Croptober Tricks & Treats: Raising Monster Buds
Five under-appreciated techniques, one graveyard of myths, and honest reality checks on each
It’s mid-October, which means two things: outdoor growers across the northern hemisphere are squinting at frost forecasts, and every plant I’ve ever loved looks like a small, sticky, pot-bellied monster. This year I promised myself I’d sort the folklore from the physics of Croptober. Each trick below gets a reality check, because in this hobby “my buddy swears by it” is a citation only in the loosest sense. Grow only where it’s legal for you, and mind your local plant limits.
Trick #1: The Net (SCROG)
Screen of Green means a horizontal net above the plants, with branches woven and tucked through it so the canopy grows flat. The payoff is geometric: every bud site sits at roughly the same distance from the light, which evens out light delivery and improves airflow through the canopy [8]. One guide suggests placing the screen about 20–30 cm above the pot tops and 30–45 cm below the light, and warns that building a proper screen can add up to six weeks of vegetative growth [6]. That guide claims a well-run SCROG can double or triple the yield of an untrained plant [6], and a trellis supplier reports an average 25% yield gain from steel-grid screens [7]. Both are interested parties.
Reality check: the mechanism is sound, but the headline numbers compare a big trained plant to a small untrained one, and per-plant gains aren’t the same as per-square-foot gains. The real win is uniformity, plus the discipline of stripping the shaded growth beneath the net during stretch [7]. The cost is time.
Trick #2: Breathing life into the beast (CO2)
Ambient air has roughly 400 ppm of carbon dioxide. Enrichment guides put the target at 1,200–1,500 ppm during lights-on [9]. The catch is that CO2 only pays when everything else is maxed out. A grow-supply R&D newsletter shows photosynthesis at 400 ppm plateauing at a much lower rate than at 1,500 ppm as light climbs [10], and the enrichment guide notes the technique works best alongside sufficient light and suitable temperatures, and that small growers may struggle to justify the cost [9]. The research lead at a Texas medical cannabis producer reports running 1,000–1,200 ppm [3].
Reality check: if your canopy light is modest, CO2 is money burned. If you’re pushing high intensity, it’s the missing ingredient. And CO2 is an asphyxiant, so run a monitor and never work in a sealed, enriched room.
Trick #3: The Schwazz (leaf stripping)
Schwazzing comes from a grower’s book, Three A Light, whose title promises three pounds per light. The protocol: strip the fan leaves in the first days of flower and again around day 21, so the plant spends its energy on flowers after regrowing the lost foliage [11]. The upside, per the book, is a big jump in yield. The downside, per other growers, is stress: defoliation in flower can reduce yield if done poorly, slow recovery and stretch the flowering period [12].
Reality check: I found grower reports and a popular book, but no peer-reviewed trial. Treat it as high risk and strain-dependent. If you’re curious, try it on one plant or one section of the room, not the whole crop. And note that “back-building”, clipping flower tips mid-flower, targets bag appeal rather than yield, so don’t confuse the two [11].
Trick #4: The Invisible Hand (VPD)
Vapor pressure deficit combines temperature and humidity into one number describing how hard the air pulls water out of the plant. Published ranges for flower disagree: one trade article cites 1.0–1.5 kPa [13], another calls 0.9–1.1 kPa the most favorable zone [14]. My takeaway is that the exact number matters less than holding your chosen target steady, within about 0.05–0.1 kPa according to one grower-focused source, which also notes that too low a VPD slows transpiration and invites fungal trouble [16].
The research warning is sharper. In a 2025 trial, plants grown at very high canopy humidity (78–98%, VPD of 0.25–0.62 kPa) flowered three weeks later and made fewer cannabinoids than plants at 37–58% humidity [15]. That used a CBD-dominant cultivar, so don’t assume the exact magnitude carries over to a THC-heavy strain. Some growers also raise VPD and cool the room in the last two to three weeks to push quality [16].
Reality check: this is the most underrated lever on the list, because it costs little beyond a good sensor and a dehumidifier. It won’t make headlines, but it prevents the failures that do.
Trick #5: The Crypt (dry and cure)
You can grow a monster and bury it in the final ten days. The commercial reference is the “60/60” room, about 60°F and 60% relative humidity, aiming for a final water activity near 0.6. Improperly run drying equipment, one industry columnist argues, causes most of the overdried flower on the market and a staggering loss of terpenes [17]. ASTM’s cannabis committee recommends water activity of 0.55–0.65 for drying and curing [18], and another source says volatile monoterpene loss accelerates below 0.55 (a vendor claim worth verifying) [21].
