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1. The History of
Hydroponics
Hydroponics
basically means working water ("hydro" means "water" and "ponos" means "labor").
Many different civilizations have utilized hydroponic growing techniques
throughout history. As noted in Hydroponic Food Production (Fifth Edition,
Woodbridge Press, 1997, page 23) by Howard M. Resh: "The hanging gardens of
Babylon, the floating gardens of the Aztecs of Mexico and those of the Chinese
are examples of 'Hydroponic' culture. Egyptian hieroglyphic records dating back
several hundred years B.C. describe the growing of plants in water." Hydroponics
is hardly a new method of growing plants. However, giant strides have been made
over the years in this innovative area of agriculture.
Throughout the
last century, scientists and horticulturists experimented with different methods
of hydroponics. One of the potential applications of hydroponics that drove
research was for growing fresh produce in nonarable areas of the world. It is a
simple fact that some people cannot grow in the soil in their area (if there is
even any soil at all). This application of hydroponics was used during World War
II. Troops stationed on nonarable islands in the Pacific were supplied with
fresh produce grown in locally established hydroponic systems.
Later in
the century, hydroponics was integrated into the space program. As NASA
considered the practicalities of locating a society on another planet or the
Earth's moon, hydroponics easily fit into their sustainability plans. This
research is ongoing. But by the 1970s, it wasn't just scientists and analysts
who were involved in hydroponics. Traditional farmers and eager hobbyists began
to be attracted to the virtues of hydroponic growing. A few of the positive
aspects of hydroponics include:
• The ability to produce higher yields than
traditional, soil-based agriculture.
• Allowing food to be grown and consumed
in areas of the world that cannot support crops in the soil.
• Eliminating
the need for massive pesticide use (considering most pests live in the soil),
effectively making our air, water, soil, and food cleaner.
Commercial
growers are flocking to hydroponics like never before. The ideals surrounding
these growing techniques touch on subjects that most people care about, such as
helping end world hunger and making the world cleaner. In addition to the
extensive research that is going on, everyday people from all over the world
have been building (or purchasing) their own systems to grow great-tasting,
fresh food for their family and friends. Educators are realizing the amazing
applications that hydroponics can have in the classroom. And ambitious
individuals are striving to make their dreams come true by making their living
in their backyard greenhouse, selling their produce to local markets and
restaurants.
And now that so many people from so many different walks of
life are involved in hydroponics and its associated disciplines (such as
aeroponics and aquaponics), progress is coming faster than ever
before.
2. What is
Hydroponics?
While the true
definition varies from expert to expert, hydroponics is basically the growing of
plants without soil. The word “Hydroponic” is derived from the Greek words –
“Hydro” which means water and “Ponos” which means labor. True hydroponics is
growing plants in water without any type of media e.g. NFT and Aeroponic,
however, growing plants in soilless media such as coco, perlite rockwool etc are
also classified as hydroponics.
3. What is pH, and how can I test for it?
pH stands for “Potential of Hydrogen” and is the
symbol for the hydrogen ion (H+) in liquids. pH has a range from 0 (acidic) -14
(alkaline), with 7 being neutral. For hydroponics we are aiming for a pH between
5.5 to 6.2 (slightly acidic); this is suitable for most hydroponic crops. For
soil, we want the pH a little higher but still slightly acidic; around 6.0 to
6.5. Ensuring that the pH remains within this range will help maintain good
plant health. Keeping the pH in this range ensures that nutrients are readily
available to the plant. Once the grower goes above or below this optimal range
certain nutrients start becoming unavailable to the plant (e.g. iron
deficiencies will appear at a pH of 6.5 and above).
All hydroponic
growers need to test the pH of their nutrient solution for successful growing.
The pH of a solution can be tested using a standard pH test kit (sample vial
with drops of indicator solution), litmus test strips, or a digital pH meter.
Litmus paper and standard test kits are cheap and easy to use; however, the
degree of accuracy isn't very high. Digital pH meters, although more expensive
than the alternatives, are easy to use and very accurate.
