Professional Marijuana Grower September-October 2017 Issue | Page 24
it enters the flowering stage. Some growers will increase
the light energy incrementally as the plant grows in the
flowering stage, but many growers find that starting with
the higher light intensity (corresponding to the plant’s
finishing size) so the plants can “grow into” the space is
the most effective way to achieve the best results.
Another aspect of lighting intensity is the distance be-
tween the artificial light source and the top of the plant
canopy. The inverse square law states that the farther
light travels from its source, the more it diminishes. Put
another way, when the plant canopy is farther away
from the light source there is less usable light energy
available to the plants. However, due to the extreme heat
and intensity of some artificial light sources, plants can
become damaged if they are placed too close to the light
source. The best way for a grower to make the most ef-
ficient use of his or her available light energy is to place
the plants as close to the light source as possible without
causing damage to the plants. Bleached or white flower
tops are strong indicators that the plants are getting
“over saturated” and are too close to the light source.
Artificial Light Technologies for Flowering
Marijuana
There are a few different light technologies that can be
used successfully to flower cannabis plants. Each technol-
ogy offers its own advantages and disadvantages. Some
garden set ups are simply more compatible with certain
lighting technologies than others. In fact, the grow room
and the type of growing system being used are both key
factors when determining which lighting system would be
the most efficient choice.
High Intensity Discharge (HID)
High intensity discharge lighting includes both metal ha-
lide (MH) and high pressure sodium (HPS). HID lighting
consists of three components: the ballast, the reflector or
socket, and the bulb. Ballasts can be specific to the type
of bulb (MH only or HPS only) or they can be switchable,
or “smart” ballasts, and have the ability to operate either
type of bulb. There are also double ended HID bulbs
which have increased efficiency and longevity over other
bulbs in the HID category.
HID lighting is still the most popular choice for flowering
cannabis for a few reasons. First, this technology has
been around for a long time and is used in other indus-
tries. This means there are many manufacturers which
helps lower the cost and creates newer, more efficient de-
signs. Initial cost and reliability are not the only reasons
marijuana growers continue to choose HID lighting. High
wattage HID fixtures are very intense and are capable of
penetrating deep into a plant canopy while also cover-
ing a large area. Due to state regulations, many medical
marijuana growers are allowed a limited number of
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24 • Professional Marijuana Grower
SEPTEMBER/OCTOBER 2017