Pillar Guide
Plant Training, Pests and Troubleshooting
Training multiplies what your light can do, and early pest and deficiency detection protects it. These two topics belong together because both are about reading the plant.
Training is free yield
An untrained plant sends most of its energy to one dominant top while lower sites become larf. Topping removes that dominance and low-stress training spreads the branches sideways so light reaches many colas at similar intensity.
Stop all high-stress training by about week two of flower. After that the plant is committing to bud sites and recovery time comes directly out of your harvest.
Catch pests in week one, not week six
Spider mites, thrips and fungus gnats are all trivial to beat early and miserable to beat late. Check the undersides of leaves with a loupe every week and keep yellow sticky cards in the tent as an early warning system.
Prevention is mostly environmental: moving air, no standing water, no soggy topsoil, and clean intake air.
Read symptoms by location
Mobile nutrients — nitrogen, phosphorus, potassium, magnesium — get pulled from old growth first, so those deficiencies start at the bottom of the plant. Immobile nutrients like calcium, sulphur and iron show up on new top growth.
Before changing anything, check pH and runoff EC. Most apparent deficiencies are lockout from pH drift or salt buildup, not an actual shortage in the bottle.
Run the numbers
Gear for this stage
Wireless Temp & Humidity Reader
$34Logs VPD-friendly temp/RH data to your phone with min/max alerts.
Breathable Fabric Pots, 5 Gal (5-Pack)
$29Air-prunes roots for a denser root ball and no circling or root rot.
3-Part Fertilizer Set (Grow / Micro / Bloom)
$64Full veg-to-flower feeding program with a printed weekly schedule.
Every guide in this topic
Plant Training
Low Stress Training (LST): Bend, Don't Break
Plant Training
Topping Cannabis: When and How to Cut the Main Stem
Plant Training
SCROG: Using a Screen to Build a Flat, Even Canopy
Plant Training
Defoliation: How Many Leaves Should You Actually Remove?
Plant Training
Mainlining: Building a Symmetrical Cannabis Manifold
Plant Training
Supercropping: Controlled Stem Damage That Boosts Growth
Plant Training
Lollipopping: Cleaning Up the Lower Third
Plant Training
Sea of Green (SOG): Many Small Plants, Fast Turnaround
Plant Training
When to Stop Training Cannabis Plants
Plant Training
How to Train Autoflowers Without Costing Yourself Yield
Pests & Diseases
Spider Mites on Cannabis: Identification and Control
Pests & Diseases
Fungus Gnats: Why They Appear and How to Get Rid of Them
Pests & Diseases
Powdery Mildew: Stopping White Fuzz Before It Spreads
Pests & Diseases
Thrips: Silvery Scars and Black Specks on Leaves
Pests & Diseases
Root Rot: Brown Slimy Roots and How to Save the Plant
Pests & Diseases
Aphids on Cannabis: Sticky Leaves and Curling Growth
Pests & Diseases
Integrated Pest Management for a Home Grow Tent
Pests & Diseases
Neem Oil on Cannabis: How to Use It and When Not To
Pests & Diseases
Why You Should Quarantine Every New Clone
Pests & Diseases
Yellow Leaves on Cannabis: A Diagnostic Walkthrough
Troubleshooting
Drooping Cannabis Plants: Overwatered or Underwatered?
Troubleshooting
Nutrient Lockout: When Feeding More Makes It Worse
Troubleshooting
Clawing Leaves: The Nitrogen Toxicity Signature
Troubleshooting
Plant Stopped Growing: A Systematic Checklist
Troubleshooting
Purple Stems: Genetics, Cold, or Deficiency?
Troubleshooting
Heat Stress: Tacoing Leaves and What to Do
Troubleshooting
Windburn: When Your Fans Are Too Strong
Troubleshooting
Hermaphrodite Plants: Spotting Nanners Before They Seed Your Crop
Troubleshooting
Why Are My Buds Airy and Loose?
Troubleshooting
How to Read a Cannabis Leaf Like a Diagnostician
Frequently asked questions
- When should I top a cannabis plant?
- Once it has four to five nodes, usually two to four weeks into vegetative growth, and only when it is growing vigorously. Give the plant three to five days to recover before any further training.
- How do I get rid of spider mites?
- Catch them early with weekly leaf-underside checks, isolate the plant, and treat repeatedly on a three to five day cycle to break the egg-hatch sequence. Raise airflow and avoid hot, dry, still conditions, which mites prefer.
- Why are my cannabis leaves turning yellow?
- Yellowing that starts on the lower, older leaves usually means nitrogen is being relocated upward — either a real shortage or lockout from pH drift. Yellowing on new top growth points to calcium, sulphur or iron availability. Check pH and runoff EC before adding anything.