ENERGY SUPPLY OF THE PLANT
Every living creature needs energy to live, develop and grow.
For most living creatures the most important energy source is
sugar (glucose). Green plants are the only ones capable of producing
these sugars themselves. These sugars are produced from water,
which is being absorbed through the roots and carbon dioxide,
which is being absorbed from the air. In order to make sugar
out of these matters, the plant needs light. This process takes
place in the green pigment, (chloroplasts) and is called; photo
synthesis. (photo=light, synthesis=produce, therefore photo synthesis
means; produce through light).
As above, the plant needs light for its energy supply. Because
we are talking about growing indoors, we will have to supply a
light source. Normal lamps are less suitable for the job. A
plant needs light of certain wavelengths, which are not or not
present or strong enough in normal lamps. The Highlife Co. recommends
the use of type SON T lamps. They are suitable for both the growth
stage, as well as the flowering stage. Ballast's are necessary
for these lamps. Ballast's of 600 watts have the most favourable
output of delivered light per watt. Depending on the variety
we recommend to use between 400 and 800 watts per m2. With insufficient
light the plant remains light-green in colour and becomes unnaturally
thin and protracted. The buds will also remain smaller with insufficient
Saving on light is stealing from yourself!.
The efficiency of the lighting in the grow room can be strongly
increased by covering your grow room with reflective materials.
You could paint the walls with mat white paint or cover the walls
with white plastic. Ensure that the room can be easily cleaned
because spraying might pollute the walls quite a bit. Most sorts
of your "favourite plants" remain in their vegetative
(grow) state when the light cycle is maintained at 18 hours.
Your "favourite plant" is a so called short day plant,
in this we mean that the plant will start flowering when we shorten
the light period. Plants are initiated into the flowering phase
by shortening the day period to 12 hours on and 12 hours off per
24 hours. Your "favourite plants" that originate
from the tropics do not react to changing day lengths but flower
after a certain time. That is logical if you realise that a day
in the tropics lasts approximately 12 hours the whole year round.
The lamp must hang at a distance from the plants that will not
cause any scorching of the leaves. This distance differs with
the wattage of the lamp. We recommend a distance of: 400 Watt-
45 cm; 600 Watt- 85 cm; 1000 Watt- 105 cm. Don't hang the lamp
any higher above the plants than necessary.
Carbon dioxide is absorbed by the plant through its pores. In
small spaces, the present carbon dioxide will soon be used up.
Therefore the air in the growroom has to be replenished regularly.
For this you need to buy an exhaust fan. You have to make sure
however that it is powerful enough to replenish all the air at
least 20 times per hour. The fan can be connected to a time clock
or thermostat and/or hygrometer. To provide for an optimal gas
change for the plant we also recommend to place an oscillating
fan in the growroom, in order to have a constant air flow along
In urban areas the carbon dioxide concentration might increase
to a higher value than the normal 0.03% which is 300 ppm (parts
per million). From regular horticulture we know that adding extra
carbon dioxide to a concentration of 0.15% highly stimulates the
growth and the speed of photo-synthesis. This results in faster
and higher yields. This yield increasing effect is most powerful
with intensive lighting and inert substrate cultivation, such
as rockwool. Another effect that has been reported by growers
is the fact that a higher carbon dioxide concentration makes the
plants less sensitive to higher temperatures.
A third effect is that there is less need to ventilate (unless
the humidity is too high) because you don t depend on carbon dioxide
from the outside air. In greenhouses the exhaust gas of oil-fired
central heating is conducted back into the greenhouse. To raise
the carbon dioxide concentration in grow rooms, it is usually
supplied from bottles. There are two ways to provide for more
carbon dioxide in the growroom.
(I) The cheapest way is to buy a pressure regulator that can be
adjusted so that after ventilation (when carbon dioxide is dispelled
from the room) the right amount of carbon dioxide will be released
inside again. The exact quantity you need is something you have
to work out yourself. You calculate this as follows: Length x
Width x Height of the growroom in metres gives the volume of the
room in cubic metres. One cubic metre is 1000 litres. If for
instance you want to increase the concentration from 0.03% to
the required level of 0.15%, you need to add 0.12% carbon dioxide.
