Source: the book True Living Organics by The Rev (Green Candy Press; 2nd edition 2016, 3rd “Druid’s Edition” 2024). “The Rev” is the pen name of the book’s author. This article explains the book’s pruning advice and adds editorial analysis. It does not replace the book, and details may differ between editions.
Most advice on removing leaves treats the large fan leaves of a cannabis plant as a problem. They shade the lower buds and block airflow, so growers strip them on a fixed schedule. The book True Living Organics takes the opposite view. A large leaf holds nutrients that the plant moves out again when the flowers need them, so pulling the leaf early throws those nutrients away. This article sets out both approaches, the problem each one solves, and how to choose for a living-soil pot in a humid grow room in Thailand or Southeast Asia.
Two terms first. True Living Organics (TLO) is an organic growing method. All the fertility is built into the soil before planting, and the plant then gets mostly plain water. Living soil is soil with an active population of microbes, fungi and small soil animals. They break down organic matter and release nutrients to the roots.
1. Large leaves as a nutrient store
The book’s central observation is simple. A cannabis plant pulls nutrients, and later water, out of its large lower leaves when it wants or needs them. In the second half of flowering this becomes routine. The yellowing that climbs from the bottom of the plant near the end of flowering is this process made visible.
Plant physiology supports the idea. Nitrogen, phosphorus, potassium and magnesium are mobile nutrients, meaning the plant can move them from one part to another. It breaks down proteins and chlorophyll (the green pigment) in older, less productive leaves. It then sends the components to where they are needed. That is why a shortage of a mobile nutrient shows first on old leaves. A shortage of an immobile nutrient, one the plant cannot move, shows first on new growth.
What the book concludes: if you remove a leaf before the plant has emptied it, the nutrients stored in that leaf leave the plant with it.
The rule that follows: do not remove leaves that are only slightly wilted or slightly yellow. A leaf the plant has finished with is dry and brittle, and snaps off the stem easily. Wait until it reaches that state.
What the leaves tell you about feeding: the amount of green leaf left at harvest is feedback on your soil. Under TLO you may finish with plenty of green leaf. Or the plant may have used up its last large leaves. The result depends on how much extra feeding you gave during the grow:
- Core feeding: burying dry organic fertiliser in holes made in the soil, so roots meet it as they grow.
- Layering: placing a richer, amended soil layer in the lower part of the pot at transplant, which the roots reach later.
- Tea: a liquid made by steeping compost or other organic materials in water, then pouring it onto the soil.
How much green leaf remains shows whether your soil supplied what the plant demanded.
What to do: from mid-flowering, pick off only leaves that come away with a light touch. At harvest, photograph the plant and note in your grow log how much green leaf is left, next to what you fed. Over two or three crops, these notes show whether your soil gave the plant too little, enough or more than it used.
2. Where TLO pruning disagrees with ordinary defoliation, and where it does not
Ordinary defoliation removes healthy green fan leaves at set points. The usual times are around the switch to flowering (the “flip”, when the light schedule changes to 12 hours on and 12 hours off) and again in early flowering. The aim is more light on the lower bud sites and more air through the canopy, the layer of leaves and buds at the top of the plants.
The two methods answer different questions:
| Ordinary defoliation | TLO pruning | |
|---|---|---|
| Main aim | Light and airflow in a dense canopy | Keeping stored nutrients in the plant |
| Which leaves | Healthy green fan leaves | Spent, dry, brittle leaves only |
| Timing | Fixed events | Continuous, as each leaf finishes |
| Assumes | Nutrient supply is not limited | Nutrient supply is fixed by what is in the pot |
Why both can be right: ordinary defoliation is practised where nutrients are not the limit. If you give liquid nutrients at every watering, the nitrogen lost with a leaf is replaced at the next watering. A water-only living-soil pot holds a fixed amount of nutrients. There is no liquid feed to make up a shortfall. So the nutrients stored in the leaves are part of what the plant has to finish the crop with.
The fair conclusion is that neither method is right everywhere. The right choice depends on whether you can replace the nutrients the plant loses.
- A grower on a bottled nutrient programme with a dense canopy has a real case for defoliation.
- A grower with a small water-only living-soil pot and a long flowering time has a real case for the TLO approach.
- A grower with living soil in a large pot and generous core feeding sits in between. This grower can defoliate moderately without losing much.
Translator’s note: this choice matters more in Thailand and Southeast Asia than the book suggests. Many growers here run long-flowering, sativa-leaning cultivars in small tents. Often the tent is in a condo or townhouse, where space and floor weight limit pot size. Long flowering in a small water-only pot is exactly where the TLO argument is strongest.
What the research says: very few controlled studies exist, and none could be found in living soil. The closest is a 2021 study by Danziger and Bernstein, published in the journal Plants. They tested eight ways of shaping the plant on large medical cannabis plants, about 2.5 m tall. The plants grew in 13-litre pots of a peat-based mix in a commercial greenhouse in Israel. Two findings matter here:
- Two treatments did not significantly change flower yield: removing leaves three weeks before harvest, and removing the branches and leaves from the bottom third of the plant at the switch to short days.
