Teaching Healthy Cultivation · Diagnostic Index
Start with the symptom. End with evidence.
A visual symptom is the beginning of an investigation, not the name of the problem. Use this index to describe what you see, compare look-alike causes, choose the next useful measurement, and verify whether an intervention actually changed the plant response.
Diagnostic ladder
Use the same four steps every time.
The order matters. Starting with a product or a deficiency name creates confirmation bias before the plant has been described.
Describe
Name the affected organ, tissue, color, shape, distribution, and progression without assigning a cause.
Context
Add developmental stage, environment, light, root-zone conditions, irrigation, recent changes, and plant identity.
Compare
List more than one plausible cause. Look for evidence that separates them instead of collecting only confirming clues.
Verify
Choose the smallest justified change, record it, then remeasure or reobserve to see whether the interpretation was useful.
Symptom-first index
Compare causes before choosing one.
These are differential categories, not diagnoses. Multiple stresses can occur at the same time, and confirmation may require repeated measurements, microscopy, testing, or professional laboratory work.
Yellowing / chlorosis
- Old or new leaves first?
- Uniform yellowing or between veins?
- Whole plant or one zone?
- How quickly is it progressing?
- Normal senescence or developmental change
- Root-zone water or oxygen stress
- Nutrient availability / uptake limitation
- Salinity or pH-related availability issue
- Light or environmental stress
- Pest or disease damage
- Plant stage and symptom distribution
- Root-zone moisture and root condition
- Source/feed/sample pH and EC with method identified
- Environment and recent irrigation/feed history
Spots / necrosis / burnt tissue
- Margins, tips, interveinal tissue, or random lesions?
- Dry/crispy or water-soaked?
- Circular, angular, or irregular?
- Associated with pests, droplets, or contact points?
- Salinity / excessive concentration
- Water stress or root impairment
- Light or heat injury
- Nutrient imbalance or localized deficiency
- Mechanical / spray / contact injury
- Infectious disease or pest feeding
- Pattern across multiple leaves
- Canopy light and temperature
- Root-zone data and irrigation history
- Close pest inspection and progression photos
Curling / clawing / distorted growth
- Upward taco, downward claw, twist, or malformed new growth?
- Only tops or throughout canopy?
- New leaves affected before old leaves?
- Any insects on growing tips or leaf undersides?
- Light / heat / low-humidity stress
- Excess nitrogen or salinity context
- Root-zone water imbalance
- Pest feeding on young tissue
- Chemical / spray injury
- Developmental or genetic variation
- PPFD/light position and canopy temperature
- RH/VPD context and airflow
- EC and irrigation pattern
- Magnified inspection of new growth
Wilt / droop / loss of turgor
- Dry medium, saturated medium, or uncertain?
- Whole plant or one branch?
- Recovers after dark or irrigation?
- Roots discolored, damaged, or restricted?
- Insufficient water availability
- Excess water / poor root-zone aeration
- Root damage or disease
- High evaporative demand
- Stem / vascular injury
- Transplant or acute environmental stress
- Root-zone moisture before irrigation
- Container weight or repeatable moisture method
- Air/leaf temperature and humidity
- Root condition and irrigation timing
Slow growth / stunting
- Always small or growth rate recently changed?
- Roots expanding normally?
- Internodes unusually short or long?
- Is new growth healthy but simply slow?
- Insufficient light or carbon gain
- Root restriction / poor aeration
- Water or nutrient limitation
- Excess salinity
- Temperature stress
- Pest/disease pressure
- Genetic or developmental differences
- Growth trend across several days
- Rooting volume and root condition
- PPFD/DLI and photoperiod
- Environment, irrigation, pH/EC, and plant identity
Root discoloration / odor / poor roots
- Cream/white, tan, brown, black, slimy, dry, or damaged?
- Localized or widespread?
- Odor present?
- Media staying saturated or drying excessively?
- Normal staining from media or inputs
- Mechanical injury
- Low oxygen / prolonged saturation
- High salinity or chemical injury
- Temperature stress
- Root pathogen or secondary decay
- Root-zone moisture and drainage
- Temperature and oxygenation context
- EC/sample method
- Microscopy/testing or professional diagnosis when disease confirmation matters
Flower / late-stage problems
- Localized flower damage or whole-plant decline?
- Wetness or condensation inside dense tissue?
- Visible insects, webbing, spores, or decay?
- Normal maturation signals present elsewhere?
- Normal senescence / maturation
- Moisture-driven disease risk
- Pest feeding
- Root-zone or environmental stress
- Mechanical damage
- Pollination / reproductive development
- Canopy and flower-zone humidity/temperature
- Condensation and rain/wetness history
- Magnified flower inspection
- Representative maturity observations and batch records
Visible pests / feeding evidence
- Actual organism seen or only damage?
- Life stage and location?
- Repeated counts increasing or stable?
- Beneficial organisms present?
- Chewing vs piercing/sucking damage
- Mites vs insects
- Pest damage vs disease lesions
- Pest damage vs environmental or spray injury
- Primary pest vs secondary organism
- Repeated scouting counts
- Sticky-card or sample location
- Magnified identification evidence
- Distribution map and follow-up after intervention
Minimum evidence rule
Do not diagnose a plant from one close-up photo.
Capture the whole plant, affected tissue, plant stage, symptom distribution, recent changes, environmental measurements, root-zone observations, irrigation history, and pest inspection. A more complete evidence set usually narrows the problem faster than adding another product.
Go deeper
Open the system that matches the evidence.
Use the subject pages for mechanisms and the Encyclopedia when you need deeper plant-science context.
Water & root zone
Irrigation, pH, EC, salinity, oxygen, root condition, and sampling method.
Nutrition & media
Nutrient roles, availability, media behavior, interactions, and look-alike symptoms.
Environment & light
Temperature, RH, VPD, airflow, leaf temperature, PPFD, DLI, and transitions.
Plant health & IPM
Pests, disease, sanitation, scouting, damage patterns, thresholds, and follow-up.