Light deprivation is an extremely popular outdoor cannabis cultivation technique. It is easy to implement, allows for more than one harvest per outdoor growing season, and can result in much larger yields of higher-quality buds than when the plants are left to their own devices.
Light deprivation (or ‘depping’, as it is more commonly referred to) works by controlling the number of hours of natural sunlight the crop is exposed to in a 24-hour period, to induce the crop to switch from vegetative growth to flowering earlier than it normally would.
Cannabis cultivation, especially at the medium to large scale, is anything but straightforward. To the uninitiated, the idea of growing weed might seem like a walk in the park, but it’s actually way more complicated than many people realize. Cultivation techniques seem to be getting more convoluted by the day, but are they necessary?
Well, that really depends on what you’re trying to accomplish. If you want large yields and multiple harvests in a single season, then yes, some growing techniques are a necessity. Not to fear though, as not every single technique is overly elaborate…
Light deprivation is a simple and straightforward technique used by outdoor cannabis growers to control the amount of light that their crop is exposed to each day.
Well, it all comes down to how the lifecycle of (photoperiodic) cannabis plants work. Weed plants go through two distinct growth stages: vegetative and flowering. The switch between the two stages, for photoperiodic cultivars, is triggered by light; For plants to grow big and strong, they need a solid vegetative period. This kicks in as soon they grow past the seedling stage and is when the plant focuses its energy on growth, root production, and branch development. For plants to stay in the veg stage of growth, they need to be exposed to around 18 hours of light per day.
When the crop is exposed to 12 hours of light or less per day, it will switch the growth pattern over to flower production. In the first two weeks after the light schedule has changed, most strains continue to put on size (known as the final stretch), but once this is over all the plant’s energy is focused on producing buds and trichomes.
This is where light deprivation comes into play. By controlling the amount of daylight the crop is exposed to, growers can essentially trick the plants into thinking autumn has come early, forcing the crop to switch over from veg to flower much earlier than they naturally would have. This comes with a range of advantages, including –
Thanks to the introduction of LED panels, indoor lighting rigs have come along in leaps and bounds in the past few years. But, as good as they now are, they still cannot 100% match natural sunlight when it comes to the range and potency of both terpene and cannabinoid production.
This is why outdoor cultivation of cannabis remains so popular, and it’s also why light deprivation has become such a big thing in the past 20 years or so.
When grown outdoors, cultivators start their crop sometime in early spring, depending on the environmental conditions. This gives the plants a few weeks to emerge from their woody shells, break ground, and get through the seedling stage. Once they are in full vegetative growth, summer is usually just around the corner, and with it comes the long daylight hours. They then spend the whole summer growing and getting ready for the flowering period, and as summer wanes and the days start to shorten to around 12 hours of sunlight, flower production begins.
For cultivators looking to ensure optimal growth, the option to control the amount of light their crop gets is invaluable. Light deprivation tents, greenhouses, and shade cloths can all be used to force crops into flowering earlier than they typically would through creating unnatural dark periods, and they also come with the added bonus of protecting your crop from pests and other nasties, as well as inclement weather.
Ok, so how do growers actually go about setting up a light dipping outdoor grow area?
Well, first up that really depends on the size of your grow op. Light dipping just a handful of plants is pretty straightforward, but a whole commercial crop? Well, that is definitely a little trickier and takes a fair bit of planning.
No matter if you are trying to cover a couple of personal plants or a huge crop, using a shade cloth option that is capable of cutting out 100% of the light when it is engaged is critical. If you allow even the smallest sliver of light to leak through during the dark periods, it can result in a few major issues. From lower-than-expected yields to the plants becoming hermaphrodites and pollinating themselves, light leaks can really ruin a crop and should be avoided at all costs.
If you just want to light dep a single plant (or a few) then you can easily make light dep bags that can be used to cover the plants during their dark periods. These can be made from a number of materials, such as black plastic bin bags or a tarp. But in all honesty, it’s almost always better to build yourself some sort of structure for light deprivation. That way, you can ensure better coverage and a higher level of security from light leaks.
The most common structures used for light depping large-scale outdoor grows are greenhouses or hoop houses.
Greenhouses are a great option for people growing in an area where the climatic conditions are cooler and dryer than the optimum conditions for cannabis growth.
What temperature and humidity ranges are best for cannabis cultivation?
