Grower reference library

Short, factual references — the same numbers our grow journal grades real grows against. No login, no paywall.

• VPD, temperature & humidity targets by growth stage
• Autoflower care & feeding by week
• Nutrient deficiency chart (N/P/K/Ca/Mg/Fe)
• pH by growing medium
• Drying & curing targets
• VPD calculator
• DLI calculator — PPFD to daily light integral
• When to harvest: trichome guide
• Light schedules (18/6, 12/12, autos)
• Training methods: LST, topping, SCROG
• Strains with full data (1,191 with photo, flowering time, type & lineage)
• Full strain A–Z (20,726 strains)
• Cannabis breeder library

Guides

• Automatic VPD Monitoring: Which Sensors Work and What They Cost — A VPD chart tells you the target. A sensor tells you whether you hit it at 3am. What to buy, cloud versus local trade-offs, and how to get VPD logged without doing arithmetic.
• Brown or Rust Spots on Cannabis Leaves: Calcium, pH or Pests? — Rust-coloured speckles have several causes that look alike. Where the spots sit, how they are shaped, and what the runoff pH reads will tell you which one you have.
• Bud Rot (Botrytis): Catching It Before It Takes the Harvest — Grey mould works from the inside out, so by the time you see it the damage is done. What to check, why lights-off humidity is the real culprit, and why affected bud cannot be saved.
• Drooping Cannabis Leaves: Overwatered or Underwatered? — Both look like drooping, and the wrong fix makes it worse. Tell them apart by leaf feel and pot weight in under a minute, then fix the root cause instead of the symptom.
• Fungus Gnats: Small Flies in Your Grow and the Larvae That Matter — The adults are an annoyance; the larvae in the medium are the actual damage. Why letting the top layer dry out does more than any spray.
• Heat Stress in Cannabis: Taco Leaves, Foxtails and What to Fix First — Upward-curling leaf edges mean the plant is defending itself against water loss. What temperature is actually too hot, why humidity changes the answer, and the cheapest fixes that work.
• Hermies and Nanners: Why Plants Turn and What to Do About Seeds — Bananas and pollen sacs in flower mean stress or genetics. How to tell the two apart, whether the crop is still worth finishing, and why the seeds are a bad idea.
• Cannabis Leaves Clawing: What "The Claw" Actually Means — Clawing is a posture, not a disease — dark green talons usually mean nitrogen toxicity, but four other causes produce the same shape. How to tell them apart.
• Light Burn and Bleaching: Too Close, Too Bright, or Too Hot? — Pale or white upper leaves and bleached bud tips mean the canopy is taking more light than it can use. How to tell light burn from heat and from nutrient burn, and what to change.
• Nutrient Burn: Why Cannabis Leaf Tips Turn Brown and Crispy — Burnt tips mean too much salt at the root, not too little food. How to confirm it, flush correctly, and work out which of four habits caused it.
• Nutrient Lockout: When Feeding More Makes It Worse — Lockout looks exactly like deficiency but has the opposite fix. How to confirm it from runoff pH and EC, flush correctly, and stop it recurring.
• Powdery Mildew on Cannabis: White Dust That Wipes Off — PM sits on the leaf surface rather than inside it, which makes it easy to spot early and hard to eradicate late. What it needs to grow and how to take that away.
• Root Rot in Cannabis: Brown Roots, Sour Smell, Stalled Growth — Healthy roots are white and smell of nothing. Brown, slimy, sour-smelling roots mean the root zone ran out of oxygen. How to confirm it and what actually turns it around.
• Spider Mites on Cannabis: Stippling, Webbing and How to Break the Cycle — Tiny pale dots on leaves and fine webbing in the tops mean mites. Why one treatment never works, what the egg cycle forces you to do, and what to avoid in flower.
• Seedlings Not Growing: Why Week Two Stalls — A seedling that sits still for days is usually being given too much, not too little. The five habits that stall young plants, in the order worth checking.
• Thrips on Cannabis: Silvery Leaf Damage and Black Specks — Thrips scrape leaf surfaces and leave a metallic sheen with tiny dark frass. How to tell them from mites, and why the soil stage is the one most growers miss.
• The First Ten — free WiFi sensor for ten finished grow journals — Log a grow from start to harvest in Cultivar, publish it, record your dry weight. The first ten growers to do all three get a free WiFi temperature and humidity sensor, shipped.
• Yellow Leaves on Cannabis: a 6-Question Decision Tree — Yellow leaves have six common causes and they look almost identical. Answer six questions in order and you will land on the right one — plus what to do about it and how to know it worked.

Who writes this and where the numbers come from: about · methodology.

Track your own grow free — the journal grades your environment against these bands →