Plant growth involves the conversion of light energy into
plant-building materials (photosynthesis, see chapter 2). Two
factors are important for optimal growth. In the first place, the
light intensity. Light intensity is expressed in 'lumens'. At
least 50,000 lumens are needed for growing indoors. It's not
sufficient to add up the number of lumens listed by the
manufacturer for each lamp. The total number of lumens given off
is depends strongly upon good reflection, and proper connecting
fixtures and starter ballasts for the lamps. The quality of the
reflector used, and the connecting fixtures and ballasts
determine the light yield for the greatest extent. For those
reasons, self-built sets and home-designed illumination often
deliver a lot less light yield than lamps being used in
professional horticulture. We can improve the light yield in our
grow room by applying reflective material. We haven't painted the
walls of the room matt white, and used reflector caps for the
lamps for nothing! The second important factor is the wavelength
of the light. For the production of chlorophyll, and an optimum
photosynthetic reaction, light from the blue spectrum (445
nanometers), and light from the red spectrum (650 nanometers) is
necessary. Blue light ensures optimal phototropism. Phototropism
is the phenomenon which causes plants to grow towards the light,
and to spread their leaves in such a way to receive the most
light.
4.2. Choices for lamps
In this book, we prefer high-pressure sodium lamps, and
mercury-iodide lamps for illumination. Ordinary light bulbs are
not suited for cannabis-growing due to their considerably short
life span, and principally due to their low light yield. Halogen
lamps are not advisable for the same reasons. Fluorescent lamps
are not appropriate for home growing. They do serve well,
however, to stimulate seedlings and cuttings to set root. For
actual growing, we stick to gas discharge lamps in the form of
high-pressure- sodium, and mercury-iodide lamps. There are lamps
being sold which emit both the wavelengths needed (blue and red)
but we prefer installing seperate lamps in a 1:3 proportion (1
lamp for blue light with 3 for red light). The combination lamps
give off a lower amount of lumens, since they have to emit
different wavelengths. This counts for growing: the more lumens,
the greater the yield. This doesn't mean we can install an
unlimited number of lamps. Other factors must be considered.
Using many lamps means a higher temperature (the heat must be
discharged of), a greater need for fresh air (containing CO2),
and a greater need for water and feeding. Always remember the law
of minimums Depending on the size of the garden, we use 400 Watt
lamps or 600 Watt lamps. This choice is made in such a way that
all the plants in the garden area can be illuminated as evenly as
possible. By using 400 W lamps, you can put up one-and-a-half
times as many lamps for the same electricity use as when using
600 watt lamps.Also 1000 watt lamps are being sold but proper
reflectors for these types of lamps are not available. The result
is a disproportionately large loss of yield. Moreover, 1000 Watt
lamps give off more heat. Therefor they must be hung high above
the plants, and this means more loss of light yield plays in the
question. 1000 Watt lamps, with respect to 400 and 600 Watt
lamps, mostly cause pain in your wallet, because the electricity
bill gets higher.
In practice, it is possible to reach a light yield of 70-90% of
the lumens which are emitted. For that, (it can't be stressed
enough), good reflection is necessary. Below is a chart with data
for several reflective materials: Reflectivity in % - Reflective
plastic sheet 90-95 - matt white paint 85-90 - semi-matt white
paint 75-80 - matt yellow paint 70-80 - Aluminium foil 70-75 -
Black paint less than 10 Using proper reflective material, proper
connecting fixtures ballast equipment, proper reflector caps with
the lamps, and a distance from the lamps to the plants of 40 to
60 centimeters, 400 Watt lamps deliver, on average, between
35,000 and 47,500 lumens, and 600 Watt lamps between 60,000 and
80,000 lumens (at a distance of 50-70 centimeters). The distance
between the plants and the lamps differs because 600 W lamps give
off more heat. Ifthe plants are to close to the lamps, they will
dry out and burn 600 Watt lamps are preferred, because you get
the highest light yield for the lowest electricity cost. Though
they do require more careful climate control The life span of a
high-pressure gas lamp is approximately 2 years when it's used 18
hours a day. The lamps are, however, subject to decay, which
lessens the light yield.
