The level of photosynthetic flux emitted by the artificial lighting system directly influences plant growth. The greater the amount of energy captured and accumulated, the better for all the photobiological processes associated with this growth. However, there is a limit to the rate of energy that can be absorbed, beyond which plants enter saturation, no longer absorbing more energy and, worse still, spending additional resources on this process. In extreme situations, plants can enter a process of degradation due to oxidation of the chlorophylls. Clearly identifying the applicable saturation levels is therefore fundamental to finding the best compromise between growth and profitability.

This saturation limit varies from plant to plant. In the case of medicinal cannabis plants, the levels range from 200 umol/m2/s in the propagation phase to 800 umol/m2/s in the flowering phase.

The amount of energy accumulated by plants over a 24-hour period dictates their growth conditions (circadian rhythm). The greater the amount of energy captured and stored, the greater the amount of energy available for the different associated photobiological processes, and therefore the greater and better their growth. However, as with the density of the energy rate, here too there are limits to the amount of energy that plants can store and from which they will activate rejection mechanisms, consuming precious resources, in addition to the energy waste itself.

In the case of medicinal cannabis plants, the level of DLI varies between 13 mol/m2/d and 32 mol/m2/d, depending on whether the growth stage is propagation or flowering.

The spectral quality of a light source is another fundamental factor in the plant growth process. It is an indicator of how the emitted energy is distributed in the absorption zone (PAR), i.e. a measure of its spectral richness. The more complete this spectrum is, the more complete the range of components available for plants to carry out the different tasks necessary for their growth.

Even so, since not all plants have the same energy needs, depending not only on the type of plant but also on the type of use envisaged, the higher the selectivity of the lighting solution, matching the emitted spectrum with the regions of maximum absorption, the greater its efficiency, reducing energy costs and environmental impact. The combination of the two factors quantity and quality dictates the effective overall value of the lighting solution provided.

In the case of medical cannabis plants, the weight of each of the photobiological processes involved in their growth depends on the stage these plants are at. It also depends on the physiological and morphological requirements to be met. Despite everything, the photosynthetic process always plays a central role as it is the main mechanism for capturing energy. In this sense, lighting systems should always be designed primarily to maximize the energy captured in the chlorine absorption regions.

In the case of medicinal cannabis plants, the photoperiod depends on the different stages of growth and is quite strict in each of these stages. As these plants grow naturally at low latitudes, they are prepared to work with a high level of exposure to the sun, so photoperiods are always high.

The number of hours of exposure to artificial light must be respected so that the plants can carry out the different tasks necessary for their growth as efficiently as possible. If the rest periods are not respected, the plants will struggle and this will not only lead to their degradation, but also to a lack of control over the different photobiological processes, which will greatly affect the results obtained.

The photoperiod normally fluctuates between 12 and 18 hours, depending on whether the associated growth phase is flowering or vegetative growth.

Controlling the photobiological rhythm of plants (and all living things in general) is fundamental to regulating their internal functioning. This rhythm is imposed by the length of the solar day, more specifically by the sequence of day and night. It is essential to control this rhythm, respecting the planned photoperiod, otherwise the plants will struggle, degrade and ultimately perish.

In the case of medicinal cannabis plants, this is especially critical given their commercial value and the level of investment usually involved.

The uniformity of energy levels and their spectral components is essential if medicinal cannabis plants are to grow as uniformly as possible at all stages of growth. The higher its value, the better the results obtained, so the artificial lighting system must guarantee the right conditions for this to be a reality.