Suppose your grow room measures 2 x 2 x 3m , which is 12000 litres.
0.12% of 12000 litres is 14.4 litres. So to this room, 14.4 litres
of carbon dioxide should be added to obtain an optimal gas concentration.
This needs to be done after every exhaust period. This only
needs to be done during the "day period", because the
plants only use carbon dioxide when the light is on. One kilo
of carbon dioxide is approximately 500 litres. So a 10 kilogram
bottle contains approximately 5000 litres. This means that a
grow room of 2 x 2 x 3m needs two bottles per grow period.
(II) The second system to keep the concentration of carbon dioxide
at the right percentage is by the use of a carbon dioxide meter
and a computer controlled pressure regulator. The concentration
of gas is constantly measured and the computer makes sure that
with a too low concentration, the right quantity of gas is added.
The ventilator could also be connected to this computer. This
system is not cheap but once it has been installed you don't need
to worry about it anymore.
The recommended day temperature with the cultivation of your "favourite
plant" lies between 25 and 28 deg C. With higher temperatures
the growth will slow down and the yield and quality will decrease
(many growers experience this during summer). In the dark, other
chemical reactions occur in the plant than in daytime. A lower
temperature suits them best. The recommended night temperature
lies between 15 and 20 deg C. With temperatures lower than
15 deg C the growth is obstructed, lower than 10 deg C the
growth stagnates and lower than 5 deg C will damage the plant.
The most ideal situation would be a grow room with both heating
The roots are especially sensitive to low temperatures. The absorption
of nutrients through the roots is an active process. This means
that the root needs energy to absorb the nutrients, but also to
be able to select these nutrients. The root can, to a certain
point, choose which and how much nutrient it absorbs. This process
can be seriously disturbed with too low a temperature, because
then there is insufficient energy available for this process.
Therefore you have to make sure that when watering the plants
the water is approximately 23 deg C. With cultivation on rockwool
the nutrient solution temperature is held constant with the use
of a special twin glass sleeved aquarium heater that has a built-in
It speaks for itself that the plant must receive enough water.
Don't forget that the water needs of a plant, in time, can strongly
differ. Freshly transplanted seedlings and cuttings require less
water than a flowering adult plant. It is of great importance
that the plant has a well developed and healthy set of roots for
the optimal absorption of water (and the nutrients that will be
mentioned here after).
Most of the water absorbed by the plant is evaporated via the
leaves. By doing so the air in the grow room becomes humid.
The humidity will decrease because of the ventilation in the grow
room. To measure the humidity , you need a hygrometer. A high
relative humidity is very important for the seedlings in the beginning
of the cycle (between 60% and 75%). At the end it is important
to keep the RH low (40% to 50%) because it could cause the buds
to rot. If the humidity is too high, you need to exhaust more
air. If the humidity is too low you could first try to increase
it by hanging some wet (clean!) towels or sheets in the room and
by often spraying the underside of the leaves (normal tap water).
If this is not sufficient you might consider buying a humidifier.
Nutrients in General:
For the healthy development of a plant a number of nutrients are
indispensable. The following elements are necessary: carbon, hydrogen,
oxygen, nitrogen, phosphorus, sulphur, potassium, calcium, magnesium,
iron, manganese, copper, zinc, molybdenum, borium and chlorine.
Carbon is being absorbed through carbon dioxide. (In carbon
dioxide one particle of carbon is attached to two particles of
oxygen). Hydrogen and oxygen are mainly absorbed by means of
water. (In water two particles of hydrogen are attached to 1
particle of oxygen). These matters have already been explained.
Nitrogen together with phosphorus and potassium are the main ingredients
in normal fertilisers.
All proteins, also the ones in the plant, contain nitrogen. All
enzymes (these are matters that regulate the character and speed
of the chemical reactions in the plant) are proteins. Especially
chlorophyl with which the plant produces sugars (with the help
of light, water and carbon dioxide) contain many proteins and
therefore a lot of nitrogen. From the previous you might understand
why nitrogen is such an important nutrient for the plant. When
a plant receives too little it is first shown by the colour.
