Question: Dear Ed – Why do some growers stick their plants with thumbtacks? I saw a picture, but can’t find any info.
Ed’s Rosenthal: Dear Scott – When people first started growing domestically, some growers initially thought THC (the active ingredient in marijuana) was produced by stress. They thought up all kinds of ways to stress (TORTURE) the plant. It was thought that putting a thumbtack in the stem would cause some kind of stress as well as supply “needed” metals.
THC is produced to protect the plant from certain stresses including predation but perhaps also as protection against UV light, not tacks.
One indication of this is that high quality marijuana plants produce more THC under high UVB light.
Send your grow questions to Ed Rosenthal at email@example.com