the following weeks evens the mix out further.
4. Adjusting for your water — the part most people skip
The recipe assumes very pure irrigation water, under about 10 PPM TDS. If your tap or well water carries dissolved minerals, you add calcium and magnesium every time you water, and the recipe’s lime and shell load becomes too much. In summary, the author’s rule is:
- moderately mineralised water: reduce the dolomite and oyster shell
- hard well water: reduce them much more, and also cut back the bone meal
The idea applies well beyond this recipe: the mineral content of your water is part of your fertiliser programme whether you account for it or not. A TDS meter is cheap. Measure your source water before you build any living-soil recipe, and treat the reading as an input.
For growers in Thailand and Southeast Asia, where cultivation is legal, this matters in practice. Water hardness varies between supplies and between seasons, so measure your own water rather than borrowing a number from a book written for another country.
5. Curing — and why it is not optional
Raw organic material heats up and lowers the surrounding pH as it breaks down, and neither is good for roots. In nature, organic matter decomposes on the surface and works downward. In a container, you have mixed it through the whole root zone at once.
The author’s practice:
- In full sun with no worms in the mix: about two weeks.
- With live worms in the mix: no more than half a day of direct sun, and a correspondingly longer cure.
- His default: about 30 days regardless. His reasoning is that over-curing costs nothing and under-curing causes serious problems.
Everything powdered must be cured in, including blood meal and powdered dolomite lime, which the book treats like an organic material in this respect. All guano and manure must be composted before it goes near a plant.
Verified context on curing time: the book’s curing window comes from experience, and we found no controlled study of cure time for cannabis container soil. The timing of nitrogen release is better established. In a laboratory incubation of seabird guano, fish powder, feather meal and blood meal, 47–60% of the organic nitrogen mineralised within two weeks (Hartz & Johnstone, HortTechnology, 2006, 16(1):39–42). A later paper from the same group put typical release at about 60–80% within 4–8 weeks (Hartz, Smith & Gaskell, HortTechnology, 2010). So a two-week cure in warm conditions has already released roughly half the nitrogen in these meals. That is the point of curing, and also why a tropical cure runs faster.
Verified context on pathogen safety: an ambient cure is not a pathogen-reduction process. The US EPA’s rules (40 CFR Part 503, Appendix B) define composting as a “process to further reduce pathogens” only if the material is held at 55 °C or higher for one of these periods:
- three days in a vessel or aerated static pile
- 15 days in a windrow, turned at least five times
A tumbler of moist soil in the sun does not reliably reach or hold those temperatures. Use manure that the supplier has already hot-composted, or hot-compost it separately before it goes into the recycling bin. The hot-composting article on this forum covers this in detail.
6. Where the worm bin fits
Once the author had a worm bin, he split the work:
- the tumbler handles root balls and coarse plant material
- the worms handle kitchen scraps, trim and finer organics
He treats worm castings as already cured. He does not pre-mix them into stored recycled soil, because they dry out in storage. He adds them about a day before transplanting, at roughly 3 parts soil to 1 part castings when mixing in bulk.
7. Deficiency corrections during the following cycle
These are the book’s troubleshooting suggestions, rewritten and checked where possible:
| Problem | Likely cause | What to do |
|---|---|---|
| Potassium deficiency | The author reports it in hot, dry rooms (not independently verified) | Kelp meal or alfalfa; build enough potassium into the mix at the start |
| Nitrogen deficiency | Microbes use up fast nitrogen, especially blood meal | Fish emulsion or a high-N guano top-dress; feather meal in the mix as prevention |
| Phosphorus deficiency | — | Avoid liquid phosphorus fertilisers: high soluble phosphorus suppresses mycorrhizal colonisation. Use top-dressing and a low-analysis bloom tea. The author believes cannabis stores enough P for about the first four weeks of flower (his own inference, not a measured figure) |
| Sulphur deficiency | Easily mistaken for iron deficiency; the author reports high lights-off temperature as a trigger (not independently verified) | Gypsum as prevention; a short course of Epsom salt foliar spray as an emergency measure |
| Magnesium deficiency | — | Epsom salt or a registered Cal-Mag product, applied lightly and steadily |
| Calcium problems | Usually excess, from hard water or liquid calcium products | Measure your water; cut lime and shell rather than adding more |
| Manganese excess | Groundwater Mn that varies by season | Switch to purer water; especially risky if soil pH is falling |
A correction on molasses: the book presents molasses as a magnesium source with a figure of about 8% Mg. That figure is wrong by more than an order of magnitude. USDA food-composition data list molasses at about 242 mg Mg per 100 g (about 0.24%), and blackstrap is generally in the 0.2–0.5% range. Molasses is not a meaningful magnesium source, so use Epsom salt or a registered Cal-Mag product.
8. On greensand
The book treats greensand (glauconite) as a major potassium source. The agronomic evidence says it releases potassium far too slowly to count as a K source for this cycle. A Rutgers review (Tedrow, Greensand and Greensand Soils of New Jersey: A Review, 2002) found mixed yield results and, overall, very slow potassium release. At most, treat greensand as a long-term mineral reservoir. For more, see the forum’s article Dry Minerals for Living Soil: Greensand, Azomite….
9. Practical sourcing in Southeast Asia
For growers in Thailand and Southeast Asia, where cultivation is legal, the amendments fall into three groups:
- Easy: coco coir (made locally and cheap), rice, gypsum, oyster shell (coastal supply is excellent), kelp/seaweed meal, legume meals, composted manure.
- Available with effort: dolomite lime, Azomite or a similar volcanic rock dust, humic ore, rock phosphate.
- Difficult: blood meal, feather meal, bone meal and consistently graded soft rock phosphate. These are the items most likely to be imported.
Sourcing note: fertilisers made from animal by-products, such as blood, feather and bone meal, are regulated in Thailand. Fertiliser registration goes through the Department of Agriculture, and animal-product imports are controlled by the Department of Livestock Development. Buy registered products, and check the registration number and the label rather than the marketing claims.
If an ingredient is unavailable, substitute by function rather than by name: fast nitrogen, slow nitrogen, calcium, phosphorus, trace minerals, potassium. Some overlap in the recipe is deliberate; for example, calcium comes from several separate sources.
What is your source water TDS, and did you adjust the lime and shell load for it? We often see this adjustment skipped, and skipping it can quietly ruin a recycled batch two or three cycles later. Post your reading and your adjustment.
Related topics on this forum: topic 1091 (no-till), topic 1263 (root disease and when not to recycle), topic 1100 and topic 1343.
This article is technical horticultural information for readers acting legally in their jurisdiction. Cannabis rules differ by country. In Thailand, cannabis flower is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis) B.E. 2568. Cultivation and dispensing are licensed activities, and flower may be dispensed only against a PT 33 prescription. Online sale or advertising of flower is not permitted, and recreational use is not permitted. The Cannabis Control Act is still a draft (Cabinet approved 22 September 2026, sent to the House). Check your local law before growing. Nothing here is legal advice.