Cannabis Plant Diagnostic Tool
Something wrong with your plant? Select the affected areas and symptoms to get an accurate diagnosis with step-by-step solutions.
Step 1: Where is the problem?
Tap the areas of your plant that look affected. You can select multiple zones.
Cannabis Nutrient Deficiency Quick Reference
| Element | Key Symptoms | Where It Shows | Quick Fix |
|---|---|---|---|
| Nitrogen (N) | Uniform yellowing | Lower/older leaves | Increase N, check pH |
| Phosphorus (P) | Purple stems, dark leaves | Whole plant | Bloom nutrients, warm roots |
| Potassium (K) | Brown crispy edges | Mid-lower leaves | PK supplement, check pH |
| Calcium (Ca) | Brown spots, curled tips | New growth | CalMag supplement |
| Magnesium (Mg) | Interveinal chlorosis | Lower leaves first | Epsom salt or CalMag |
| Iron (Fe) | Interveinal chlorosis | New/upper leaves | Lower pH (most common cause) |
| Sulfur (S) | Uniform yellowing of new growth | Upper leaves | Epsom salt, check nutrients |
| Manganese (Mn) | Chlorosis with brown spots | New leaves | Lower pH, micronutrients |
| Zinc (Zn) | Twisted, distorted growth | New growth | Lower pH, reduce excess P |
Common Issues by Growth Stage
Seedling
- Damping off (overwatered seedlings)
- Nutrient burn from hot soil
- Stretching from insufficient light
- Overwatering (most common mistake)
Vegetative
- Nitrogen deficiency (high demand)
- pH lockout from drift
- Pest establishment (mites, gnats)
- Calcium/magnesium deficiency in coco
Flowering
- Potassium/phosphorus deficiency
- Bud rot in dense, humid environments
- Powdery mildew from poor airflow
- Heat stress causing foxtailing
- Nitrogen toxicity from not switching to bloom nutrients
Prevention Basics
pH management is non-negotiable. The single most common cause of cannabis growing problems is incorrect pH in the root zone. Invest in a quality pH pen and check every feeding. Soil should be 6.0-6.8, coco and hydro should be 5.5-6.2. When pH drifts out of range, nutrients become unavailable even though they are present, creating the appearance of multiple deficiencies at once (lockout).
Water correctly for your medium. Overwatering is the number one killer of cannabis seedlings and a leading cause of root problems at every stage. Water when the top inch or two of soil is dry and the pot feels light. In coco coir, water daily (or more in flower) but always to runoff. In hydro, maintain dissolved oxygen with air pumps and keep temperatures below 68F.
Prevent pests before they start. Quarantine any new plants for at least a week before introducing them to your grow. Use yellow sticky traps as early warning systems. Preventive neem oil sprays during veg are far easier than treating an active infestation during flower when you cannot spray buds. Keep your grow space clean, remove dead plant material, and inspect leaves (especially undersides) regularly.
Monitor your environment. Use a thermometer and hygrometer to track temperature and humidity. Cannabis performs best at 70-82F with 40-60% relative humidity during flower. Large swings between day and night temperature promote diseases like powdery mildew. Good airflow through the canopy prevents moisture buildup that fungi and mold thrive in.
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