The best light for the job
Once you are out of the seedling or
cloning stage, you will want the best
lights for producing leaf growth. T5s
and metal-halide lights are the first two
choices for top-notch vegetative plants.
When choosing a T5 fixture, pick the
units in accordance to the size of your
garden. If you are growing in more
than a 2-ft. by 4-ft. area, get a 4-ft. T5
with eight tubes. In other words, get a
2-ft. by 4-ft. T5 light to cover a 2-ft. by
4-ft. area. Here are the coverage areas
for the most common T5 fixtures:
4-lamp, 2-ft. T5 = 1-ft. x 2-ft. vegetative garden
4-lamp, 4-ft. T5 = 1-ft. x 4-ft. vegetative garden
8-lamp, 2-ft. T5 = 2-ft. x 2-ft. vegetative garden
8-lamp, 4-ft. T5 = 2-ft. x 4-ft. vegetative garden
When choosing a metal-halide light,
you can expect the following coverage:
250-W metal halide = 2-ft. by 2-ft. vegetative garden
400-W metal halide = 3-ft. by 3-ft. vegetative garden
600-W metal halide = 4-ft. by 4-ft. vegetative garden
1,000-W metal halide + light mover
= 4-ft. by 8-ft. vegetative garden
With these lighting recommendations, you can expect up to 18 in. of
leaf and stem growth. If you are trying
to grow taller vegetative plants, go
with a 1,000-W light over a 4-ft. by 4-ft.
garden. With that kind of intensity, you
could produce 5-ft.-tall tomato plants
and get a jump start on the outdoor
garden season. Fruiting and flowering
(the reproductive phase) is the goal for
many indoor gardeners. For plants to
achieve the same kind of growth made
possible by the sun, some serious intensity during the fruiting and flowering
stages will be required.
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Maximum Yield USA | February 2014
High-Pressure Sodium Lights (HPS)
Other Lamp Technologies
HPS lights continue to produce excellent results for those seeking both quality and yield. When operating a large
flowering room with multiple lights,
some growers prefer a mix of metalhalide and high-pressure sodium lamps
for a mixed spectrum. Metal-halide
lamps will grow healthy flowering
plants, but the yield is slightly reduced
compared to HPS. When using HPS
light for flowering indoors, go with the
following guidelines for matching the
right light to your garden:
Light-Emitting Diodes (LEDs)
400-W HPS = 2-ft. by 2-ft. flowering garden
600-W HPS = 3-ft. by 3-ft. flowering garden
1,000-W HPS = 4-ft. by 4-ft. flowering garden
While HPS lights can produce healthy
plants over larger areas than suggested
here, the plants themselves will be
reduced in size. Spreading the light
over a larger area tends to get a similar
yield with lower quality and smaller
individual fruit size. By keeping the
lighting at maximum intensity, you will
get the highest yield for the amount of
space you are using.
LED lights have become common
for gardeners these days. Unfortunately, many failures in the growroom have been attributed to
low-quality LEDs sought by bargain
hunters. High-quality LED grow
lights do exist from a few companies. LED technology offers benefits
including reduced heat, reduced
electrical usage and no bulbs to
replace. For growers who are used
to the performance of a 1,000-W
HPS over a 4-ft. by 4-ft. garden,
you will need to spend $2,000 to
$4,000 to get the same results with
LEDs. That 1,000-W HPS light
would cost more like $300 to $600.
In the long term, LED lights could
be the better choice, as long as you
can afford top-of-the-line units.
The electrical savings, especially
during hot summer months, will
add up over a few years. If you plan
on gardening for a long time, your
LED lights could eventually pay for
themselves with the savings on your
power bills.
For plants to achieve the same
kind of growth made possible by
the sun, some serious intensity
during the fruiting and flowering
stages will be required."