Slower is better: drying around 60–65°F preserves more terpenes than warmer rooms, and one example recipe runs nine days at 60/60 [19]. For curing, one retailer’s guide suggests sealed containers at 58–62% humidity and 60–70°F, and warns that rehydrating overdried buds is difficult and usually costs quality [20]. Room humidity doesn’t guarantee your flower’s moisture, which is why water-activity meters exist [21][22].
Reality check: this one has the best evidence-to-effort ratio of anything here. It’s free, and it’s the step that decides whether your harvest smells like a candy shop or a hay bale.
The treat: more light, and the graveyard of UV-B
If you only buy one thing, buy light. In a study of intensities from 120 to 1,800 µmol/m²/s, cannabinoid potency did not change with light intensity [1], and a follow-up reported indoor yield rising proportionally with intensity [2]. A commercial research facility saw roughly 1% more yield per 1% more light between 1,000 and 1,800 µmol, with gains plateauing above 1,800 [3]. A fixture-maker’s trial found 26% more light delivered 27% more yield between 1,100 and 1,500, though that vendor has an obvious interest [4]. Bigger buds, same potency per gram: that’s the treat.
And the myth for the graveyard: supplemental UV-B as a potency booster. Two studies found no commercially relevant benefit to yield or cannabinoids, and in one cultivar UV reduced both yield and THC [2][5]. Save your money and your eyes.
Stacking the tricks without summoning a demon
The techniques above aren’t independent, and this is the part most guides skip. What follows is my own analysis of how the cited pieces interact, not a tested protocol. Light, CO2, temperature and VPD are one system: higher intensity raises water demand, which means nutrient and irrigation adjustments [3], and CO2 enrichment only pays once light is high enough to use it [9][10]. If you add CO2 to a room that’s too humid, you’ve bought an expensive way to grow mold, because low VPD slows transpiration and invites fungal trouble [16].
So I’d sequence upgrades like this. First, fix the environment: a sensor you trust, a dehumidifier that can hold your VPD target, and enough airflow to move air through a dense canopy. Second, raise light, which has the strongest evidence and a roughly linear payoff up to about 1,800 µmol [2][3]. Third, flatten the canopy with a net so the extra light actually lands on bud sites instead of wasted fan leaves [8]. Fourth, add CO2 only if you’re running high-intensity light and can monitor it [9][10]. Last, experiment with schwazzing, on one plant, once everything else is stable [12], because a stressed plant in an unstable room tells you nothing about the technique.
One more habit worth stealing from the research crowd: change one variable at a time and keep notes. The Texas facility behind the high-light work says its next studies target how high light interacts with nutrition, temperature and spectrum, because all of these affect yield together [3]. Your closet tent is not a research greenhouse, but the logic scales down fine. If you raise CO2 and swap your light in the same cycle, you’ll never know which one earned the credit, or the blame.
Cheat sheet
|
Trick |
What the evidence says |
Risk |
|---|---|---|
|
Light intensity |
Strong: yield rises with PPFD up to roughly 1,800 |
Low (cost, heat) |
|
Dry and cure |
Strong: moisture and terpene retention are well documented |
Low |
|
VPD control |
Moderate: solid mechanism, ranges disagree |
Low |
|
CO2 enrichment |
Moderate: only pays with high light |
Medium (equipment, safety) |
|
SCROG |
Moderate: mechanism sound, numbers vendor-supplied |
Low (time) |
|
Schwazzing |
Weak: anecdote and one book |
High |
|
UV-B for potency |
Negative: no commercial benefit found |
Wasted money |
Happy haunting, and may your trichomes be cloudy and your jars never grow fur.
