Nutrient toxicity
Harm caused by too much of a nutrient, often showing up as burnt tips or dark, stressed leaves.
Also called toxicity
Read more about Nutrient toxicity
Grow guide
Cannabis pH: what the research actually says
The short answer: aim for a substrate pH of 6.5.
Leaf Doctor
Purple stems and petioles: the phosphorus myth
Purple stems are not a reliable sign of phosphorus deficiency.
Leaf Doctor
pH lockout: why feeding more makes it worse
A plant can be surrounded by a nutrient and unable to use it.