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In practice, it appears that high-pressure gas lamps give optimal
results for 4 to 5 harvests. After those, it's advisable to
replace them. It seems that the installation of one 600 Watt
sodium lamp per square meter is enough to achieve the best
results. Principally one can say 'the more light, the better',
but with more illumination, the control of other factors (namely,
temperature control) becomes a problem. Indoor growers work with
their light source close to the plants. Considering the light
yield of the sun, (hundreds of thousands of lumens, but a little
further away), fewer lumens are needed for growing indoors. A
simple formula shows that you can also use three 400 W lamps for
two square meters. The sodium lamps provide light from the red
spectrum. This light is used principally during growth. A
mercury-iodide lamp fills in the blue spectrum. For reflection,
growers use wide-angle reflectors with sodium lamps, and
super-wide-angle reflectors with mercury-iodide lamps.
Super-wide-angle reflectors spread the light over a greater
surface area. We use the proportions of 3 red lights to 1 blue.
So, the light from the blue lamp must be spread over a larger
surface area.
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4.3. Using high-pressure gas lamps
High-pressure gas lamps may only be used in the fitting meant
for that particular lamp type. High-pressure gas lamps all have
their own start-up conditions, voltages, characteristics, and
shapes. Using lamps with improper sockets can cause electrical
shorts! Therefore, it's recommended that you buy all the parts of
a pressurized gas lamp from the same dis- tributor. The sockets,
ballasts, and connectors must always be protected from humidity;
otherwise, electrical shorts occur. As stated earlier,
high-pressure gas lamps have a long life span. You must be
careful when replacing these lamps. They are, as the name
implies, under pressure, and they explode when you destroy them.
When you do that yourself, you must always wear gloves and safety
glasses. In addition, you have to protect yourself against the
poisonous materials found in these kinds of lamps. The heat given
off by high-pressure gas lamps, and their accompanying starter
ballasts, must be completely ventilated. This means that the
lamps shouldn't hang too close to the plants (hence drying and
burning occurs), but also not too close to (flammable) ceilings
and walls. Place a piece of non-flammable material (not
asbestos!) between the lamp and ceiling or wall. Furthermore t's
necessary to discharge of excess heat by using a ventilator.
Finally, it's important to keep high-pressure gas lamps clean.
Dirty lamps provide much less light yield than clean ones. The
lamps should be polished now and then with some glass- cleaning
agent. That should be done only when the lamps are turned off,
and well-cooled.
the use of gloves to protect the lightbulb cloning
accessories
Be especially careful with water. Lamps which are still hot, or
even warm, can explode when touched, and that's not funny Also,
take care never to touch these types of lamps with your fingers.
Just like halogen lamps, bodily acids can burn through, causing
the lamp to fly to pieces.
4.4. Proper lighting for cannabis
The advantage of growing cannabis indoors is the fact that
you can give the plants the feeling that it's their flowering
season all year round. You're not dependent on the weather or the
season. We distinguish two separate phases in plant cultivation:
the growth- or vegetative phase, and the flowering- or generative
phase. We've already made sure the lamps are installed in such a
way that all the plants can be optimally illuminated. A light
period of 18 hours and a dark period of 6 hours is ideal for the
vegetative phase. We're assuming that you already have cuttings
with roots. With proper care, a healthy cannabis plant can grow
up to 5 centimeters per day. It's very easy to cause the plant to
flower. We only have to give the plants the idea that the days
are getting shorter ('autumn'; for cannabis, the sign to flower).
We do that by making the light and the dark periods the same
length; - 12 hours. In principle, cannabis is an annual plant.
The entire life cycle, from seed to death, takes place in one
year in nature. When growing cannabis under artificial light, it
is possible to force flowering earlier than in nature. After 4 or
5 days vegetative phase, flowering can be 'provoked'. We do that
the moment the clones have visibly started to grow. Two or three
weeks after the light period is reduced to 12 hours, the plants
begin to flower. It's very important not to interrupt the dark
period. If the plants receive light during the 12-hour dark
period, they 'get confused'; they want to continue growing, and
the blooming phase is postponed. The generative phase lasts 60
days or longer, depending on the variety you're growing. When
working with cuttings, it's possible to harvest four to five
times a year.
the cutting or clipping of a clone and the motherplant and its
clone on a rockwool plug.
watertank
with the needed accesories
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