There is no better light source for plants than the sun. Therefore, the task of the indoor grower is to reproduce the spectrum and intensity of sunlight as accurately as possible at home. It is still far from the solution of this problem.
Picture. This indoor grow tent uses two MH Marijuana plant grow light
Simultaneously, using artificial lighting for indoor marijuana cultivation presents several benefits. Employing grow lights for marijuana plants allows us to have full control over the greenhouse conditions, significantly enhancing the quality of the final product.
However, these plant grow lights (commonly known as grow lamps) can often perplex novices. With such a vast array of options, how can one determine which lamps, ballasts, and reflectors are the best? As usual, science provides the most precise answers.
Scientific research informs us precisely about the needs of plants, alleviating our uncertainties. For instance, we understand that plants require a full spectrum of light for optimal growth, as they have evolved under natural sunlight over millions of years. Additionally, we know that plants need a specific amount of light energy for photosynthesis.
Only with this can they grow correctly, become robust, and yield a bountiful harvest of buds. So, what insights does agricultural science offer us?
DNAT / MH
Regardless of whether you grow in a closet, grow tent, basement, or attic, the type of lamp you choose significantly affects the quantity and quality of your harvest.
High-power gas discharge lamps, such as DNAT and MH, remain the top choice for home growers, catering to both beginners and seasoned professionals. The key question is: what should be the lamp's wattage? This depends on the size of your grow space, the number of plants you intend to cultivate, and your budget.
MH lamps are traditionally used during the vegetative stage, which typically lasts between two to four weeks, although this can extend if you have the time, space, and desire to grow larger plants.
MH lamps emit a whiter light with a blue spectrum, which reduces the spacing between nodes, resulting in shorter and bushier plants. This characteristic is usually ideal for home growers.
For the flowering stage, HPS lamps are preferred. These lamps emit light with a pronounced orange hue, closer to the spectrum of autumn sunlight.
The increased energy in the red part of the spectrum promotes branch elongation once flowering begins. Notably, many experienced growers use both HPS and MH lamps simultaneously to achieve a fuller light spectrum and provide more energy for flowering marijuana. However, this approach depends on whether you have enough space for two lamps and whether you can accommodate the additional energy consumption.
Picture. On the left - clones under fluorescent lamps, and on the right - mother plants under MH.
Modern models also include lamps with dual bases, designed for use with electronic and digital ballasts. These lamps can endure the higher frequencies of such ballasts without suffering the shortened lifespan typical of previous generations.
Examples of such lamps include Gavita, which are often used in place of HPS lamps due to their more comprehensive spectrum that includes more blue light. Another excellent type of grow light is the CDL (Ceramic Burner Lamp), which is well-suited for marijuana cultivation.
Although these bulbs are usually less powerful, they still provide sufficient light energy for your garden. Both CDL and Gavita dual-base lamps generate considerable heat, so additional cooling is necessary for those using smaller grow spaces.
Energy-saving lamps
Energy Saving Lamps (ECLs) are a great option for hobbyist growers who don't need large yields. ESLs heat very little, give a good spectrum and consume little energy. True, these lamps give little light energy to plants. This is why energy saving lamps are not recommended for the flowering stage and are generally used for sprouts and clones - they get enough light, but it is so soft that it cannot damage them. ESL are also perfect for mother plants or for the vegetative stage in mini-boxes.
LED plant grow light
As we know, two factors influence the development of plants under phytolamps: spectrum and intensity of radiation. Both yield and quality depend on them (in the case of marijuana, psychoactivity). Full spectrum light is as white as the sun. PAR (photosynthetically active radiation) is used to measure light energy. These two factors should be taken into account when evaluating the potential of LED lamps.
LED is a new (just five years) direction in the production of lighting systems for plants. They have their advantages and disadvantages. The advantage is that they consume less energy and heat less than, for example, DNAT. This is a great property for hobby growers and growhouses. However, the disadvantages of LED are also serious. This is a limited spectrum and light energy, which means that the yield of marijuana under LED lamps is low.
Picture. LED plant grow light with side UV tube.
Recent advances in LED technology have overcome some of their disadvantages. New generation LEDs use 5-watt diodes, giving more energy, and more LEDs of different colors are built into the luminaires, which gives a more complete spectrum. However, this progress has been made at the expense of higher energy consumption. Accordingly, such lamps get hotter, and they are much more expensive.