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Use Light Deprivation to Grow Greenhouse Buds

October 26, 2016


Outdoor cannabis plants have a completely natural day-and-night photoperiod, while indoor plants have lamps that are turned on and off with a timer. However, growers with greenhouses have other methods for keeping their plants in the dark to grow buds.

The art of fooling your cannabis to produce buds early is called light deprivation. This technique can work from a single plant to an entire greenhouse. In regions with a shorter growing season, many greenhouse cultivators will use light deprivation. It is also useful for plants that require more time to flower. For examples, sativas can take up to 90 days in a flowering cycle to finish.

Cannabis usually needs the amount of darkness to be equal to or greater than 12 hours a day to initiate budding. The time in darkness triggers the plants’ flowering cycle. In nature, flowering begins when the days grow shorter and the nights grow longer. Budding can be achieved either naturally or by using blackout materials. The goal is to leave the plants in total darkness and to control them when they flower.

How to use light deprivation

Light deprivation can be achieved with motorized equipment. When set on a timer, the light shade will be drawn evenly across the greenhouse, creating darkness. The material used for shading will depend on the size and setup of your grow, and light deprivation equipment is available many reputable vendors.

Smaller-sized operations may do the work by hand and cover and uncover the greenhouse each day. This daily ritual becomes another task in the long list of things to maintain a healthy and productive garden. However, adding light deprivation to your grow can bring many positive results.

The best practice is to choose the coolest part of the day, either before twilight or dawn, to black out the grow area. Choosing the right time is essential for assuring the health of your grow. Also, airflow is necessary whenever your crop is covered to minimize the risk of molds, mites and heat stress.

Three factors for depriving light

Combining the sun’s full-spectrum energy that plants crave with a few tricks to extend or modify your season puts you in control. The time to start depriving your plants of light depends on three basic factors.

First, know your location and the length of the growing season. Positioning your greenhouse to collect as much full sun throughout the day is crucial. Knowing when seasonal weather changes begin in your area will guide you on when to start your light deprivation cycle. If you are unsure of the outdoor light schedule for your area, consult the Farmer’s Almanac. This is a great resource for determining the position of the sun at any time in your growing season.

Second, know how long your chosen strains take to finish flowering. Understand your climate and the light cycle for the area you’re working in. Keeping a calendar from seed to harvest will give you a good idea of the schedule to follow. Mark upcoming milestones based on your strain genetics, and plan when you want to start your light deprivation according to when you’d like to harvest.

Third, know your greenhouse’s ability to heat the area to extend into the cold season. The type of greenhouse you have or choose to build will dictate how you can use it for light deprivation. If you live in an area with an early winter, such as Washington state or Vermont, heating your greenhouse may be needed for success. Supplemental lighting can also be added to give year-round growing options.

Benefits such as maintaining a standard harvest schedule and having the full time needed to finish all your plants are just a couple of the reasons you may choose light deprivation. With proper planning, this technique will give any greenhouse grower an edge to success.


By Eric Stone
Image Credit:By Quistnix (Own work) [CC1.0 (https://creativecommons.org/licenses/by/1.0/legalcode), via Wikimedia Commons
Cannabis Cultivation Today articles are for informational purposes only and should not be considered legal guidance or advice on grow practices. You should contact an attorney or a qualified cultivation consultant for specific compliance and cultivation advice.
© 2016 CAN Performance Group, LLC. All rights reserved.


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