I agree with Dale on terrarium size and the use of four-foot tubes; longer
tubes are more effiecient at making light than shorter ones, so two 24" tubes
do not equal the light output of a single 48" tube. At each end of the tube
the output of light drops off and so having tubes that hang over the ends of
your terrarium would be better than having shorter lights inside.
>Also you don't need to use grow lights. Infact, using only grow lights will
only cost you >more. A mixture, 1/2 and 1/2 using cool whites and
grow-tubes, would be better.
I have grown plants under lights for more than twenty years and, in my
experience, Gro-Lux WS, or better, Vita-lites are well worth the extra
expence; They last longer, have a better light to work under, produce
stronger plants with more red, and promote flowering.
While flourescent lights might seem bright to our eyes, to a plant they are
not very. Over the years have come to realize that I really could not give my
plants too much light. In my growing areas there are two four foot tubes over
every eight inches ( 19 cm. ) of growing area width; over an area 27" wide I
have eight four foot tubes.
The plants should be as close as possible to the light source, their tops
can be about 4 - 6 " under the tubes. Any surfaces in the terrarium that can
be, ought to be painted with white paint to reflect light or coated with
reflective mylar.
You can help to make up for lower intensity light by increasing the duration
of light during the day; you may want to keep the light on for fourteen to
sixteen hours each day and while this isn't normal, plants seen to do better
than with shorter days. Flowering in many plants will be affected by the long
days, but don't worry about it for the time being.
With age, the tubes loose a significant amount of their light output; I
replace the Gro-Lux tubes every year. Vita-Lites are much longer lasting and
they are guaranteed to have 90% of their output after two years - this makes
them actually cheaper to use than Gro-Lux. You may want to use a permanent
marking pen to write on the end of each tube the date that you install the
tube. This helps remind you when to replace them as they still will appear to
be working, but their light will have diminished. I find plants have good
color and flower well under a mix of two Vita-Lite tubes to one Gro-Lux wide
spectrum. The usually reccomended mix of warm white to cool white tubes 1:1
does not produce the same quality of light or the quality of growth (
although it costs about a fifth of what Vita-Lites cost ).
Other factors to consider are anything that may decrease the light reaching
the plants, such as dust on the tubes themselves, glass and plastic barriers,
and foliage in the way.
>> 2) some people, I'm not one of them, have had trouble with their
>plexiglass warping in the humidity and heat.
Plexiglass is not a very wise choice for construction of Terraria - it
yellows, scratches, warps, and is highly flamable. It does not transmit very
much light either, so natural light from the windows won't get through as
well. Its easy to silicone glass to an angle-iron frame, or use a wooden
frame and plastic film. I use a cheap shower curtain, and replace it if it
gets ugly. A fan should be installed inside the terrarium to aid in air
circulation ( and fungus prevention ). To keep the heat from the light from
being trapped inside the terrarium, the ballasts can be "remoted" or located
outside the fixture and placed in an area where the heat can easily
dissipate. In fact, I have seen clever adaptations by growers who use the
ballasts as a heat source to warm propagation areas and growing areas on
demand. If your not confidant with wiring diagrams, you will want an
electrician ( or model railroad enthusiast ) to remote the ballasts for you.
It might seem like a lot of bother, but a well-constructed growing area will
serve you and your plants in a mutually satisfying way for years. Built it
right.
Good Luck and
Cheers,
David