What is a light DEP greenhouse?

What does Light DEP mean?

For people who grow cannabis, most know that at light deprivation AKA light dep greenhouse is one that artificially controls the amount of light that the plants inside a greenhouse receive.Light deprivation dictates who often and how much light the plant receives. This is done by pulling a cover over the greenhouse to block the sunlight from entering the greenhouse. The covers can be pulled manually or automatically.

The reason behind using a light dep system is because by doing so it allows the grower to produce denser flowers by timing the flowering period. When growers us automated systems there is no mistaking at what time the cover needs to be applied.

Additionally, when light deprivation is used for growing cannabis, multiple harvests can be obtained by essentially forcing your plants to flower early. All of this translates to an increase in profits. If you grow both inside and outside you can stagger when you have your plants flowering.

Are Cannabis Plants the Only Plants That Use Light Dep Greenhouses?

NO! Zinnias, Asters, Mums, Poinsettias, Christmas Cactus, and Cosmos all benefit from light deprivation growing.


Light dep greenhouse for poinsettias

Prime bloom time for poinsettias occurs in October through December. These plants initiate flowering after experiencing 12 hours and 20 minutes of uninterrupted darkness for five straight days. The dainty, inconspicuous yellow flowers will appear 65-85 days later.

In February and March, poinsettia plants naturally begin to drop their leaves, which are replaced by new growth a little later in the spring. During April and May, poinsettias are actually green all over. It’s not until the shorter days of winter that the upper leaves turn red. The plants experience color changes once being subjected to about 10 weeks consisting of days with 12 hours or less of daylight.


Light deprivation greenhouse for mums

Mums also flower when nights become longer. It takes 9 1/2 hours of darkness for flower buds to form and more than 10 1/2 hours to begin flowering. When growing mums, the industry standard suggests the plant needs 12 hours of darkness to develop flowers.

Different cultivars need shorter or longer periods to complete flower formation. Cultivars are classified as 7-through-10-week-response plants. Based on their classification, once light dep is initiated, they can take six to ten weeks to form flowers.


Cannabis naturally reaches its peak flowering cycle during the transition from summer to fall, when the days shorten. Drastic dips in temperature can often inhibit flowers from expanding to their full potential. By tricking the plants into thinking that the seasons are changing, cannabis will begin to flower.

A 12/12 light deprivation cycle is the most common procedure in cannabis growing; 12/12 means your plants receive 12 hours of daylight and 12 hours of darkness. As an example, a grower who is doing manual light deprivation has to be ready to cover his plants or roll down his tarps at 7:00 PM and then be ready to uncover every morning at 7:00 AM. Timing is everything. Growers who use automated controllers in their greenhouse operations simply program the desired times and the work is done for them.

In a greenhouse, controlling light is not the only factor that attributes to healthy crops. During periods of “blackout,” high levels of heat and moisture can build up inside your greenhouse.This can lead to nutrient deficiencies, pest infestation, fungus growth, mold, etc. By using automatic controllers to operate your light dep cycles, controlled air flow systems and proper dehumidification systems,  you can monitor and set limitations for humidity and temperature.

A plant’s tendency to flower is triggered by phototropism, the natural reaction to changes in available light. As seasons transition, the change in the amount of available daylight will encourage plants to flower. Short-day plants initiate flowering during late summer and early fall when the amount of daylight decreases. Long-day plants begin to flower when days grow longer during Spring. Forcing plants to flower early can help with multiple crop programs.  Rather than waiting for mother nature and timing to dictate when things go into flower, Your light Deprivation system can help accelerate this process.  This accelerates your grow program, which could increase profits, reduce wait time and provide a more smooth continuous stream of your  "product".  

Light deprivation techniques allow growers to manipulate nature and artificially control flowering cycles. With cannabis, effective use of light deprivation can increase the yield per plant and harvest frequency. For crops like poinsettias and chrysanthemums, light deprivation accelerates maturity, thereby enhancing a crop’s value.


Please note that Hemp and marijuana are, taxonomically speaking, the same plant; they are different names for the same genus (Cannabis) and species. 

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