Why Darkness is Important for Cannabis Plants

Most cannabis growers know that darkness is just as important as light to plant growth. While greenhouse growers in California and the Pacific Northwest are able to take advantage of the long summer days to yield two or even three harvests out of the season, it’s still darkness that helps the cannabis flourish. Christopher Teague, in Herb Magazine explains the science behind this phenomenon in detail. Here are a couple key takeaways from his article.

Cannabis Needs Darkness to Grow Buds

Cannabis in the vegetative stage (when it is growing at a rapid pace) needs at least 13 hours of light per day. When cannabis reaches the flowering stage, the light is reduced to 12 hours on/12 hours off. Nighttime provides darkness, keeping cannabis on somewhat of a natural clock. This is why indoor growers need to make a deliberate effort to not only create long, bright days, but also emulate dark cycles in order for cannabis to grow large full buds.

Not Just Darkness, but Uninterrupted Darkness

What many growers don’t realize is that cannabis is very finicky about the darkness it receives. The same way you wouldn’t want the sun to peak through unexpectedly at 2 a.m. while you were sleeping, cannabis doesn’t want any hint of light seeping through during its dark or “sleep” cycle. The moon and stars don’t bother cannabis, but just about any manufactured light or sliver of sunlight will.

According to Teague, “a strong enough exposure during their night cycle can trigger them to stop growing buds and revert back to vegetative growth.” Additionally, cannabis will get irritable and stressed if its sleep is disrupted. This could potentially lead to a hermaphrodite, which poses the danger of pollinating females and killing your entire crop.

The Best Way to Keep Light Out During Dark Cycles

If there is one product you need to provide ample, reliable darkness for your cannabis, it’s a deprivation cover.

Americover’s BOLD® Black Out Light Deprivation Tarp is the top-selling greenhouse cover of its kind nationwide, consisting of two sheets of high strength virgin polyethylene film laminated together with a third layer of molten polyethylene. The cover is scrim reinforced for superior tear resistance and can be easily set or lifted with the BOLD EZarm. To learn more, click here.