4. Should I top-off my reservoir with plain water or nutrient solution?
In the summer or
in hot grow rooms, plants, in general, will take up more water than nutrients,
thus causing the nutrient solution to become more salty. In the winter time or
in cooler grow rooms, the opposite will occur. Nutrient uptake will also be
determined by the type of crop being grown e.g., tomatoes are heavier feeders
than lettuce. It is extremely important that the grower has both a TDS meter and
a pH meter and that regular testing on the nutrient solution is carried out. If
the grower notices after a few days that the ppm level in the reservoir is high
and the water level has decreased than the grower should top up their reservoir
with either plain water or a weak nutrient solution until the optimum ppm level
is reached. If the grower has noticed a drop in ppm levels then a full strength
nutrient solution should be used to top off the reservoir. Another factor to
consider is the source water. You will generally find that if you are not using
reverse osmosis water, you will usually have to top-off with plain water, since
tap water has a lot of sodium and minerals that increase the ppm levels. Here is
an ideal scenario: Purchase a Reverse Osmosis System, Auto Shut-off Kit and some
R.O. Tubing, which can be found in the Water Treatment section of our website,
and a ¼” Grommet and a ¼” Float Valve, which can be found in the Plumbing
section. Also purchase a Rubbermaid trash can and a couple of cinder blocks from
your local hardware store. Hook up the R.O. system and shut-off kit according to
the instruction manuals. The float valve that comes with the shut-off kit should
be installed in the trash can, which should be placed on the cinder blocks for
elevation. Drill a hole close to the bottom of the trash can and insert the
grommet. Install the second float valve in your reservoir, a little higher than
where you want the water level to be. Then, run a length of R.O. tubing from the
grommet to the float valve. Now, turn on your R.O. system and go spend the time
you’re going to save doing something fun! After a period of time, both the
reservoir and the trash can will be full, and the R.O. system will stop. It will
only come on when the levels in either receptacle begin to fall. Once you add
nutrients and enhancers to the reservoir, you will find that the PPM level
actually drops each day as the plants take up nutrients and the water is
replenished through the float valve (this is especially visible with healthy,
actively growing plants). You will also find that you use far less pH adjusting
solutions due to the improved water quality. You should only have to add small
amounts of nutrients and pH adjusting solution every once and a while between
reservoir changes. And, you will always have plenty of pure, fresh water
available in the trash can.
5. What kind of
maintenance is involved with a hydroponic system?
As with soil-based production, producing crops
in hydroponic systems always requires maintenance. The following list may seem
like a lot of work; however, as you become experienced most tasks and checks
will only take a few minutes each day.
Daily
* Check
reservoir for water levels, pH and TDS fluctuations.
* Check grow room
temperatures and humidity percentages.
* If you use CO2, the CO2 system
should be checked to ensure that it is working correctly.
* Check
watering system. If a pump fails it should be replaced immediately. If drippers
are blocked they should be cleaned or replaced immediately.
* Check
plants for disease and insect infestations. It is always best to stop disease
and insect outbreaks early. The longer an infestation is left the more difficult
it will be to cure, yield losses will be high and crop failures are
possible.
* Check plants for leaf discoloration and deformities that may
be caused by such problems as nutrient deficiencies or nutrient burn (over
feeding), as well as leaf curl from lights being to close.
* Crop hygiene
is extremely important. Cut off and discard diseased leaves. If a plant is badly
diseased, it is always better to throw out one or two plants to control disease
outbreaks than it is to destroy a complete crop. The same applies to insect
infestations, especially spider mites.
* General maintenance - failed
light bulbs, light movers, fans, loose ducting, leaks etc. should be replaced or
repaired.
Weekly
* The growing medium should be flushed
once a week to stop nutrient lock up.
* Complete reservoir change should
done weekly to prevent nutrient imbalances and bacteria build-up.
*
Foliar spraying for disease and insect pests should be done weekly to prevent
outbreaks.
End of each crop
* The hydroponics system should be
completely sanitized at the end of each crop. This will minimize disease carry
over to the next crop.
* The grow room should be sanitized with
insecticides and fungicides. Walls, floors, ceilings and equipment should be
wiped down to remove insects/eggs and fungi spores. The cleaner the grower is in
his growing room the fewer problems he will have in the following
crop.
6. Total Environmental Control
Too hot
in your room – vent out your light. Too cold - add a heater. Too humid - bring
in some fresh air. Indoor gardening allows you to provide optimal conditions for
your plants to grow in. Being indoors also helps avoid mold, pests and other
adverse creatures.
