Rooftop Gardening with LEDs

[American Beauty Gardener]

St. Hilda's & Saint Hugh's is an independent, Episcopal school in
New York City that is
devoted to changing the world one child at a time. Children enjoy
organic milk and pesticide
free fruit. Food is purchased from local vendors so as not to
contribute to the
environmental impact of shipping food across country. Solar-powered
sensor-activated
hand washing sinks are available alongside the waterless urinals and
dual flush toilets. Their
2.5 million dollar renovation utilized recycled, natural, non-toxic,
and renewable materials.
These changes and more have made them one of the first schools in New
York City to
reduce their annual electricity related carbon emissions by 100%,
saving the city
approximately 376 tons of emissions per year. St. Hilda's & Saint
Hugh's is not stopping
there.
In the past, school greenhouses have been limited to operation in
the spring and fall
simply because many areas in the United States do not have a natural
photoperiod that will
support growth year round. Safety issues prevented the use of
traditional greenhouse
lighting as a supplement. As a general rule of thumb- schools do not
mix children and hot,
fragile, high voltage devices that contain lead and mercury.
The safety and efficiency of LED Grow Master lighting has made it the
perfect choice for
St. Hilda's & St. Hughs to extend the photoperiod for year round
gardening. Toddlers
through eighth graders will soon be enjoying their own greenhouse
located on the rooftop
high above the busy streets below. Scheduled for completion later
this month, the
greenhouse will be an extension of their science curriculum.
Cucumbers, tomatoes, sprouts,
and other fruits and vegetables will be grown by the children and then
made available in the
cafeteria's salad bar. Providing the students with hands-on experience
of how their food
comes to the table, as well as the satisfaction and delight that come
from eating the fruits of
their labor.-AL

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Vertically Stacked Planting Beds
Using LEDs as a plant growing light source reduces the distance
between the planting bed
and the lights, allowing more efficient use of the available growing
chamber volume. Using
LED Grow Master grow bars as the plant light source, it is possible to
employ up to three
or more vertical layers of planting beds in the area now being used by
each single planting
bed. This would effectively at least triple the biomass production of
the growth area.
The low heat output of LEDs makes this further feasible. HID
lighting operates at
temperatures above 1000 degrees Fahrenheit. Which is why adding an
additional layer to a
grow chamber utilizing this light would make the heat unmanageable.
LED Grow Master
lighting operates at less than 15 degrees above ambient temperatures
so they will not
overheat the area or burn plants and people.
Farmland is shrinking and the number of people to feed is growing.
Why not turn that
wasted four feet at the top of your grow space into a second crop? The
technology is here,
and you know what they say... "Waste not, want not."--AL

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Determining the Mounting Height
We have developed general guidelines to follow when hanging the
LEDs. For instance,
a single LGM5 should be mounted 28-18" from the top or sides of your
plants. One of the
few common characteristics of traditional lighting and LED lighting is
that they both follow
the Inverse Square law for light intensity. The light intensity
decreases as the square of the
distance from the light. For example, an LGM5 hung at 36" will have
approximately 1/4 of
the intensity of the LGM5 at 18". This is a large range of light
intensity that enables
growers to adjust for the needs of different plants. Because 100% of
the light emitted is
being used by your plants (as opposed to 10% of the light from
traditional lighting) there is
a danger of giving your plants too much light.
Hanging the bar further away will increase your coverage area but
decrease the
intensity. Hanging the bar closer will decrease your coverage area
but increase your light
intensity. The exact mounting height that will satisfy your plant's
light requirements can
only be judged by observing your plants reaction to the light, and of
course, good old
fashioned common sense. Changes in light intensity should be
gradual. A plant that
naturally grows in the deep shade of the rainforest will likely suffer
if an LGM5 is placed at
20 inches over the plant. A plant that naturally grows in the bright
sunlight may thrive at 20
inches. Like all light sources, the bars will need to be raised to
maintain this distance from
the plant.
Remember that plants will generally survive a period of low light
but too much light
may permanently damage them. This is why we recommend that you start
your bars off
close to the maximum distance recommended and then watch for signs to
determine if the
bars should be lowered. If you have a nearby window and you see your
plants leaning
toward the window you may want to lower the bar. If there is not
another light source and
the plants are leaning away from the LEDs it could be a sign that they
are getting too much
light. Not enough light will cause leaves to turn yellow but too much
light will bleach the
leaves. If the bar needs to be closer you may see reduced leaf size
and longer internodal
lengths. If upward growth stops the lights should likely be raised.
Once you have
determined a distance that is promoting the vigorous growth you are
looking for you can
assume that this is the optimal mounting height.