Because so much nitrogen is needed to make chlorophyl, a shortage
will be noticed here first. The plant will become ailingly light
green. This fading starts first with the older leaves.
BUT: when there is
insufficient light it is of no use for the plant to make chlorophyl
which also gives this light green colour. When this is the cause
however, the leaves also tend to "reach out for the light"
in their shape. With a nitrogen shortage you don't see this.
Also with a nitrogen shortage the plant becomes more susceptible
to mycosis. With too much nitrogen the opposite will happen.
The plant becomes unnaturally dark green and the growth stagnates.
Just like nitrogen, phosphorus is important for protein chemistry
of the plant, especially in the regulation processes. A shortage
of it is expressed as slow growth and sometimes a purple-ish colouring
of the whole leaf. The chance of a phosphorus shortage is small
with the right nutrition. An excess is more likely to occur,
especially with substrate cultivation, because phosphorus can
accumulate in the root environment. When this happens the plant
can't absorb enough zinc so the symptoms are similar as with a
lack of zinc. (see Zn).
This nutrient is especially important in the humidity regulation.
With a potassium deficiency, symptoms of burning occur. (see
page 10). With too much potassium there will be a shortage of
calcium and magnesium. (see Ca and Mg). During the flower period
the plant requires more potassium.
Magnesium is necessary for the production of chlorophyl. With
a deficiency the plant will yellow between the veins, initially
in the older (strange enough not in the very oldest) leaves.
Your "favourite plant" is a true magnesium lover. Too
much would make the growth stagnate, but this has never been established
with the cultivation.
This nutrient is "built-in" the cell walls and membranes
of the plant cells. A shortage might occur in the leaves when
the relative humidity is too high (and they cannot evaporate enough
water), and with a potassium overdose. With a lack of calcium,
the young leaves and new buds die. The plant also becomes very
susceptible to mycosis. If the calcium deficiency is being caused
by a too high humidity, the entire crop can be ruined in no time
through moulding. An overdose of calcium has never been established
with this plant.
The plant uses sulphur to build up proteins. Overdoses or deficiency
are unknown in practice.
The plant uses iron in its enzymes. When growing on soil, both
overdose and deficiencies are unknown. When growing on rockwool
however, an iron deficiency might occur as a consequence of a
too high pH.
An iron deficiency is easily recognized by the chlorosis of leaf
tissue on the growing shoots. Leaves in the shoots have a network
of green veins which stand out among the yellow or white tissue
between the veins.
The plant also uses this in its enzymes. Deficiencies and overdoses
are both unknown when growing on soil. A lack might occur when
growing on rockwool because of a too high pH. This is recognized
by a yellowing between the veins of the new leaves (but not the
Copper deficiencies are extremely rare. Be careful not to confuse
this deficiency with the symptoms of overfertilisation.
Zinc is also used in the enzymes. A zinc deficiency is usually
the result of an overdose of phosphorus. The symptoms are chlorosis
of tissue between the veins of top shoots starting at the base
of the leaf. A radial or horizontal twisting of the leaf blades
in the growing shoots is a dead give away.
The plant needs boron to transport sugars. When there is a deficiency
symptoms first appear on the growing shoots which turn brown or
grey and die. The shoots may look burnt. A good indication
of B deficiency is that after the top shoot dies, actively growing
side shoots start to grow but die also.
This nutrient is needed for a few important enzymes in the plant
that play a role in the manufacture of nitrogen. Extremely rare,
look for another cause.
One of the things you never find in other manuals is the following:
We have told you before that the absorption of nutrients is an
active process and that plants can, within certain limits, decide
what and how much they absorb with their roots. Suppose that
a nutrient solution contains nutrient A and nutrient B in equal
amounts. The plant grows fine but it happens to use some more
of A than of B. After some time the EC has dropped and is adjusted
with new nutrients that again contain equal amounts of A and B.
But more has been used of A, so after adjusting, the solution
contains more of B than of A. If this continues for a while the
solution will contain too much of B and too little of A whereas
the EC has the right value. With the EC you determine the concentration
of nutrients but not WHICH nutrients. Besides, the plant also
expels certain toxins through the roots into the drainage water.
For these reasons we strongly advise you not to use the drainage
water a second time.