7. How often should you change your reservoir?
We recommend that you change your reservoir once a week.
This entails “dumping” your reservoir and re-filling it with fresh water and
nutrients. The reason for this is that as the plants feed, the nutrient solution
will fall out of balance. Also, bacteria grows at a geometric rate. If you
change your solution every week you will decrease the possibility of bacteria
becoming a problem. While it is possible to go longer between changes if you are
using reverse osmosis water instead of tap water, you still have the bacteria
issue to contend with, so unless you are using something to inhibit the
bacterial growth, you should still change your reservoir weekly.
8. What size water pump do I need for a reservoir that hold “x”
number of gallons?
The size of your pump doesn’t depend on the size
of your reservoir; rather it depends on how far you need to pump your water and
how much water you need to pump. You want to avoid overworking your pump, so in
choosing the proper pump you will want to choose one with at least 20% more
power than need. To find out your appropriate pump size you will need to
determine how much water is necessary to fill your tray. If your tray is in the
shape of a rectangle or square then you will need to apply the following formula
to determine its volume:
Length (ft) x Width (ft) x Average Depth (ft) x
7.5 = ? US gallons
This will give you the total gallons that your tray
can hold. It is a good idea to always get a pump that is at least 20% larger
than necessary to avoid overworking it.
After you’ve determined your
volume requirements you need to find out how far “up” the water needs to be
lifted in order to reach the tray. Simply measure the distance between your pump
and the entry point in your tray; most systems will have a distance of under 3’.
This vertical distance will have an adverse affect on the pump and this affect
must be accounted for. In essence, the greater the vertical distance the water
must travel, the stronger the pump needs to be. The following chart will show
you how vertical distance affects the pumps. Note the loss of power of each pump
as the vertical height increases.
9. What does an air
stone do?
An air stone helps to provide oxygenate the nutrient
solution. This oxygen is extremely beneficial to the root zone and helps to
promote fast, healthy growth as well as prevent disease. This is one of the main
reasons that plants growing in a hydroponic system grow so much faster than
plants in soil. If you are growing in soil you can still reap some of the
rewards of oxygen by simply oxygenating your water before applying it to the
soil.
10. What is the
difference between HPS and MH and fluorescent lights?
What kind of lighting do I need to grow
plants?
There are two primary types of lighting used to grow plants. High
Intensity Discharge (HID) is by far the most common, and includes Metal Halide
(MH), which is used primarily for the vegetative stage of growth, and High
Pressure Sodium (HPS), which is used during the flowering or fruiting stage. You
can find more information on HID lighting further down in this FAQ
section.
Another popular type of plant lighting is Fluorescent lighting.
Fluorescent lighting is used primarily for starting seedlings and cuttings, but
T-5 fluorescent bulbs are strong enough to grow short plants from start to
finish. It is important to note that not all fluorescent lighting is the same
and only certain types should be used for growing plants. Most (if not all)
standard fluorescent tubes are fine for illuminating a garage or office, but
usually lack the spectrum and intensity needed to sustain plant growth. It
should also be noted that if you are growing houseplants that require very
little light to sustain growth, you can probably get away with some of the
inferior types of fluorescent lights. But, if you are growing plants that need
plenty of natural sunlight in order to thrive (such as vegetables and flowers),
you will be extremely unhappy with the results you get from these bulbs.
There are three types of fluorescent bulbs that are considered suitable
for plant growth: Standard tubes with enhanced spectrum (such as the Verilux),
Compact fluorescents and T-5 fluorescents.
Verilux
Verilux bulbs look similar to the bulbs you
typically find in shop lights and offices. The main difference is that, unlike
standard tubes which lose their intensity and spectrum in as little as 6 weeks,
Verilux tubes retain their properties much, much longer. They also have a
spectrum that is extremely close to natural sunlight. They can be used in any
standard shop light fixture. They should only be used for growing houseplants,
orchids, or for starting seedlings or cuttings.