Sources
[1] Rodriguez-Morrison V, Llewellyn D, Zheng Y, “Cannabis Yield, Potency, and Leaf Photosynthesis Respond Differently to Increasing Light Levels in an Indoor Environment,” Frontiers in Plant Science, 2021 https://www.frontiersin.org/articles/10.3389/fpls.2021.646020/text
[2] Jones AMP, Zheng Y, “Indoor grown cannabis yield increased proportionally with light intensity, but ultraviolet radiation did not affect yield or cannabinoid concentrations,” Frontiers in Plant Science, 2022 https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.974018/pdf
[3] Cannabis Business Times, “Growing Under High Light Intensities” https://www.cannabisbusinesstimes.com/lighting/led-lighting-cannabis-cultivation-facility/article/15694212
[4] Fluence, High Light Intensity and Cannabis Production (vendor-run trial) https://fluence-led.com/?p=90746
[5] Rodriguez-Morrison V, Llewellyn D, Zheng Y, “Cannabis Inflorescence Yield and Cannabinoid Concentration Are Not Increased With Exposure to Short-Wavelength Ultraviolet-B Radiation,” Frontiers in Plant Science, 2021 https://doaj.org/article/334ea3ceb95d40619207120688d6cad5
[6] Kaya Push, “Screen of Green: Maximizing Your Per Plant Yield” (vendor guide) https://www.kayapush.com/blog/screen-of-green-maximizing-your-per-plant-yield
[7] Growers Network, “Scrogging: Bringing Grow Control” (Canopy Crawler founder; supplier claim) https://growersnetwork.org/cultivation/scrogging-bringing-grow-control/
[8] Hydrobuilder, Trellis Netting & Plant Support for Indoor Growing (retailer) https://hydrobuilder.com/collections/trellis-netting-plant-support
[9] FloraFlex, Using CO2 Enrichment for Improved Cannabis Growth (supplier guide) https://www.floraflex.com/blogs/floraflex-media/using-co2-enrichment-for-improved-cannabis-growth
[10] Hawthorne, R&D Newsletter: Growing Cannabis in High Light Intensity (vendor publication, cites Rodriguez-Morrison et al., 2021 and others) https://www.hawthorne-gardening.com/wp-content/uploads/R_D_Newsletter-High_Light-Yield-Biology_230908aSD.pdf
[11] Leafly, on schwazzing and the book Three A Light https://www.leafly.ca/wp-home/?p=96098
[12] FloraFlex, Marijuana Defoliation Techniques: Enhancing Yield and Bud Quality (supplier guide) https://floraflex.com/blogs/floraflex-media/marijuana-defoliation-techniques-enhancing-yield-and-bud-quality
[13] Cannabis Science and Technology, Understanding VPD and Transpiration Rates for Cannabis Cultivation Operations https://www.cannabissciencetech.com/view/understanding-vpd-and-transpiration-rates-cannabis-cultivation-operations
[14] Cannabis Science and Technology, Intensity and Spectrum: The Role of Lighting in Vapor Pressure Deficit, Aug. 24, 2023 https://cannabissciencetech.com/view/intensity-and-spectrum-the-role-of-lighting-in-vapor-pressure-deficit
[15] Corredor-Perilla IC, Kwon T-H, Park S-H, “Elevated relative humidity significantly decreases cannabinoid concentrations while delaying flowering development in Cannabis sativa L.,” Frontiers in Plant Science, 2025 https://public-pages-files-2025.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2025.1678142/text
[16] GrowMag, VPD discussion (Grubbycup) https://growmag.com/?p=8113
[17] Cannabis Business Times, Newer Cannabis Drying and Curing Methods to Achieve Superior Quality https://www.cannabisbusinesstimes.com/columns/tomorrow-in-cannabis/news/15829242/newer-cannabis-drying-and-curing-methods-to-achieve-superior-quality
[18] Doctor Greenhouse, Drying Cannabis: Is There a Science Behind the Art? https://www.doctorgreenhouse.com/blog/drying-cannabis-is-there-a-science-behind-the-art
[19] Ed Rosenthal, Cannabis Drying and Curing: How to Preserve Terpenes, Smoothness, and Potency, Jan. 2026 https://www.edrosenthal.com/ask-ed-blog/2026/1/21/cannabis-drying-and-curing-how-to-preserve-terpenes-smoothness-and-potency
[20] Happy Hydro, Best way to cure weed for maximum potency and flavor (retailer guide) https://happyhydro.com/blogs/growing-cannabis/best-way-to-cure-weed-maximum-potency-flavor
[21] Cannatrol, What Is Water Activity (aW) in Cannabis and Why Does It Matter? (vendor) https://cannatrols.com/blogs/news/what-is-water-activity
[22] Aroya, Best practices for drying and curing cannabis https://aroya.io/education-guides/best-practices-drying-curing-cannabis
CROPTOBER NEWS, READ ON…
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