Well, that really depends on the stage of growth. Seedlings like a very humid environment, with around 70 – 80% humidity and a temperature sitting around the 85F mark. Veg growth is best at temperatures between 72 to 82F with humidity dropping to around 55%, and for flowering it is recommended to drop the temps to 72 to 78F, with the humidity also dropping to around 45%.
Not only do greenhouses allow you to fine-tune the climatic conditions, but they also keep your crop safe from inclement weather and pests, and they make light depping much easier. All you need to do is cover the outside of the greenhouse with a blackout sheet when it comes time for dark periods, and voilà! The ease is dependent on the size of the greenhouse, obviously, but for most home growers this shouldn’t be a huge issue.
Hoop houses are perfect for growers looking to set up a light-deprivation tent in an area where the climate is already more than warm enough. Unlike greenhouses, they are not covered during the hours that you are allowing the sun to reach the plants, providing maximum light exposure without any inherent rise in both the temp and humidity. They can also be covered in a netting of some sort which will let the sunshine through while also helping to combat the
chances of any pest infestation occurring or birds eating your buds.
Let’s take a bit more of an in-depth look at both options
Hoop houses are pretty self-explanatory, but for the sake of clarity, they are basically large, arched tent-like structures that provide plenty of room for your plants to grow.
Most often constructed from PVC piping that has been covered with blackout sheeting for the light dep period, hoop houses are great for light depping for a few key reasons…
PVC piping is a pretty invaluable material for outdoor cannabis cultivators. The ridiculous number of uses that can and will be put to during your life as a grower is nothing short of incredible, and the best part? It’s so damn cheap.
It’s also very easy to work with, requiring little effort to cut, bend, and shape into whatever form you need. This makes them a great material for more complex structures like greenhouses and shade houses, which involve a more complicated setup than a simple hoop house.
The size of your plants will determine the size of your hoop house. A bigger is better approach is the way to go with any structure built for housing weed plants, as it allows you to provide the best possible environment for your crop. The last thing you want is to overcrowd the area, and promote fungal or mold growth when the flowering period gets into full swing.
You may want to consider some other plant training techniques to keep the overall size of your plants under control. ScrOGging is a great idea, as it allows you to keep the height and width of your plants under control while still maximizing yields. You can also look into lollipopping – a technique that involves removing all the lower-branching leaves and buds to ensure that your plants are able to push out the juiciest main colas possible.
Greenhouses are used in a huge array of horticultural settings and for a variety of reasons.
When it comes to cannabis cultivation, the ideal temperature and humidity range is pretty specific, and changes as the plants move through their vegetative and flowering stages.
Greenhouses are great for providing the perfect environment for cannabis growth, as with just a little additional investment, you can regulate the temperature and humidity within your greenhouse to suit whatever stage of growth your crop is in.
Like hoop houses, greenhouses are also great for light depping. Covering the outside of your greenhouse with a blackout sheet is super easy (size dependent) but be careful to keep a close eye on the climatic conditions inside when the cover goes over. The extra layer of insulation can make the temperature and humidity rise quickly (especially if the sun is still up), so you’ll need to moderate the airflow within your greenhouse a little more carefully. You may need to invest in an extraction fan or two in order to ensure that the air is moving adequately. Remember, keeping the canopy well-oxygenated is key when it comes to producing the type of yields dreams are made of.
A simple greenhouse is easy to build, but keep in mind that cannabis is a hands-on crop. You will be wanting to inspect and play around with the plants very regularly, so make sure your structure is easy to access without compromising its effectiveness.
The investment for setting up a greenhouse is potentially higher than the cost of a hoop house (although a hoop house can be quickly turned into a greenhouse by simply covering it with an opaque plastic sheet).
The upside of going out and actually investing in a decent greenhouse is that it provides an all-in-one solution for your outdoor cannabis cultivation needs if you are wanting to boost the temperature and humidity. A decent greenhouse provides protection, insulation, and a great environment for your plants to thrive in. And it makes light depping an absolute breeze.
Light depping is great for more than just improving yields – it allows you to manipulate the growth cycles of your plants, meaning you can effectively control when your harvest will be ready.
This is especially useful for outdoor grows, as poor weather, pests, and fungal diseases are all potential crop killers. If you can control when your harvest will be ready, you can go a long way in avoiding these issues and ensuring the biggest and best buds possible.
