Why Darkness is Important for Cannabis Plants

Cannabis growers know darkness is as important as light. You may not think of the principles of yin (darkness) and yang (lightness) when planning your light deprivation schedule, but savvy growers understand the dual needs of cannabis. And whether your greenhouse sits in the Pacific Northwest under long summer days or in the hotter climes of the Central Valley, it’s important to balance darkness and light for a maximum bud harvest.

Why is Darkness So Important?

Cannabis is a photoperiodic plant that responds to seasonal changes in light. That means when the days grow shorter, the plant’s life cycle is nearing its end, and flowering occurs for reproduction. In nature, male cannabis sacs release pollen to pollinate female plants in blossom. The result are seeds, which allow the plant to produce a next generation.

As a cultivated plant, cannabis still responds to light changes. Depending upon the strain you’re working with as well as your environmental demands, your light-to-dark ratio will vary a bit. If you’re new to the strain (or growing), talk to old hands about when to end the vegetative phase and trigger your plants’ flowering phase. That timing is critical to maximize your yield. Here are some more specifics.

How Much Darkness is Needed?

The Vegetative Stage of Cannabis

Cannabis in the vegetative stage (when it is growing at a rapid pace) needs at least 13 hours of light per day. In fact, indoor growers commonly use a 18/6 light to dark ratio to encourage faster growth. (Note that most indoor growers vegetate their plants 4 – 8 weeks.)

The Flowering Stage of Cannabis

When you are ready for your cannabis plants to flower, a 12-hours of light and 12-hours of darkness schedule is standard. 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.

Keep to Your Chosen Schedule

If you decide on the classic 12/12 light dep schedule where you cover your plants at 7 p.m. and uncover them at 7 a.m., stick to that schedule. Keep in mind that this schedule requires good ventilation, so some growers choose to uncover their plants at night once the sky is completely dark.

Uninterrupted Darkness

What many growers don’t realize is that cannabis demands an uninterrupted dark cycle. Just as your good REM sleep would be interrupted if a light popped on at 2 a.m., cannabis doesn’t fare well when any light disturbs it during its dark “sleep” cycle. The moon and stars don’t bother cannabis, but any artificial light can stop its bud growth. In fact, light interrupting its dark cycles can make cannabis so stressed and irritable that it can lead to hermaphroditism. That can pollinate females and ruin your plants.

Is there a Way to Simplify Light Deprivation?

Covering and uncovering your greenhouse on a set schedule, day in and day out can be extremely time and labor intensive. Pulling tarps is a lot of work, but using the right tools and products makes all the difference. If there is one product you need to provide ample, reliable darkness for your cannabis, it’s a good deprivation cover. Plus, choosing the right light deprivation materials can help you stay on your light dep schedule, and that will improve your harvest.

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. Plus, the cover can be easily set or lifted with the BOLD EZarm Tarp Puller. The BOLD EZarm allows one person to easily cover and uncover a greenhouse without additional help, making the daily chore of light deprivation so much easier.

Learn how Americover’s BOLD products can help you balance the light and darkness your plants require. Simplify light deprivation. Our experts can at 760.221.6013.