Generally we all worry about the wattage of our lamps, but they can’t all be measured in the same scale, for example, efficiency of COBs in comparison to HPS. PAR on the COBs is way higher than it is on a HPS lamp with the same wattage. I know there are guidelines as to how much light is enough, what the minimum required, in PAR, PPFD, umol-s or even DLI… Anybody here know?
I’ve seen mention of up to 65 mol/d and according to purdue university studies on different plant species, most other light loving plants like sunflowers and tomatoes are recommended for a DLI between 22 and 30mol/day.
So for cannabis, bottom threshold for optimal growth and photosynthesis is a DLI of DLI of 22 would be:
24/0 schedule: 254.6 micromoles/m2/s-1
18/6 schedule: 339.5 micromoles/m2/s-1
12/12 schedule: 509.25 micromoles/m2/s-1
For Cannabis, the Top threshold for optimal growth and photosynthesis is a DLI of 65 moles per day.
***extremely important notice, only go up to these amounts if you are using supplemental CO2, do not go this high if you are not using supplemental CO2 as you will actually slow down photosynthesis and waste energy.
24/0 schedule: 752.31 micromoles/m2/s-1
18/6 schedule: 1003.08 micromoles/m2/s-1
12/12 schedule: 1504.6 micromoles/m2/s-1
The generally accepted guidelines for artificial light PPFD in flowering are this:
in a 12/12
PPFD of at least 510 micromoles/m2/s-1 for the low end of optimal intensity
PPFD of at least 800-1100 micromoles/m2/s-1 for perfect optimal lighting without additional CO2.
PPFD of at least 800-1500 micromoles/m2/s-1 for perfect optimal lighting WITH additional CO2.