The R05 Claim Ledger, in Plain English

Companion to: ledger.md (the technical version) · Updated August 28, 2026 (citation links added) What this is: Every claim from the R05 research, explained the way you’d explain it to a friend. The claim IDs match the technical ledger, so anything here can be traced back to its evidence — and the Sources line under each claim links straight to the actual studies.

How to read the confidence labels:

• ✅ Solid — multiple good studies agree; scientific consensus
• 👍 Probably true — real evidence supports it, but not enough studies yet to call it settled
• 🌱 Grower wisdom — widely practiced and believed, but science hasn’t formally tested it
• ❓ Honestly unknown — nobody has good data; anyone claiming certainty is guessing

Energy & carbon

C001 ✅ — Growing cannabis in a warehouse produces a LOT of carbon. The best study modeled it at roughly 2,300–5,200 kg of CO2 for every kilogram of dried flower — and the biggest factor isn’t the grower’s skill, it’s where the building is. A warehouse in hydro-powered Washington pollutes less than half as much as one running on a coal-heavy grid with brutal AC bills. Sources: Summers et al. 2021, Nature Sustainability

C002 ✅ — Indoor beats outdoor on almost everything except the planet. Every serious study points the same direction: growing under the sun uses dramatically less energy than growing under electric lights in a climate-controlled box. How much less depends on location, but the direction never flips. Sources: Summers et al. 2021 · Desaulniers Brousseau et al. 2024 (outdoor LCA) · Desaulniers Brousseau et al. 2024 (“Greener green”) · Mills 2025, One Earth

C003 👍 — Outdoor growing cuts carbon by roughly 90%. A Canadian study modeled outdoor cultivation at about a tenth of indoor’s climate impact. The exact number varies by study, but “sunlight is free” turns out to be true for the atmosphere too. Sources: “Greener green,” Resources, Conservation & Recycling 2024 · Outdoor LCA, ACS Ag. Sci. & Tech. 2024

C004 ✅ — LED lights help a lot, but they don’t fix indoor’s energy problem. Modern LEDs use way less electricity than the old orange HPS lamps (measured: about 50% more light per unit of energy). But lights are only part of the bill — real-world measurements found air conditioning and dehumidification eating ~45% of a facility’s energy. Swapping the bulbs doesn’t turn a warehouse into a meadow. Sources: Westmoreland, Kusuma & Bugbee 2021, PLOS ONE · PG&E/ETCC field study 2022–24 · Summers et al. 2021

C005 👍 — Ironically, switching to LEDs can raise your heating bill. Old HPS lamps doubled as space heaters. Take them out in a cold climate and the furnace has to make up the difference. Sources: PG&E/ETCC field study

C006 👍 — What eats the most energy depends on your climate. Hot and humid? Dehumidification dominates. Cold winters? Heating dominates. There’s no single “indoor energy bill” — it’s geography. Sources: npj Sustainable Agriculture 2025 · “Greener green” 2024

C007 👍 — Sealed grow rooms can recapture most of their water. Plants “sweat” out most of the water you give them. In a sealed room, that moisture condenses on the AC coils — one field study measured ~70% of the water coming back as recoverable condensate. Outdoor plants release that water to the sky. Sources: PG&E/ETCC field study

C008 ✅ — “Greenhouse” isn’t one thing — it’s a whole ladder. A simple plastic hoop house is nearly outdoor growing. A sealed glass palace with LED arrays, chillers, and CO2 injection is nearly a warehouse with windows. California’s own licensing system splits them into tiers. Lumping them together produces nonsense averages. Sources: CA Dept. of Cannabis Control license types · Collado et al. 2024, Frontiers in Plant Science

C009 ❓ — Nobody has actually measured the carbon footprint of each greenhouse type. It’s probably a ladder — passive hoop house lowest, sealed high-tech highest — but the specific numbers you may see online are extrapolations, not measurements. This is a genuine hole in the science. Sources: documented as a data gap by both research passes — no study to link is the point.