Compact Fluorescents
These bulbs are
available in a variety of wattages ranging from 95W up to 200W. They produce a
higher lumen output than regular fluorescents, and are available in 6500K
(daylight) for vegetative growth and 3000K (red) to enhance flowering. Unlike
regular fluorescents, compact fluorescents do not require a fixture, since the
ballast is built in to the base of the bulb. They require a socket (the same
type of socket you would use for an HID bulb) and a power cord, and can be used
with or without a reflector. Using a reflector, however, will direct more of the
light down onto the plants. Another common use for compact fluorescents is to
hang them vertically, usually without a reflector, in between large plants to
provide supplemental side lighting. Compact Fluorescents can be used for growing
houseplants, orchids, or for starting seedlings or cuttings. For plants that do
not require full sunlight, or for varieties that tend not to stretch under
weaker light, these bulbs can be used for the entire vegetative stage, and in
some cases flowering as well.
T-5
Systems
T-5’s are the best fluorescent light bulbs available. They
are similar to standard fluorescent tubes, only much smaller in diameter. They
put out far more light then standard fluorescents, and have a much better
spectrum as well. T-5’s must be used in a T-5 fixture; they will not work with
standard fixtures. They are available in different sizes and configurations,
ranging from 2’ two bulb fixtures up to 4’ eight bulb fixtures. The eight bulb
fixture is approximately equivalent to a 600W HPS lighting system. T-5 bulbs are
available in 6500K (daylight) for vegetative growth and 3000K (red) to enhance
flowering. T-5 systems are excellent for starting seedlings and cuttings, and in
many cases take plants from start to finish, provided you keep the plants on the
short side.
The rest of this lighting FAQ pertains mainly to HID lighting
systems.
11. What size (wattage) lighting system do I
need?
There are two things to consider when deciding what size lighting
system to use: the actual area in which the plants will be taking up, and how
tall you want your plants to grow. 150-175 watt lights are primarily used for
seedlings or cuttings, though they can be used for growing plants to maturity if
the plants are kept short. 250 watt systems are good for areas up to 2.5' square
at the most, as long as the plants don't get taller than about 2'. 400 watt
systems cover a primary area of about 3' x 3', or up to 4' x 4' max. 600 watt
systems cover a primary area of about 4' x 4', or up to 5' x 5' max. 1000 watt
systems cover from 4' x 6' up to 5' x 7'. The taller you plan to grow your
plants, the higher the wattage needed. This is because the light intensity
diminishes by 50% for every foot you move away from the bulb. So, if your plants
reach 4' tall, then the leaves at the bottom of the plant are receiving only
around 12% of the light that the top of the plant is getting!
BALLASTS:
Magnetic ballast have been the standard for
decades.
The Digital Ballast represents a breakthrough in HID lighting,
and offer many benefits:
· Works with both MH and HPS bulbs
·
Energy savings of up to 30%*
· Produces no heat
· No start-up
spike of electricity
· Power factor (efficiency rating) is 99%
·
Consistent wattage output - improves bulb life
· Components are
American-made
· No stroboscopic (flickering) effect - as close to
natural sunlight as you can get
· These ballasts also have a built-in
safety feature. If an open circuit exists while trying to ignite the lamp, the
ballast will stop and then attempt to ignite the lamp again every 30 seconds for
2 minutes. The ballast will then go into a sleep mode for 30 minutes and then
repeat. This saves many dangerous and unnecessary attempts to ignite and burn
out the ballast, which could result in safety hazards.
REFLECTORS:
The reflector is undoubtedly the
single most important factor to consider when choosing a lighting system. The
reflector dictates whether the light is concentrated on the plants, or splashed
up against the walls. While some bulbs are a little brighter than others, a
quality reflector can reflect up to 50% more light straight down onto the plants
than a lower quality reflector. Here’s a common mistake that first-time growers
make. They see a reflector that is advertised as covering up to an 8’ x 8’ area
(with a 1000W bulb installed). Then they see another reflector advertised as
covering only a 4’ x 6’ area, and for more money, too! Which would you choose?
Well, consider this: Let’s say that a 1000W HPS bulb puts out 140,000 lumens
(lumens is a measure of light intensity). Now, let’s say that you have a jar
containing 140,000 marbles, each marble representing one lumen. You pour this
jar into an area that measures 8’ x 8’. You get a pretty thin layer of marbles.
