(Continued from page 20
systems, induction fluorescents will not require bulb
replacement for over a decade.
groups of LEDs in a COB system are easier to inte-
grate into an effective horticultural light source. In
fact, 20-50 individual light emitting diodes can be
replaced by a single COB LED. Another advantage of
COB LEDs is a larger surface cooling area, which in-
creases longevity and overall efficiency. Perhaps the
most impressive feature of COB LEDs is their radiant
efficiency. A typical HID (single ended) system has a
radiant efficiency of around 30%. This means roughly
70% of the electricity used by the system is converted
to heat and not into usable light. A COB LED has a
radiant efficiency of 40-50%, which, relatively speak-
ing makes them one of the most efficient artificial
light sources for growing plants.
Sulfur Plasma
Sulfur plasmas are another induction technology
that utilizes a sealed bulb design. The most promising
aspects of sulfur plasmas are they have the intensity
of HID lighting and emit the ideal light spectrum for
plant growth. With CRI ratings of up to 94, sulfur
plasma lighting systems have the closest spectral light
output to that of the sun than any other artificial hor-
ticultural light source. As with HID lighting, cover-
age and plant canopy penetration are not issues for
sulfur plasmas. Another advantage of sulfur plasmas
is longevity. Similar to induction fluorescents, sulfur
plasma lighting can last up to 10 years and will lose
very little PAR and CRI over the course of the fix-
ture’s life span.
LED
Light emitting diodes (LEDs) have come a long
way since they were first introduced to the horti-
cultural industry. The first few generations of horti-
cultural LEDs fell short of meeting the demands of
indoor growers. However, that didn’t stop horticul-
tural LED manufacturers from continuing to develop
more effective and more efficient lighting systems.
One of the biggest breakthroughs for horticultural
LEDs came recently in the form of COB (chips on
board) technology.
In a COB LED system, there are multiple light
emitting diodes packed into a single module. The
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During the next five years we will continue to see
advancements in these horticultural lighting systems.
Highly efficient HID systems, induction fluorescent
light technology, and COB LEDs will all play impor-
tant roles in shaping the future of horticultural light-
ing. For now, indoor horticulturists and greenhouse
growers have the opportunity to test drive some of
these revolutionary lighting systems. A grower should
choose the lighting system technology that will work
the best for him or her, depending on his or her par-
ticular set up and budget.
When examining a lighting system, a good point
of focus is efficiency. Put another way, a grower
should examine the amount of usable light energy
produced versus the amount of electricity used; the
more efficient the lighting system, the higher the
return on investment. Comparing different lighting
technologies can be difficult. Information provided
by lighting manufacturers can be confusing and hard
to compare. All in all, any of the lighting technolo-
gies discussed here will grow plants effectively. Ulti-
mately, it is up to the grower to decide which lighting
system would be the best fit for his or her garden. GG
Eric Hopper resides in Michigan’s beautiful Upper Peninsula where
he enjoys gardening and pursuing sustainability. He is a Garden
& Greenhouse senior editor and can be contacted at Ehop@Garde-
nAndGreenhouse.net.
www.GardenandGreenhouse.net
November 2017