When it comes to light, marijuana requires a lot of it. In fact, it is feasible to keep the lights on 24 hours per day to achieve the maximum growth potential.
1. Lighting indoors
Adjustable light tracks are ideal when you have a large grow room and little electricity so that you can move the lights around to every part of your garden. This way, every plant gets intense amounts of high-quality light.
Distance Try to keep a sharp eye on the distance between the lights and the top of the plant canopy; 20 to 30 inches is usually perfect. The accelerated rate at which the plants tend to grow will cause them to inch closer to the lights almost on a daily basis.
So, be sure to place the lights close enough so that they provide adequate light energy, but far enough away that they don’t burn the tips of the leaves.
Temperature control If you want to avoid this, install an air-cooled or water-cooled system that will essentially reduce the heat that the lights produce. Electric light bulbs produce both light and heat whenever they are turned on.
Of course, if you let them go unchecked, they can create incredibly hot temperatures. But, if you want to make use of all the light they have to offer, a cooling system will allow the lights to get closer and work better in the long run.
It should also be noted that certain lights emit different color spectrums.
When we talk about visible light, we’re referring to all the colors that we can see which is often represented by “ROYGBIV” (red, orange, yellow, green, blue, indigo, and violet).
2. Light strength
Marijuana tends to thrive under light that is strong in the red spectrum. This promotes photosynthesis, which is vital for tissue production during vegetative growth. High-pressure sodium (HPS) lamps produce the most light in the red spectrum (and the most light in general) and are often the best choice during virtually every stage of the growing process.
Intensity Depending on the intensity of the lights you use, the plants will need about 25 to 35 watts per square foot. The seeds won’t need light to germinate right away, but it’s common for growers to turn the lights on after sowing the seeds to warm the soil and promote germination.
It’s also a good idea to keep the lights on and ready for when the first sprouts appear out of the soil. Using anything that is high in the green spectrum will produce wilted, unproductive plants in general. This is largely because the plants reflect green light entirely, which is why they are green in color themselves.
3. Control
Perhaps the best thing about growing marijuana indoors is that you have more control over virtually every aspect of the growing process.
While the seeds themselves won’t need light initially, they will certainly need some light when they produce visible sprouts. Light acts as their sustenance during this period of time, and it can affect the plants later in life if they are deprived of the valuable light they require. This assumes, of course, that the soil, nutrient quality, and watering regimen are all adequate as well.
Distance At this delicate stage, the lights should be somewhat close to the marijuana plants. In fact, dropping them down to about four inches away from the soil is ideal if you use fluorescent lights.
Light Cycle The light cycle should also be relatively consistent at around 16 to 18 hours of light per day. This will be the light cycle for a majority of the plant’s life, but it can be hard to maintain a reliable schedule. To remedy this, you can purchase an automatic timer, which only costs about $8 and will let you focus on other things.
Depending on the particular strain, some plants could stand to use a more intensive light regimen. Cannabis really tends to absorb light voraciously because it is a high-energy plant. Some marijuana growers have been known to expose their plants to a light cycle with a full 24 hours of light.
Most growers won’t have to go to those extremes, but you may need to increase the light cycle to over 18 hours at some point if you want to improve growth. Of course, an automatic light timer can make this considerably easier and some lights actually come installed with a timer.
As the marijuana plant ages and starts to grow, the lights should still remain as close to the leaves as possible without damaging them.
The instructions on the lights might tell you to keep them at a certain distance from the plants, but cannabis requires a lot of light energy to thrive. In fact, with lower output bulbs, you can place the lights 2 to 4 inches away from the tops of the leaves. For higher output bulbs, you can place them 4 to 6 inches from the tops of the leaves.