C010 👍 — The whole US cannabis industry emits like millions of cars. A 2025 analysis modeled ~44 million tonnes of CO2 per year, mostly from indoor growing, and estimated that shifting cultivation outdoors could cut emissions by up to ~76%. It’s a model, not a census — but the scale is striking. Sources: Mills 2025, One Earth

Beyond carbon

C011 ✅ — “Outdoor” doesn’t automatically mean “sustainable.” Low energy use is only part of the story. Where your water comes from and when, what your soil came in, fertilizer runoff, and where the farm sits all matter — and can matter a lot. Sources: Outdoor LCA 2024 · Bauer et al. 2015, PLOS ONE · Dillis et al. 2019

C012 👍 — The bags of soil might be the dirtiest part of an outdoor grow. In the one outdoor life-cycle study with field data, potting media — the bagged soil mix — accounted for up to 75% of the operation’s climate impact. If you buy new soil every season, that’s your footprint. (This is exactly why soil reuse and living-soil methods matter — coming in later reports.) Sources: Desaulniers Brousseau et al. 2024, ACS Ag. Sci. & Tech.

C013 ✅ — The water problem is about timing, not thirst. Cannabis isn’t an unusually thirsty crop. The trouble is that its peak watering season lands exactly when California’s streams are at their lowest — and pulling water then can genuinely hurt salmon habitat. The fix is boring and effective: store water in the rainy season. Sources: Bauer et al. 2015, PLOS ONE · Dillis et al. 2019

C014 ✅ — That famous “22.7 liters per plant per day” number? It’s a guess. It came from a 2010 county ordinance, not a measurement, picked from estimates ranging from 4 to 57 liters. Nobody has nailed down a reliable per-plant water figure. Treat any precise-sounding water stat with suspicion. Sources: Bauer et al. 2015 (see Methods)

C015 👍 — More light can mean more water used but less water per gram. A greenhouse study found extra lighting made plants drink more overall while producing so much more flower that water-per-gram dropped ~37%. “Efficient” and “low-use” aren’t the same thing. Sources: Collado, Hwang & Hernández 2024, Frontiers in Plant Science

C016 👍 — Glowing greenhouses at night are a real problem. Unshielded greenhouse lights create serious light pollution. California actually requires cultivation lights to be shielded from sunset to sunrise. Sources: CA DCC cultivation regulations

C017 ✅ — The scary pesticide-contamination stories come from illegal grows. Trespass grows on public land have left genuinely nasty chemical residues. But that’s a lawlessness problem, not an “outdoor cannabis” problem — it doesn’t describe licensed farms. Sources: Science of the Total Environment 2025 (trespass grows) · Water Quality Research Journal 2022

Quality

C018 👍 — Where you grow really does change the plant’s chemistry. Genetically identical clones grown indoor vs. outdoor came out chemically different. The environment matters. What exactly it does — that’s where it gets murky. Sources: Zandkarimi et al. 2023, Molecules

C019 👍 — In the one head-to-head study, sun-grown flower was more chemically interesting. Same clones, grown both ways: the outdoor plants had more terpenes and more kinds of terpenes (the spicy/woody sesquiterpene family especially), plus rare cannabinoids the indoor plants didn’t make. The indoor flower had more degraded, oxidized compounds. THC levels? Basically the same. Big caveat: it’s ONE study, two strains, and the outdoor plants also got living soil — so we can’t cleanly credit the sunshine. Sources: Zandkarimi et al. 2023, Molecules

C020 ❓ — “Indoor weed is stronger” has never actually been proven. No study has shown that a roof and electric lights inherently produce more THC once you account for genetics, grower skill, and harvest timing. Indoor flower often tests higher at the shop — but that’s selection and marketing, not demonstrated biology. Sources: Zandkarimi et al. 2023 · Australian ACT home-grow study

C021 ❓ — “Sun-grown always has better terpenes” isn’t proven either. One promising study points that direction (see C019), but one small study can’t carry “always.” Both fan bases are ahead of the science. Sources: Zandkarimi et al. 2023 — and the absence of anything else is the point.

