Hey, so just by looking at the photos, I see signs of significant plant stress, characterized by widespread yellowing (chlorosis), necrotic brown spotting on the leaves, and reddish-purple stems.
These symptoms often point to a combination of environmental and nutritional issues rather than a single cause. Below is a breakdown of the most likely culprits based on the visual evidence:
1. pH Imbalance (Most Likely Primary Cause)
When the pH of your growing medium is outside the optimal range (typically 6.0–7.0 for soil), the plant experiences “nutrient lockout.” Even if you are providing nutrients, the roots cannot absorb them, which causes symptoms that mimic multiple deficiencies simultaneously.
Why it fits: The combination of yellowing and spotting across different areas suggests the plant is struggling to uptake several mobile and immobile nutrients at once.
2. Nutrient Deficiencies
Nitrogen Deficiency: The general yellowing, especially if it started from the bottom and is moving upward, is a classic sign of nitrogen deficiency, which is common during vegetative growth.
Calcium/Magnesium (CalMag) Deficiency: The brown, “rusty” spots and the reddish stems are frequent indicators of a calcium or magnesium deficiency. Calcium is vital for cell wall structure, and its absence often leads to these necrotic spots and weak stems.
Potassium Deficiency: If the edges and tips of the leaves are turning brown and crispy, or if the leaves are curling/twisting, it may indicate a lack of potassium.
3. Watering and Root Health
Overwatering or Drainage Issues: The drooping appearance and the yellowing can be caused by root suffocation from overwatering or poor drainage. If the roots cannot get enough oxygen, they become unable to transport nutrients effectively.
4. Pests or Fungal Infections
While nutrient issues are more likely, Leaf Septoria or fungal “rust” can also cause rust-colored spots. Check the underside of the leaves for signs of pests (like spider mites or aphids) or fuzzy mold growth, especially if the growing environment is humid or lacks proper airflow.
Recommended Steps to Address the Issues
Check and Adjust pH: This is the most critical first step. Ensure your water and runoff pH are in the correct range (5.8–6.2 for hydro/coco, 6.0–7.0 for soil).
Evaluate Watering: Ensure the pots have proper drainage and allow the soil to dry slightly between waterings. Do not let the plant sit in stagnant water.
Improve Airflow: Ensure there is adequate ventilation and fans to prevent stagnant air, which encourages fungal issues.
Check Environmental Factors: Ensure the light source isn’t too close, which can cause bleaching or heat stress, and monitor temperature and humidity.
Consult a Feeding Schedule: If the pH is correct, consider if the plants are being underfed or if there is a nutrient salt buildup in the soil that needs flushing.
Hope this helps a little. Good luck 