Now, pour this same jar into a 4’ x 6’ area, and you have a much thicker layer
of marbles, right? Is it starting to make sense? Stay away from the reflectors
that throw the light all over the place, unless you are growing houseplants! The
smaller the area covered, the brighter it will be, and the better your plants
will grow and yield. Horizontal hoods are the best choice for plants that
require a lot of light, such as most vegetables & flowers. Horizontal hoods
direct the light straight down on the plants, throwing more intense light over a
smaller area. This is by far the most popular choice among growers. Air-cooled
hoods have flanges that allow you to hook an exhaust fan to the hood to suck out
the hot air generated by the bulb, thus reducing the amount of heat in the grow
room.
Urban Gardener offers the largest selection of reflectors anywhere,
by leading manufacturers such as P.L. Light Systems, Sunlight Supply, Hydrofarm,
and, last but not least, Urban Gardener.
You can find detailed
information on all of the reflectors we currently carry in the Reflectors
category on our website.
BULBS:
How often
do I need to replace my bulbs?
Urban Gardener recommends that HPS bulbs
should be replaced at least every 12 months (8 months or less is ideal). MH
bulbs should be replaced every 9 months (6 months or less is ideal) for maximum
efficiency. The use of a light meter would be the best and most accurate way in
which to measure your bulbs output as well as to help with bulb replacement
timing.
What is the difference between an MH Regular and Super Bulb and
how do I know which one I need to buy?
A Metal Halide Super Bulb has a
higher lumen (light) output, and is almost always position oriented. These bulbs
have a pin sticking out of the side of the mogul (base) where the bulb screws
into the socket. These bulbs require a position oriented socked that is designed
to catch the pin so that the bulb is rotated into the correct position,
otherwise the bulb will not perform as expected. In addition, these Super MH
bulbs must be burned in a horizontal position only. All other bulbs
(non-position oriented), including the MH Regular bulb, can be burned in either
a horizontal or vertical position (i.e. they are universal) unless otherwise
noted in the individual bulb description.
GENERAL:
What is a recommend lighting schedule for
Vegetation and Flowering?
For Clones/Seedlings and Vegetative Growth
Urban Gardener recommends using an 18 hours on/6 hours off lighting schedule. In
order to induce your plants to flower we recommend subjecting your plants to a
12 hours on/12 hours off lighting schedule.
12. Is it
OK to leave my lights on 24 hours per day?
Urban Gardener does not
recommend running lights 24 hours under any circumstances. Your plants need a
time to “rest” and grow. This is achieved during the dark period. Running your
lights for 24 hour cycles may have a detrimental affect on your lighting system
and your plants, not allowing them to develop properly. In addition, many plant
species do most of their feeding during the night, especially when daytime
temperatures are high or humidity levels are low.
13.
How do I determine how much my electric bill will increase by using a lighting
system?
First, find out what your
electricity provider is charging you per kilowatt hour (KWH). In Los Angeles,
it’s approximately $0.10/KWH, but this number will vary from city to city. This
number represents what a 1000W lighting system will cost you per hour to run.
So, if you have a 400W system, the number to use in the following steps would be
0.4, for a 600W system it would be .06, and so on. Next, multiply this number by
the number of hours per day you plan to operate your lighting system. This will
give you the cost per day. Finally, multiply this number by 30 to see
approximately what it will cost per month.
Refer to the following
example:
0.10 (KWH cost for a 1000W lighting system) x 12 (hours per day) x
30 (days per month) = $36.00 per month
Nutrients
14. How do I choose which
nutrient to use?
There are many brands of nutrients that are
available to hydroponic growers. The grower should first decide if they want to
grow organically or conventionally. The type of growing medium will also
determine what type of nutrient a grower should use, e.g. if coco growing medium
is used then you should consider using nutrients that are designed for coco
(like Canna Coco nutrients). The crop stage will also determine what nutrient
should be used e.g. a vegetative nutrient formula should be used when a plant is
in vegetative stage (such as Super Veg A and Super Veg B). Ultimately, the brand
of nutrient which the hydroponic grower should use is purely up to the grower to
decide. And, as always, feel free to contact our sales staff and we will be
happy to make recommendations based on our own experience and the feedback we
get from our successful customers.
15. What is NPK, how does it affect my plants, and what combinations do I
need?
