Horus Grow Library
Learn to grow, from one tent to a licensed facility.
A visual, source-backed library of cannabis cultivation. Real numbers, decision rules, worked examples and the way things go wrong, written by growers for adults where growing is legal.
- Articles
- 50
- Sections live
- 25/25
- Figures
- 95
Start here
Your first home grow
From checking the law to a cured first harvest, in the order a first-timer needs it.
- 01Law and responsible growing by countryWhere growing is legal, the limits that apply, and where to check the current rules.
- 02Fundamentals and plant biologyHow the plant works, and what that means for every decision you make.
- 03Grow spaces and facility designTents, rooms, greenhouses, outdoor plots and commercial facility design.
- 04LightingPPFD, DLI, spectrum, efficacy and fixture layout, from one tent to multi-tier rooms.
- 05Climate and environmentTemperature, humidity, VPD, airflow, CO₂ and HVAC, and how they interact.
- 06Growing media and containersSoil, coco, rockwool and containers, and how each changes watering and feeding.
- 07Water and irrigationWater quality, watering, irrigation systems and crop steering.
- 08NutritionWhat the plant takes up, in what ratios and when, and how to build a feed programme.
- 09Growth stages week by weekWeek by week: the targets and checks for each stage of the crop.
- 10Harvest, drying and curingHarvest timing, trimming, drying and curing without losing quality.
Diagnose a problem
Start from what you can see, rank the likely causes and test the cheapest first.
- 01TroubleshootingStart from the symptom: ranked causes, a test for each, the fix.
- 02Deficiencies and toxicitiesIdentify deficiencies and toxicities from where and how the symptoms appear.
- 03PestsMites, thrips, aphids, gnats and more: identify, monitor and control.
- 04DiseasesMildews, moulds, root rots, viroids and abiotic disorders.
- 05IPM programmesPrevention, scouting, thresholds and biological control programmes.
Plan a licensed facility
Licensing, facility design, climate at scale and the quality systems auditors expect.
- 01Law and responsible growing by countryWhere growing is legal, the limits that apply, and where to check the current rules.
- 02Commercial operationsPlanning, operations, energy and scaling a licensed cultivation site.
- 03Grow spaces and facility designTents, rooms, greenhouses, outdoor plots and commercial facility design.
- 04Climate and environmentTemperature, humidity, VPD, airflow, CO₂ and HVAC, and how they interact.
- 05Quality, testing and standardsLab testing, standards such as GACP, and quality control.
Run an association
Cultivation planning, records and compliance for a non-profit club.
- 01Law and responsible growing by countryWhere growing is legal, the limits that apply, and where to check the current rules.
- 02Cannabis clubs and associationsRunning cultivation for a non-profit association: governance, planning and records.
- 03Commercial operationsPlanning, operations, energy and scaling a licensed cultivation site.
- 04Quality, testing and standardsLab testing, standards such as GACP, and quality control.
Featured and recently updated
Cooling load calculator: sizing AC to lighting and transpirationIn a sealed room every watt you plug in becomes heat to remove; transpiration decides how much of it arrives as moisture. Size to both, then convert to TR.VPD calculator: leaf vapour pressure deficit from temperature and humidityEnter air temperature, RH and a leaf-to-air offset to get leaf VPD in kPa, checked against propagation, veg and flower targets.Redundancy: what happens when a unit fails in week 7 of flowerWhat actually happens to room RH when a dehumidification unit fails in dense late flower, modelled minute by minute, and how much redundancy the risk justifies.Common compliance failures in cannabis associations, and what actually triggers themRanked by evidence strength: Uruguay's inspection data, Malta's reconciliation clause, and Spain's proof a club can fail with no operator error at all.The cost structure of a licensed cannabis cultivation siteCapex builds the room; opex runs it, and labour and energy usually dominate running costs. A worked 500 m² example shows where the money goes.HLVd prevalence: what's actually been measured, at what sample sizeThe HLVd infection-rate figure everyone cites traces to one company's client data, not a survey. What's actually been measured, and what to do anyway.
Every section
Foundations
2 / 40Fundamentals and plant biologyHow the plant works, and what that means for every decision you make.2 / 50Law and responsible growing by countryWhere growing is legal, the limits that apply, and where to check the current rules.2 / 45Genetics, seeds and clonesSeeds, clones, mother plants, breeding, selection and clean stock.
The grow space
2 / 45Grow spaces and facility designTents, rooms, greenhouses, outdoor plots and commercial facility design.2 / 50LightingPPFD, DLI, spectrum, efficacy and fixture layout, from one tent to multi-tier rooms.2 / 50Climate and environmentTemperature, humidity, VPD, airflow, CO₂ and HVAC, and how they interact.2 / 80Equipment comparisonsLights, climate kit, meters and post-harvest tools compared by criteria, never by brand.
Water and feeding
2 / 30Growing media and containersSoil, coco, rockwool and containers, and how each changes watering and feeding.2 / 40Water and irrigationWater quality, watering, irrigation systems and crop steering.2 / 40NutritionWhat the plant takes up, in what ratios and when, and how to build a feed programme.
Plant health
2 / 55Deficiencies and toxicitiesIdentify deficiencies and toxicities from where and how the symptoms appear.2 / 55PestsMites, thrips, aphids, gnats and more: identify, monitor and control.2 / 50DiseasesMildews, moulds, root rots, viroids and abiotic disorders.2 / 25IPM programmesPrevention, scouting, thresholds and biological control programmes.2 / 50TroubleshootingStart from the symptom: ranked causes, a test for each, the fix.