Most defoliation advice treats large fan leaves as obstacles. They shade bud sites, block airflow and get removed on a schedule. True Living Organics takes the opposite view: a leaf is a battery the plant will drain when it needs to, and pulling it early throws away nutrients the plant had set aside for flower. The two positions are less opposed than they look. The useful part is seeing which problem each one solves, and which one fits a living-soil pot in a humid Southeast Asian grow room.
Source: The Rev, True Living Organics (Green Candy Press; 2nd edition 2016, 3rd “Druid’s Edition” 2024). This article discusses the book’s pruning guidance and adds our own analysis. It is not a substitute for the book, and details may differ between editions.
1. The leaf-as-battery model
The book’s central observation is that a cannabis plant will pull nutrients, and eventually water, out of its large lower leaves when it wants or needs to. In the second half of flower this becomes routine. The bottom-up yellowing at the end of flower is that process made visible.
Plant physiology supports this. Nitrogen, phosphorus, potassium and magnesium are mobile nutrients. The plant can break down proteins and chlorophyll in older, less productive tissue and move the components to where they are needed. That is why deficiencies of mobile nutrients show first on old growth and deficiencies of immobile nutrients show first on new growth.
The practical inference the book draws: if you remove a leaf before the plant has drained it, the stored material leaves the plant with the leaf.
The rule that follows: do not remove leaves that are only slightly wilted or slightly yellow. A leaf the plant has finished with will be dry and brittle, and will snap off the stem easily. Wait for that.
A useful diagnostic: how much green leaf is left at harvest tells you something about your feeding. Under TLO you may finish with plenty of green leaf, or the plant may have used up its last large leaves, depending on how much core feeding, layering and tea you supplied. That is real feedback on whether your fertility matched the plant’s demand.
2. Where this disagrees with conventional defoliation, and where it does not
Standard defoliation removes healthy green fan leaves at set points, typically around the flip and again in early flower, to get more light to lower bud sites and more air through the canopy. That approach is covered in our Defoliation topic (topic 1209).
The two methods answer different questions:
| Defoliation | TLO pruning | |
|---|---|---|
| Primary aim | Light penetration and airflow in a dense canopy | Keeping stored nutrient in the plant |
| Target tissue | Healthy green fan leaves | Spent, brittle leaves only |
| Timing | Scheduled events | Continuous, as leaves finish |
| Assumes | Nutrient supply is not limiting | Nutrient supply is finite and pot-bound |
The reconciling observation: conventional defoliation is practised where nutrient supply is not the constraint. If you can feed at every irrigation, throwing away a leaf’s stored nitrogen costs nothing you cannot replace tomorrow. A water-only living-soil pot holds a finite amount and there is no bottle to correct with, so the nutrients stored in the leaves are part of the budget.
So the honest conclusion is that neither method is universally right. The correct choice depends on whether your fertility is replaceable. A grower on a bottled 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 and can defoliate moderately without much cost.
This matters more in our region than the book suggests. Many growers here run long-flowering, sativa-leaning cultivars in small tents, often in condos or townhouses where pot size is limited by space and weight. Long flowering in a small water-only pot is where the TLO argument is strongest.
What the evidence says: very few controlled studies exist, and we found none in living soil. The closest is Danziger & Bernstein (2021, Plants 10(9): 1834), who tested eight plant-architecture treatments on large (~2.5 m) medical cannabis plants. The plants were grown in 13 L pots of a peat-based mix in a commercial greenhouse in Israel. Two findings matter here:
- Defoliation three weeks before harvest, and removing branches and leaves from the bottom third of the plant at the switch to short days, did not significantly change inflorescence yield.
- Both treatments let more light into the lower plant, raised cannabinoid levels in the lower buds, and generally made cannabinoid content more uniform.
That study was not living soil, and it did not test the TLO “wait until brittle” approach. It neither confirms nor refutes the battery argument. What it does suggest is that removing low, shaded growth costs little yield, which supports the one structural cut the book insists on.
3. The structural cut the book does insist on
The book is not permissive at all about the bottom of the plant.
Clear everything within at least 20 cm of the soil surface. The lowest branches come off entirely, whether that is two of them or eight. The stated purpose is airflow beneath the canopy.
This is an environmental decision, not a nutrient one. In this region it is the most important line in the chapter. In a humid room, the lower growth is where botrytis and powdery mildew take hold: it is shaded, poorly ventilated, and its bud sites yield little anyway. In Thailand and much of Southeast Asia, treat 20 cm as a minimum rather than a target, especially in the wet season. Airflow and humidity control are covered in more depth in the forum’s existing topics (1145, 1182, 1245, 1254).
Timing, stated clearly:
- The structural cut (the 20 cm clearance and any branch removal) is done once, at the transplant into the flowering pot. The author’s reasoning is that the plant takes two stressors at once but only has to recover once. In his experience it greens back up quickly afterwards.