C022 🌱 — The indoor price premium is real — and it measures belief, not chemistry. Indoor flower reliably sells for more. That premium reflects looks, density, THC-number shopping, and habit. Nobody has run blind taste/quality tests with matched genetics. Until someone does, the premium is a market custom, not a lab result. Sources: Cannabis Business Times 2021 industry report (PDF) · MJBiz Factbook 2018 (print)

C023 ❓ — No growing style is automatically “cleaner.” Outdoor faces windborne spores and pesticide drift; indoor breeds its own problems — mold in humid pockets, viroids spreading through recirculating systems, and illegal indoor grows have tested full of pesticides too. There’s no fair apples-to-apples contamination data across states, because every state tests differently. Sources: Cuypers et al. 2017 (pesticides in illicit indoor grows) · Green et al. (outdoor microbial hazards) · Clinical Therapeutics 2026 (state testing inconsistency)

C024 👍 — Heavy metals come from what the plant grows in, not whether it’s inside. Cannabis is unusually good at sucking metals out of soil and water. Grow in clean media with clean inputs and it’s a non-issue; grow in ground with an industrial past and it isn’t — roof or no roof. Sources: broad phytoremediation literature — see the technical ledger (C024) for grading detail.

Yield, money & risk

C025 ✅ — Light deprivation works by faking longer nights. Cannabis flowers when nights get long. Pull blackout curtains over a greenhouse every evening in June and the plants think it’s autumn — so you can harvest multiple times a year instead of once. How many times depends on your climate, setup, and strain; 2–4 is typical. (The old “up to 5×” claim was optimistic.) Sources: CA DCC light-dep definition · standard photoperiodism literature

C026 ✅ — Yield comparisons are usually apples vs. orchards. Per plant? Outdoor wins — plants can become trees. Per square foot per year? Indoor wins — dense plants, multiple harvests. Anyone quoting a yield comparison without saying per what is telling you nothing. Sources: Backer et al. 2019 yield meta-analysis, Frontiers in Plant Science

C027 👍 — Outdoor is cheapest to produce, indoor most expensive — but the numbers age fast. Industry surveys consistently found the same ranking (2021 medians: ~$214/lb outdoor, $256 greenhouse, $472 indoor). The order is durable; the dollar figures depend on your state, your power rates, your taxes, and the year. Sources: Cannabis Business Times 2021 report (PDF)

C028 👍 — More harvests doesn’t mean more profit. A 2026 New York greenhouse study found the same facility lost money growing quick autoflowers but made money growing slower photoperiod plants — at the same selling price. The spreadsheet matters more than the calendar. Sources: Vergara & Ruterbories 2026, Journal of Cannabis Research

C029 👍 — When prices crash, indoor growers bleed first. High-cost warehouse production has the thinnest margins. When wholesale prices drop, cheap outdoor and light-dep farms survive prices that bankrupt indoor operations. Sources: CBT 2021 cost data · Vergara & Ruterbories 2026

C030 🌱 — Every system has its own nightmare. Outdoor growers fear October rain, frost, and wildfire smoke. Light-dep growers fear a torn curtain — one light leak during the dark period can turn a crop hermaphrodite. Indoor growers fear the power outage that cooks a sealed room in hours. Pick your poison; there’s no risk-free way to farm. Sources: practitioner consensus (that’s what 🌱 means — no formal study exists, and we say so).

The big picture

C031 ❓ — Nobody actually knows how much cannabis is grown each way. We have license counts and licensed acreage, but licenses aren’t production. Any confident “X% of cannabis is grown indoors” statistic is made up. Sources: what exists: CA DCC licensing data · Health Canada cannabis market data — neither converts to production share.

C032 ✅ — The measuring stick changes the winner. Per plant, per square meter, per year, per kilogram — different units crown different champions. Always ask “per what?” Sources: Backer et al. 2019 · Summers et al. 2021 (functional-unit discussion)

C033 ✅ — Old statistics don’t age well here. The most-quoted cannabis carbon number comes from a 2012 study built on obsolete lights and a dirtier power grid. Different studies also count different things (just electricity? the building? the fertilizer?). You can’t average them into one number — and you shouldn’t trust anyone who does. Sources: Mills 2012, Energy Policy (the vintage baseline) · Mills 2025, One Earth (the modern update, same author)

Every paragraph above is a translation of a formally graded claim — the full grading, caveats, and verification history live in ledger.md and SOURCE_LIBRARY.md.