Many producers may attempt to add more light than required to an indoor grow environment in order to feed their plants with as many photons as possible, but there is a limit to the density of photons that cannabis plants can consume. Larger cannabis plants may tolerate greater PPFD concentrations, up to 1500 mol (PPFD), assuming sufficient supplementary CO2 is given consistently to the grow room and other environmental parameters like as temperature and relative humidity are also appropriate. Their light intake is partly limited by the quantity of CO2 in the air.

If PPFD levels surpass 2000 mol (PPFD) inside, the quality and quantity of crops may be compromised in severe circumstances. Excessive PPFD levels might ultimately cause harm to plant tissue. As a consequence of intense illumination, plants will attempt to defend themselves via photoprotective reactions. Photoinhibition slows photosynthesis in response to light stress. When photoinhibition is no longer effective in protecting a plant, chlorosis will ultimately set in.

Cannabis Home growers and commercial growers have different PPFD requirements.

Cannabis requires a PPFD of 100-300 mol/m2/s during seedling, 400-600 mol/m2/s during vegetation, and 600-800 mol/m2/s during flowering for ordinary home growers. Commercial growers require 600-800umol/m2/s during vegetative growth and 800-1000umol/m2/s or greater during flowering.These are the fundamental photons required for the growth of healthy, active marijuana.

While many farmers believe that the greater the PPFD, the higher the yields, this is not always the case. However, increased PPFD does not necessarily equate to increased potency. Indeed, each plant has a "saturation point" beyond which the advantages of PPFD begin to wane. At particular stages of development, excessive light may raise the danger of light burn, nutrient burn, or water deprivation