Cannabis Light Periods

Light schedules are important to cannabis plants.  There are two stages to keep in mind when following light schedules.  The vegetative and the flowering stage.

Cannabis plants will get bigger and bigger with longer days, and will start producing buds when you start giving them longer nights.  Photoperiod plants don’t start budding until they get specific signals from the sun that the winter months are coming.  Ruderalis strains can auto-flower (which can flower without light signals and usually flower withing 3-4 weeks of age).

Vegetative Stage

The vegetative stage is the stage after cannabis plants are seedlings or clones.  During this stage, plants typically get a light cycle of about 18 hours on and 6 hours off.  This mimics the natural light cycle of a cannabis plant in the wild and keeps it from flowering.  However, some plants may stress under strong lighting for 18 hours, so alternatively, you can try a 6 hours on 2 hours off cycle during a 24 hour day, and can be given more intense lighting as an added benefit.  This can also give a break for some cooling in the grow space.  A good rule of thumb is to use 10-20% light wattage in vegetative growth from the wattage used in the flower room.

Grow lights commonly used in vegetative stage:

Flourescents are a great are a choice for clones, young plants, and supplemental lighting, and are cheap to buy, don’t use a lot of electricity, and make less heat, which is beneficial for small spaces.  They have a great light spectrum and are one of the best lights for clones and young plants.

Fluorescent Grow Lights

CFL Lights
CFL Lights produce great spectrum for growing cannabis and can be used in tiny spaces where no other grow lights would fit, such as the inside of a cabinet.

T5 Grow Lights
T5 Grow lights are the most common and available types of grow lights.  They are available in many garden and home improvement stores.  T5 Grow lights are much larger than CFL’s and usually fit into a panel.  They can be kept inches away from plants within burning them.

Flowering Cycle

The flowering cycle can be triggered with 12 hours of darkness.  After plants start flowering, they must continue to get longer dark nights until harvest or can revert back to the vegetative stage.  During the flowering stage, plants are put on a 12 on 12 off schedule to initiate budding.  In the natural outdoors, plants start flowering in the late summer, when nights are longer as winter approaches.  During the 12 on cycle, plants can be given more intense lighting.

Grow lights commonly used in flowering stage:

High Intensity Discharge (HID) Grow Lights

High Intensity Discharge (HID) grow lights are much more efficient and high powered than fluorescent lights.  They are great for growing cannabis, but they are also very hot and need exhaust to help vent out heat.  Some examples are metal halide, high pressure sodium or ceramic metal halide bulbs.

Metal halide bulbs are commonly used in veg stage, as they produce a bluish light and spectrum that veg plants love.

For flowering however, high pressure sodium or ceramic metal halide bulbs are more typically used because they are efficient and their yellow light stimulates flowering.  These lights can get better yields per watt of electricity, more than any other grow light available today.

LED Grow Lights

When using LEDs, the latest models with full spectrum light are your best bet.  Without it full spectrum, plants can become nutrient deficient and don’t grow well.

LED grow lights have become a popular alternative to growers who want an alternative to HPS grow lights, although older models produce slightly smaller yields per watt.   Some growers believe that they help produce more resin in the buds.  They run a little cooler and have built in cooling, although they still produce heat and tend to need more space between the light and the plant; larger versions need exhaust and require ventilation.

The latest full spectrum LED grow lights have been known to produce greater yields, do not flicker, and don’t need to use additional fans since they do not overheat.  They can be used for 50k hours or more and do not need service for years of use.  For more information or the best led grow lights guide or reviews on the latest HPS bulbs, visit website.

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