- Both treatments let more light into the lower plant, and the authors report that this raised cannabinoid levels locally. Removing leaves also made cannabinoid content more even across the plant. Removing the bottom third alone did not.
That study did not use living soil. It also did not test the TLO rule of waiting until a leaf is brittle. So it neither confirms nor disproves the nutrient-store argument. What it does suggest is that removing low, shaded growth costs little yield. That supports the one structural cut the book insists on (section 3).
What to do: write down three facts about your setup: pot volume, whether you give liquid nutrients at most waterings, and the expected flowering length of your cultivar. If you feed at every watering and the canopy is dense, scheduled defoliation is a reasonable choice. If you grow water-only in a small pot with a long flowering time, follow the TLO rule. If you are in between, remove fewer leaves than a full scheduled defoliation would.
3. The structural cut the book insists on
The book is strict about the bottom of the plant.
Clear everything within at least 20 cm of the soil surface. The lowest branches come off completely, whether that is two branches or eight. The stated purpose is airflow under the canopy.
This is a decision about the room’s air, not about nutrients.
Translator’s note: for growers in this region, this is the most important advice in the chapter. In a humid room, the lower growth is where botrytis (grey mould, also called bud rot) and powdery mildew take hold. That growth is shaded and poorly ventilated, and its bud sites give little yield anyway. In Thailand and much of Southeast Asia, treat 20 cm as a minimum, not a target, especially in the rainy season. Humidity control and airflow in the grow room are covered in a separate topic.
When to do each job:
- The structural cut, meaning the 20 cm clearance and any branch removal, is done once, at the transplant into the flowering pot. The book’s author reasons that the plant takes two stresses at once but only has to recover once. In his experience, the plant turns green again quickly afterwards.
- Removing dry, brittle, spent leaves is continuous from then until harvest. It is routine cleaning, not a pruning event.
What to do: on the day you move the plant into its flowering pot, measure 20 cm up from the soil with a ruler. Remove every branch and leaf below that line. In the rainy season, or if the lower canopy stays damp, set the line higher. After that, pick off only dry, brittle leaves each time you water.
4. Topping and the number of main branches
Topping means cutting off the main growing tip so the plant grows several main branches instead of one. The book sets the number of main branches by the wattage of an HPS lamp (high-pressure sodium, the older orange-light type of grow lamp). Most growers in the region now use LED lights, so the table keeps the book’s HPS figures as the reference. The editor has added an approximate canopy area for each.
| Book’s reference | Approx. canopy area (editor’s conversion, not from the book) | Main branches at the flowering transplant (book’s range) |
|---|---|---|
| 400 W HPS | about 0.8×0.8 m to 1.0×1.0 m | 4–6 (the author has also harvested well with 8) |
| 1000 W HPS | about 1.2×1.2 m to 1.5×1.5 m | 6–8 |
The area figures are commonly quoted footprints for HPS lamps, not figures from the book.
For LED growers: size the plant by the canopy area your light covers evenly, not by the fixture’s wattage. LED wattage figures and “HPS-equivalent” claims vary widely between fixtures. A better measure is PPFD: the amount of light plants can use that reaches each square metre of canopy every second, in µmol/m²/s. Many growers aim for roughly 600–900 µmol/m²/s across a flowering canopy. Check the manufacturer’s PPFD map at the height you hang the light.
Two common tent sizes, extrapolated by the editor rather than taken from the book:
- 1.2×1.2 m tent: this sits at the boundary between the two rows. About 6 main branches is a sensible starting point.
- 0.6×0.6 m tent: this is smaller than anything the book covers. Keep fewer than 4 main branches, or do not top at all. This has not been tested.
The condition that is easy to miss: a topped plant only out-yields an untopped one if you also give it more resources, mainly a bigger pot. Topping multiplies the bud sites competing for the same soil nutrients and water. Without a bigger pot, topping spreads the same yield over more sites instead of increasing it. Topping technique is covered in a separate topic.
Translator’s note: in a condo or townhouse, the largest pot you can fit, carry and drain safely sets the limit, not the light. If you cannot go up a pot size, topping is unlikely to pay.
What to do: before you top, decide the flowering pot size you can actually fit and move. If it is no bigger than the current pot, keep fewer main branches or grow the plant untopped.
5. Recycling the leaves
Spent leaves are not waste. The book’s method is to shred, chop or tear them and scatter them over the mulch layer, where they break down slowly. Mulch is a cover of bark, straw or plant material on the soil surface. The same leaves can also go into a worm bin or into the bin where you recycle old soil.
The book’s author adds an important limit: he would not do this when growing with mineral nutrients. Soil fed with mineral salts lacks a healthy microbial population to break the leaves down. In living soil, fallen leaf becomes a small, steady supply of mulch and nitrogen. In an inert medium, or one fed with mineral salts, it is organic matter with nothing to break it down.
