Light deprivation is particularly interesting for outdoor cannabis growers seeking new ways to accelerate the flowering process. With this valuable technique, also known as 'light dep', harvests become bigger and more numerous, even in regions with rather humid and cold climates.
How? By manipulating the hours of light outdoor plants receive. It's more or less as if we could turn lights on and off with a switch, making plants grow at will. For example, if we reduce the number of sunlight hours, plants will think autumn is approaching and will thus speed up the flowering process. The good news is that we will be able to 'create' two or more autumns every year.
Force them to (also) flower in July
European grows are believed to receive on average 12.5 hours of sunlight in September. In winter, they get no more than 7-9 hours. This means that most cannabis plants finish their flowering in October or in early November at the latest. Pinning all our hopes on just one shot is rather risky for the low temperatures and heavy rainfalls typically happening in autumn can lead to the appearance of fungal diseases and ruin the work of a whole year.
With the light deprivation technique, we force them to flower during the first half of the summer, when the temperature is more favorable and we get a far lower risk of mold and root rot, resulting in better quality harvests. This induced flowering and early harvest will not affect the budding in autumn, though.
First in, then out
The one thing we need to remember when putting this technique into practice is to cover our plants with a 100% light-proof cover. However simple this may seem, it's important to make sure no mistakes are made for it could be fatal.
To obtain two harvests per season, plants must be arranged in two different groups. Take the first one indoors and grow it with the help of artificial lighting 'till spring kicks off and it can be moved outside for the flowering to be induced. There, it's very important to use a quality black tarp that totally blocks out the sun.
That'd be the moment to start out with the second group. Exactly in the same way, it should be kept indoors until the first group of plants has been harvested and this one can be moved out. In this case, days will start to naturally become shorter, so it won't be necessary to artificially modify the hours of light.
More hours of darkness in the evening or in the morning
As stated before, it's crucial to make sure plants receive the right number of sunlight hours. That's why we should ensure that they consistently get less than 12 hours of light and enjoy, at least, 12 hours of darkness. Plants should be covered up or fully exposed. There's no in-between. Alternatively, if your plants are still rather small, you could consider moving them into a dark room without having to get any tarps. Be careful, though, for they could stress out and the results won't be as expected.
The two annual equinoxes are the only times when the number of hours of light and of darkness are equal. Therefore, it's essential to choose the right moment to provide our plants with those additional hours of darkness. Some prefer the evening; others, the morning. It depends mostly on our personal habits or our availability.
- If we decide to do it in the evening, we must cover up the plants before dusk begins to fall. Don't forget to remove the cover before going to bed so plants can enjoy the warmth of a natural sunrise. This way, we make sure they receive a minimum of 12 hours of darkness, including those during the night cycle. If we know the sun rises by 6 o'clock, then we'll have to cover up our plants by 6 p.m. and gradually modify our timing according to the natural movement of light. Summer, from June 21 to September 21, is a long run where days start to become increasingly shorter, all depending on the latitude you're in, of course. So your schedule may have to progressively adapt to this change.
- Other cannabis growers simply prefer adding those hours to their mornings. In this case, we've got two options: covering our plants at night and during sunrise (being extremely careful with ventilation to prevent a heat and moisture build-up that could eventually lead to the development of fungi) or wake up early in the morning before the sun rises to cover them up and avoid the first hours of sunlight. In any case, it's important to get the times right and be consistent with the dark/light schedule. If it gets dark at 8 p.m., then we must uncover our plants 12 hours later, at 8 a.m.
Some additional tips
If you follow our advice, you're quite likely to get the desired results. However, we've got some other additional tips that could be of great use. Do you want to hear them?
- Doing things manually is always great and many regard it as more traditional and even more valuable. Even if that's true, automating some processes using timers or electric curtain rails, particularly when growing in a greenhouse, could make a tedious task far simpler and all possible human mistakes would be avoided.
- The most important aspect when forcing our plants to flower is to ensure they consistently receive 12 hours of complete darkness every day. When in doubt, darkness is always better than light. Make sure there're no street lights, traffic lights or neighbors nearby that could cause light pollution.
- The climatic conditions in the area cannot be overlooked. If our plants are located in a windy spot, they are better off in a greenhouse. But remember: the curtains and tarps should be installed indoors so the strong gusts of wind don't move them and light gets to reach our plants when it shouldn't.
- Light dep outdoors has not only a very low environmental impact but the main advantage of outdoor growing: plants feed on sunlight, which definitely provides an extra kick. On top of that, since plants don't have enough time to turn into chunky beasts, growers can put them closer, leading to improved efficiency of every square meter.
Light deprivation is relatively easy. Far easier than it actually seems. All we need to do is carefully control every step of this process. By the time outdoor growers are waiting for their buds to fully develop, we will have already harvested our plants and it'll be time to enjoy them. Follow our tips and get generous quality yields. Enjoy it!