It is also especially useful for those growing in less-than-ideal climates, as light depping can help replicate the type of environment that would be found in more favorable climates. Take the pacific northwest as an example (one of the most fertile cannabis breeding grounds in the world, but also an area with less than ideal weather at times). Light depping is a very common practice in this region, and it allows growers to get the most out of their crops during those cooler months, and ensure the crops finish before the cold weather really kicks in.
Light depping also gives you the opportunity to get multiple harvests in a single season, something that can be incredibly beneficial for both commercial and personal growers. It also allows for a perpetual harvest routine to be implemented, which can be super beneficial when it comes to crop management. It also allows for staggered harvests, which takes a bunch of the pressure off come harvest time. Instead of having to cut, dry, trim, and cure the entire crop in one go, you can stagger your harvests and spread out your work over a much longer period of time.
When comparing the results of light depping with those of a regular outdoor grow, it’s easy to see why more and more growers are taking the plunge and investing in a light depping system.
Light-depped crops are generally much more robust, with bigger buds that contain higher concentrations of both terpenes and cannabinoids. The resulting bud is tastier, more aromatic, and denser – and comes with a thicker coating of those resinous trichomes we all know and love.
Light-depped crops also tend to have increased yields, and while the actual increase varies from strain to strain, and grower to grower, it can range anywhere from 20% to 50%. That’s a huge increase when you consider the relatively small investment required for most home growers when making the switch to light depping. Sure, that initial investment increases quite dramatically when implementing light depping in a commercial setting, but the returns make the start-up costs worth the while.
Ultimately, light depping is a great way to increase your yields and control the growth cycles of your plants in an outdoor setting. From controlling temperature and humidity to manipulating the light cycles of your plants with relative ease, it’s easy to see why so many growers are making the switch!
In terms of lighting schedule – to force photoperiodic cannabis strains to stay in the vegetative stage of growth, they must be supplied with 18 hours or more of light per day. Once you are ready for the crop to begin flowering, you will want to make sure that it receives 12 hours of light per day. This will help ensure that the plants enter the flowering stage of growth.
Look, there is nothing stopping you from running your autos under a depping schedule, but it is important to keep in mind that they do not react the same way photoperiodic strains do. Autos will switch to the flowering growth stage after 3 to 4 weeks, no matter what the light cycle is. So, while depping may help boost yields, it won’t really have any effect on when your harvest will be ready. In fact, many growers like to add additional lighting for auto strains, as they believe this helps them reach their maximum potential.
Typically, yes. The initial investment for setting up a light depping system is typically higher than the cost of a regular outdoor grow. That doesn’t mean you have to go out and spend a bunch of cash on a heap of fancy, overpriced equipment (like some websites will have you believe and even try to sell to you). All that’s needed to start a small-scale depping operation is some basic equipment and a decent structure to house it all. Make sure you don’t go too cheap, though. Light leaks are the bane of a grower’s existence, and cheap DIY projects are top of the suspect list for this.
It’s important to remember that the cost of setting up a depping system is often recouped in the form of bigger yields and higher-quality buds, and this can happen in your very first light depped crop. So, when you look at it this way, light depping is really a long-term investment that will pay dividends in the years to come.
While a waterproof cover will help to protect your plants from the elements, it’s not absolutely necessary. That being said, if you are growing in an area where you expect rain during the flowering period, it’s best to try to protect the buds as best you can. Bud rot is no joke, and can ruin a crop in just a few short days, so it’s best to take precautions whenever possible.
So, there we have it. All the reasons why we suggest that all outdoor growers heavily consider light depping. From increased yields to better quality buds, there are many advantages when it comes to switching from regular outdoor growing to a light depping regimen.
But don’t take our word for it, give it a try yourself! Home-growing weed is all about having fun, right? Experimentation is a big part of that, so don’t be afraid to try something new and see what happens.
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Sam N. is a content writer with a passion for everything cannabis. After working multiple seasons on weed farms absorbing the ins and outs of cannabis cultivation and culture, he decided to transition into a role that would allow him to work from anywhere, anytime. Sam now writes for multiple weed publications. He has extensive experience with a wide range of canna-agriculture styles, from smaller artisanal farms to large-scale commercial operations, and is here to share his knowledge to give you all the best chance of cultivation success. About this Author