Translator’s note: this caution is not in the book. In a warm, humid room, a layer of leaves on the soil surface also traps moisture and gives fungus gnats a place to breed. Fungus gnats are small black flies whose larvae live in damp topsoil.
What to do: if gnat numbers are already high, or your room sits above about 70% relative humidity, shred the leaves finer and spread them thinly. If neither applies but you still see gnats, send the leaves to the worm bin and keep only bark mulch on the pot.
6. What is normal and should not be pruned
Yellowing of the lower leaves in flowering is the plant drawing down its stored nutrients. It is moving nitrogen to the top of the canopy. The book’s advice is to do nothing beyond picking off fully dead leaves.
If the yellowing spreads unusually fast, the book’s first suspect is overwatering, not nitrogen shortage. So check how heavy the pot is and how often you water before you change anything else.
Signs of water stress on the lower leaves in flowering are a similar adjustment by the plant. The book’s fix is to water slightly more often, not dramatically more.
Translator’s note: in Thai heat of 30–35 °C, a pot can dry much faster on a hot day than on a cool, rainy one. Your watering timetable from last month may no longer fit.
What to do: lift each pot before you water, at the same time of day, and note whether it feels heavy or light. If lower leaves yellow fast while the pot still feels heavy, water less often. If they droop while the pot feels light, water a little more often.
7. Early nitrogen shortage: the book’s short-term fixes
The pruning rule comes first: if a plant is short of nitrogen, do not strip its lower leaves. Those leaves are the reserve it is drawing on. Remove only what is fully dry and brittle.
Beyond that, the book offers the steps below. These are the author’s own practice, not findings tested in controlled trials:
- Raise the lamp slightly if a plant shows early nitrogen shortage and you plan to transplant it within a couple of weeks. His reasoning is that less light means less demand for nitrogen. That buys time until the transplant gives the roots fresh nitrogen from the layering mix and the core feed. Under LED, the same step means raising or dimming the light. Less light also means less growth.
- Top-dress with a high-nitrogen guano, meaning sprinkle it on the soil surface. Guano is dried bat or seabird droppings sold as organic fertiliser. He describes a product with an NPK ratio of the 9-3-1 type (the three label numbers for nitrogen, phosphorus and potassium). This is a product type, not a recommended brand. He reports that it greens the plant up in about 7–10 days. That is his observation, not a measured response time, and it will vary with soil life and temperature.
- Or transplant into fresh soil.
- Never use a liquid nitrogen fertiliser in this system. That is the author’s rule. Treat it as part of the TLO method’s own logic, not as an established finding.
Translator’s note: before buying guano or any other fertiliser in Thailand, check that the product is legally registered and labelled (how to check a fertiliser’s legal status). To find a suitable high-nitrogen guano, ask a licensed fertiliser seller in Thailand or ask other growers in the General Nutrients Q&A board. How quickly different organic nitrogen sources release their nitrogen is covered in a separate topic.
What to do: when lower leaves yellow early in a plant short of nitrogen, leave them on. Then choose one fix: raise or dim the light until the transplant, top-dress with guano, or move the plant into fresh soil. Note the date and watch whether new growth greens up over the next 7–10 days.
8. Summary
- Do not remove green or slightly yellow leaves. Wait until they are dry and brittle and snap off cleanly. Keep doing this throughout flowering.
- Make the structural cut once, at the flowering transplant: clear everything within at least 20 cm of the soil. In a humid climate, do not skip this step.
- Topped plants: about 4–6 main branches (up to 8) under a 400 W HPS or its equivalent, and 6–8 under a 1000 W HPS, as the book’s range. LED growers should size by the canopy area the light covers evenly. Move up a pot size, or topping does not pay.
- Recycle spent leaves onto the mulch in living soil, or into the worm bin. Do not put them on media fed with mineral salts, and spread them only thinly if gnats are a problem.
- The disagreement with ordinary defoliation is about whether you can replace lost nutrients, not about whether leaves cast shade. Controlled evidence is thin and does not yet include living soil.
Share your results
Very little real data exists on this question, although the reasoning on both sides is clear. If you have grown two living-soil plants of the same genetics in the same pot size, one with scheduled defoliation and one pruned the TLO way, post your results below. Include your pot volume, your light (LED or HPS, and tent size), whether you grew water-only or used core feeding, and what happened to yield and to the amount of green leaf left at harvest.
References
- The Rev. True Living Organics. Green Candy Press; 2nd edition 2016, 3rd “Druid’s Edition” 2024.
- Danziger, N. & Bernstein, N. (2021). Plants 10(9): 1834.
In Thailand, cannabis flower is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568, and cultivation requires the applicable notification or licence. The draft Cannabis Control Act is not yet law: the Cabinet approved the draft on 22 September 2026 and sent it to the House. Laws differ across Southeast Asia, so check your local law before growing. This article is technical horticultural information, not legal advice.