Cannabis
A plant genus whose members produce cannabinoids, including THC and CBD.
Read more about Cannabis
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
Yellowing lower leaves: what it is, and when it’s nothing
Before anything else: if you're six or more weeks into flower and it's only the bottom leaves, this is probably normal.
Leaf Doctor
Natural senescence: when yellowing leaves are supposed to happen
Late in flower, your plant starts dismantling its own fan leaves on purpose.
Leaf Doctor
pH lockout: why feeding more makes it worse
A plant can be surrounded by a nutrient and unable to use it.
Policy
Sample: State regulators propose tighter lab testing rules
Labs would have to report results the same way, and products that fail could not be retested elsewhere.