Purple or red stems can be caused by several factors, including genetics, phosphorus deficiency, pH imbalance, or cold stress.
If your strain isn’t naturally purple, here’s what to check:
🌡️ Temperature: Keep night temps above 68°F (20°C) — cold nights restrict nutrient movement and cause color changes.
⚗️ pH Balance: Out-of-range pH can cause phosphorus lockout, leading to purple stems even when nutrients are sufficient. Keep pH between 5.8–6.2 (coco/hydro) or 6.0–7.0 (soil).
🌿 Nutrition: Slightly increase Bloom (0-5-3) or Clyde (3-6-5) to ensure adequate phosphorus during the early flowering phase.
Some coloration is harmless and genetic, but if purple stems appear alongside slow growth or pale leaves, it’s a sign of a nutrient uptake issue — usually linked to pH or temperature.