Optimize Cannabis Growth with the Right Lighting Schedule

The Science Behind Light and Dark – Cannabis lighting schedule

All cannabis plants have special sensors for sense the lights. When these plants are kept in the dark for a long time, they decide it’s time to start making flowers.

This switch to flower-making is a slow process, and it only works if the plants get total darkness. If they see any light during this time, they’ll stop making flowers and go back to just growing leaves.

That’s why it’s super important to give flowering cannabis plants a solid 12 hours of complete darkness. This darkness not only tells the plant it’s time to make flowers but also helps them enhances trichrome production.

Dark Cycles for Growing Cannabis

Just as important as watering your plant is the amount of light and darkness it gets.

The amount of darkness a cannabis plant needs is directly related to its growth cycle. For instance, during the flowering stage, cannabis needs more darkness compared to the vegetative growth stage.

Interestingly, the key to growing cannabis well has more to do with the dark cycle than with light.

Controlling the dark and light cycles is much easier when growing indoors. Mimicking nature, where shorter days in late summer signal cannabis plants to start flowering, allows us to encourage our plants to bloom by reducing the light duration to 12/12 indoors.

Seedlings and Cuttings

Seedlings and cuttings have special needs. They thrive best with about sixteen to eighteen hours of light each day. However, it’s essential that this light is not too strong. It should be diffused or spread out, so it’s not too harsh on them.

As your plants grow and you can see three to four nodes (the points where leaves grow from the stem), you can give them more direct light. At this stage, they enter the vegetative growth phase, which is when they start to develop into mature plants.

Vegetative Growth Phase

During the vegetative growth stage, plants need 18 to 24 hours of light to make sure they produce enough roots, leaves, stems. In this phase, plants build strong roots and stems, and they grow more leaves for taking in more nutrients, water, and light. The leaves use sunlight to make sugars through photosynthesis, which feeds the plant.

Sunlight gives plants a complete range of light, containing lots of blue light. You can accelerate plant growth in the vegetative stage by providing constant light for 24 hours without any dark period.

While some growers like keeping the light on all the time, others choose to give their plants a break with some “rest” or dark time. Providing 18 hours of light and six hours of darkness not only saves on electricity but also reduces related costs.

Flowering Growth Phase

Plants which are ready for going into flowering stage require 12 hours of darkness and 12 hours of light to start produce flowers. The dark stage is critical to keeping plants flowering and should not be interrupted. For plants grown indoors, it is easy to control the dark and light cycle with the use of a light timer.

Timers can be set to automatically turn the lights on and off. The flowering phase lasts anywhere between 8 to 12 weeks depending on the strain of cannabis. Sativa strains generally take longer to flower.
When plants enter the flowering stage, they start using water and nutrients differently. Instead of focusing on growing taller or getting more leaves, the plant shifts its attention to making dense flowers.

Don’t Forget the Total Darkness

No matter what light source used for growing cannabis, plants require 12 hours of total darkness for flowering. During this period darkness becomes more critical to the plant than light. Try to find out all the light sources and eliminate them. Even the small green light on your Air Con or Humidifier can interrupt the complete darkness!