- Removing dry, brittle, spent leaves is continuous from then until harvest. This is housekeeping, not a pruning event.
4. Topping and main-branch count
The book sizes branch count by HPS lamp wattage. Most growers in the region now use LED, so the table below keeps the book’s HPS figures as the original reference and adds an approximate canopy-area equivalent.
| Book’s reference | Approx. canopy area (our conversion) | Main branches at flowering transplant (author’s range) |
|---|---|---|
| 400 W HPS | roughly 0.8×0.8 m to 1.0×1.0 m | 4–6 (he has also harvested well with 8) |
| 1000 W HPS | roughly 1.2×1.2 m to 1.5×1.5 m | 6–8 |
For LED growers: size by the canopy area you can actually light evenly, not by fixture wattage. LED wattage figures and “HPS-equivalent” claims vary widely between fixtures. Many growers aim for a flowering canopy PPFD in roughly the 600–900 µmol/m²/s range; check the manufacturer’s PPFD map at your hanging height. The area figures above are commonly quoted HPS footprints, not figures from the book.
- 1.2×1.2 m tent: this falls at the boundary between the two rows. Around 6 main branches is a sensible starting point (our extrapolation).
- 0.6×0.6 m tent: this is below anything the book covers. Keep fewer than 4 main branches, or grow untopped (also our extrapolation, untested).
The caveat that is easy to miss: a topped plant only out-yields an untopped one if you also give it more resources, mainly pot size. Topping multiplies the sites competing for a fixed amount of soil fertility and water. Topping without going up a pot size redistributes yield rather than increasing it. Topping technique itself is covered in the forum’s existing topics.
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 to break down slowly. The same material can also go into the worm bin and the soil-recycling bin.
The author adds an important qualifier: he would not do this when growing with mineral nutrients, because the soil would lack a healthy microbial population to process the material. In living soil, dropped leaf becomes a small, continuous mulch and nitrogen input. In an inert or salt-fertilised medium, it is organic matter with nothing to break it down.
A tropical caution not in the book: in a warm, humid room a layer of leaf on the soil surface is also a fungus gnat breeding site and a moisture trap. If gnat numbers are already high, or your room sits above about 70% relative humidity, shred the leaf finer and apply it thinly. Otherwise, send it to the worm bin and keep the pot surface to bark mulch only.
6. What is normal and should not be pruned
Lower-leaf yellowing in flower is the battery being drained: the plant 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 moves unusually fast, the book’s first suspect is overwatering rather than nitrogen deficiency, so check pot weight and watering frequency first.
Water stress showing on lower leaves in flower is a similar adaptive response. The book’s fix is to water slightly more often, not dramatically more.
7. Early nitrogen shortage: the book’s stopgaps
The link to pruning 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 following. These are the author’s own practice, not findings tested in controlled trials:
- Raise the lamp slightly on a plant showing early nitrogen shortage that you plan to transplant within a couple of weeks. His reasoning is that less light means less nitrogen demand, which buys time until the transplant delivers fresh nitrogen through the layering mix and core feed. Under LED, the equivalent would be raising or dimming the fixture. Remember that less light also means less growth.
- Top-dress with a high-nitrogen guano (he describes a product of the NPK 9-3-1 type; this is a product type, not a recommended brand). He reports 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 biology and temperature.
- Or transplant into fresh soil.
- The author’s rule is never to use a liquid nitrogen fertiliser in this system. Treat that as part of the TLO method’s internal logic rather than an established finding.
8. Summary
- Do not remove green or slightly yellow leaves. Wait until they are dry and brittle and snap off cleanly. This removal is continuous through flower.
- Make the structural cut once, at the flowering transplant: clear everything within at least 20 cm of the soil. In a humid climate this is not negotiable.
- Topped plants: about 4–6 (up to 8) main branches under a 400 W HPS-equivalent and 6–8 under 1000 W, as the author’s range. LED growers should size by evenly lit canopy area. Go up a pot size, or topping does not pay.
- Recycle spent leaves onto the mulch in living soil, or into the worm bin. Not onto salt-fertilised media, and only thinly if gnat pressure is high.
- The disagreement with conventional defoliation is about whether your fertility is replaceable, not about whether leaves cast shade. Controlled evidence is thin and does not yet include living soil.
Have you run a living-soil plant with conventional scheduled defoliation against one pruned the TLO way, with the same genetics and the same pot? The theory is clear enough on both sides and there is very little real data. Post your pot volume, your light (LED or HPS, and tent size), whether you were water-only or core-fed, and what happened to yield and to how much green leaf was left at harvest.
Related reading: Defoliation (topic 1209) for the conventional approach.
In Thailand, cannabis 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 Cannabis Control Act is still a draft (Cabinet approved 22/09/2026, sent to the House). Laws differ across Southeast Asia, so check your local law before growing. This article is technical horticultural information, not legal advice.