How much light can cannabis plants get?
Light is essential for cannabis plants to reach their maximum potential. When you grow marijuana outdoors, sunlight is your light source, and marijuana plants can absorb a lot of sunlight. If marijuana is grown indoors, the plant grow lamp is the main light source of marijuana.
“The more light, the better” is often heard, but there is a limit to the photon density (PPFD) that cannabis plants can use. If plants are exposed to higher densities of photons than they use for photosynthesis, it will not increase production. In fact, when PPFD is too high, the yield and quality of harvested cannabis will be reduced.
The rate and efficiency of photosynthesis may be limited by several factors, including carbon dioxide, photon density, temperature, oxygen, water, minerals, age, leaf anatomy, etc. Photon density is the limiting factor in many planting tents. However, with the increase of photon density, other factors such as carbon dioxide will become limiting factors. When photosynthesis is limited by any factor other than light, leaves reach the light saturation point.
The photon density of plants will exceed the specified point of photosynthesis (PPFD). Therefore, when the leaves reach the saturation point, plants will try to protect themselves through photoprotective response. These include chlorophyll or leaf movement, anatomical changes, non photochemical quenching and heat dissipation. All this light protection of plants wastes energy and reduces production.
If a plant cannot adequately protect itself from excessive light energy by using a photoprotective response, it will begin photoinhibition. Photoinhibition reduces the rate of photosynthesis and reduces growth and harvest potential. However, if plants can cope with excessive light, the symptoms of light stress will not become obvious. Only when photoinhibition can no longer effectively protect plants will there be symptoms such as Verticillium wilt.
Lack of light can produce larvae
When the light in the space is insufficient, it may lead to the decline of marijuana quality and more work pruning. If the plant receives insufficient light and has a large number of germination sites, it will produce larvae.
Too much light is harmful or wasteful
If there is too much light, you can avoid damage by raising or dimming the light. Increasing light will waste energy and reduce efficiency. In either case, if your light matches the space, you will save money and improve efficiency.
Many marijuana experts have published extensive studies on marijuana photosynthesis and provided some reference data. It shows that the cannabis plant is the same as many other terrestrial plants. When the photon density of hemp leaves is 500 µ mol of CO2 (PPFD). The limiting factor is carbon dioxide. This is shown in the data that the CO2 concentration in the leaves decreases when the photon density is higher than 500 µ mol / m2. At this time, increasing photon density will produce a diminishing return, but it will lead to more photosynthetic activity. However, there is a limitation. When the photon density reaches 1000 µ mol / m2 (PPFD), the cannabis plant begins photoinhibition. An additional photon density of more than 1000 µ mol / m2 (PPFD) will reduce the rate of photosynthesis and may damage plant tissue.
These limits mainly depend on the concentration of CO2. The ambient CO2 level is about 370 µ mol. When carbon dioxide levels are high, cannabis plants can process more photon energy before being limited. According to data provided by cannabis experts. It shows that when the CO2 concentration is 750 µ mol, cannabis plants can perform well at the photon density of 1500 µ mol/m2 (PPFD) without causing photoinhibition. This allows for greater gains from the same amount of space. However, successfully increasing the concentration of carbon dioxide in the growth space requires a sealed space. The cost of establishing and operating a sealed planting space is considerable. Most home growers can get better services by using ventilated planting space and accepting the restrictions imposed by environmental carbon dioxide levels.