N – Nitrogen
Nitrogen is a unique
element, as plants are able to take up nitrogen in the form of an anion (a
negatively charged molecule) or a cation (a positively charged molecule). Plants
are able to take up nitrogen in as NO3 or Nitrates and NH4 Ammonium. Plants
require or consume more nitrates than ammonia, thus its not. A well balanced
nutrient solution will have less than 10% of available nitrogen in the form of
ammonia. Nitrogen has many functions in the plant; it is found in proteins,
chlorophyll, protoplasm and plant hormones.
Source – All premixed
nutrients will have adequate nitrogen levels. If a customer wishes to give his
plants extra nitrogen in the vegetative stage then he can use Cal-Mag Plus at a
rate of 1-2 teaspoons (5-10ml) per gallon. This will supply the plant with 25 –
50ppm extra nitrogen, this will be more than adequate. Using Cal-Mag will also
supply the plant with extra Calcium, Magnesium and Iron. If a customer wishes to
use an organic source of nitrogen then they can use Mexican Bat Guano. Note that
only 1% of the 10% of nitrogen in Mexican Bat Guano is readily available to the
plant, the other 9% will slowly be released over a few weeks as the organic
nitrogen is broken down. Bat Guano cannot be used in NFT or aeroponic systems;
it will also have a limited affect in ebb and flow and drip systems. Bat Guano
is ideal for soil growers.
Deficiency – Growth is slow, sparse and
spindly the older leaves turn yellow and will eventually dry out and die. The
complete leaf will turn yellow, with no green veins.
Toxicity – The
plants will produce excess foliage that will be dark green. The plants will also
be softer, disease and insect outbreaks will be severe (this will be due to a
weaker softer plant). The root system will also be underdeveloped. High nitrogen
levels can also retard flowering and fruiting, decrease in yields as flowers
don’t set and lower fruit quality. Nitrogen deficiency and toxicity is rear and
will not be a problem if growers use premixed nutrients and follow the
directions for these nutrients.
P – Phosphorus
Phosphorus is a very important nutrient
for plants. It is required by seedlings, newly rooted clones and flowering and
fruiting plants. Phosphorus is essential for the development of healthy roots,
stimulation of flowering, ripening of fruits and seed production. Phosphorus is
also required for the hydrolysis of starch to sugar and for the synthesis of
starch to sugars (also known as energy transfer).
Source – Again, premix
nutrients will have adequate phosphorus for general plant growth. Plants will
need extra phosphorus when the plants begin flowering and fruiting. This is why
growers must change from a vegetative formula to a flowering formula. The
flowering formulas will have higher phosphate and potassium levels to help
stimulate flowering, fruiting and seed production. This all culminates in higher
yields and better tasting produce. Taste is increased because of higher
synthesis of starch in to plant sugars. For a customer to really boost their
yields of flowering and fruiting crops it is advisable for them to use a
blooming enhancer. Bloom Booster, Monster Bloom, KoolBloom and PK13/14 are all
products that will boost phosphorus and potassium levels. Bloom Blaster and
Monster Bloom must be applied at a rate of 1 teaspoon (5 grams) per 5 galloons
of water. Kool Bloom ¼ teaspoon per gallon or 1¼ teaspoons per 5 gallons of
water. PK13/14 must be applied at a rate of 1¼ teaspoons (5ml) per gallon of
water. For organic growers, in the soil, Jamaican Bat Guano can be used at a
rate of 2-3 (10-15 grams) tablespoons per gallon of water.
Deficiency –
Plants are stunted and the leaves turn dark green to purplish color. This is due
to a buildup of Anthocyanin pigments. These symptoms occur in the older leaves
first. Plant maturity will also be delayed and yields will be low. Seed
production is also severely affected.
Toxicity – Phosphorus toxicity is
very difficult to diagnose. Excess phosphorus will cause deficiencies of
calcium, iron, copper and zinc. This will cause confusing signals as other
minerals may be showing signs of deficiencies even when adequate amounts of
these minerals are present.
K – Potassium
Potassium is the catalyst in plants. It is
important for the manufacture and transport of plant sugars/carbohydrates,
increases the chlorophyll in leaves, regulates the opening and closing of the
leaf stomata and aids in disease resistance, water uptake and ripening process
of fruits. Potassium is also found in the juice of fruits which contributes to
an increase of fruit taste and fruit quality.
Sources – The sources of
potassium are the same for Phosphorus above.
Deficiency – Symptoms occur
in older leaves first with yellow blotches and in severe cases dead spots will
occur. Branches and stems will weaken and eventually becomes brittle. Flowering
and fruiting is diminished and yields are low and poor in
quality.
Toxicity – leaf margins may burn in sever cases, but often it
will effect the uptake of magnesium and magnesium deficiencies will
occur.
Ca – Calcium
Calcium is as important as N, P and K. Calcium
is required in the roots, stems, leaves and fruits of plants. It is found in
every cell wall and is required for the absorption of nitrogen.
Sources –
Most nutrient solutions will have adequate calcium for general plant growth. If
a customer is using RO water then they should consider using Cal-Mag Plus. An
application rate of 1-2 (5-10ml) teaspoons per gallon of water is sufficient to
rectify any deficiencies.
Deficiency – Flower bud development is
retarded, thus reducing yields, fruit size is decreased. Roots die, leaving the
plant open to root rot attack. Young leaves show symptoms before older leaves.
The leaves can be deformed, and have yellow blotches which later turns into dead
spots.
Toxicity – No visual symptoms; may cause magnesium
deficiency.
Mg – Magnesium
Magnesium is
found in the chlorophyll molecule. If a deficiency of magnesium occurs then
magnesium is transported from the lower leaves to the new leaves. Magnesium
uptake is affected by the concentration of Potassium. If high levels of
potassium are applied then the amount of magnesium should increase e.g. at the
second week of flowering when blooming enhancers are used then Cal-Mag Plus
should be applied.
Sources – Most nutrient solutions will have adequate
amounts of magnesium. If a grower is using RO water then Cal-Mag Plus should be
used.
Deficiency – Older leaves, lower half of the plants’ leaves show
signs of yellowing. The yellowing occurs between the leaf veins which remains
green.
Toxicity – There are visual symptoms for magnesium
toxicity.
Si – Silicon
Accumulates mostly in
the epidermal cells of a plant. It is also found in other cell walls. Silicon
helps creates hardier, heavier and stronger plants. It has also been known to
increase the plants resistance to fungal attacks.
Sources – Silica Blast
and Pro-Tekt (both potassium silicate) and Pyrosol are the main sources of
silicon. Growers should take care when using these products as they will
increase the pH of the nutrient solution, thus the grower will need to add pH
Down to bring the pH back to 6.
Deficiency – Deficiencies of silicon have
been known to reduce yields.
Toxicity – Not known.
Why are some
nutrients split into an “A” and “B” formulas?
Nutrients are split into
two formulations because the phosphorus, calcium and sulfur nutrients need to be
separated from each other. If this is not done, then the calcium and phosphorus,
as well as the calcium and sulfur, in high concentrations, will react with each
other to form calcium phosphate (cement) and calcium sulfate (gypsum). Both
calcium phosphate and calcium sulfate precipitate out of solution, forming a
white precipitate (which will usually fall to the bottom of the reservoir), and
are unavailable to the plants. This will cause phosphorus, calcium and sulfur
deficiencies in the plant. Once these nutrients are mixed together in the
reservoir they are at lower concentrations and also a pH balanced nutrient mix
will prevent the three nutrients from reacting with each other. This is another
reason why balancing pH is extremely important.
Some nutrients are one
part such as FloraNova Grow and Bloom, are extremely thick and need to be shaken
well before mixing into the reservoir. If these nutrients aren’t shaken well
before use then the precipitates that have formed at the bottom of the bottle
aren’t remixed into solution. This will cause deficiencies, slow growth and
reduced yields.
Some nutrients also come in three parts. This is done
with some brands of hobby hydroponic nutrient formulas so that the grower can
mix the three parts in different ratios to create different solutions for the
vegetative and bloom stages, as well as for different types of plants, without
having to switch to a different product. Most commercial formulas, however, are
two part (you’ll never see a commercial hydroponic farm using a one or three
part nutrient formula; they are primarily for hobby growers).
Urban
Gardener is always available to help you make the decision.
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