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Beginner's Growing Tips
This packet has been designed to help answer the important questions beginning growers
might have when just getting started in hydroponics. A lot of these concepts are
connected to each other.
Carbon Dioxide
During photosynthesis, plants use carbon dioxide (CO2), light, and hydrogen (usually
water) to produce carbohydrates, which is a source of food. Oxygen is given off in this
process as a by-product. Light is a key variable in photosynthesis.
Growing Medium
Soil is never used in hydroponic growing. Some systems have the ability to support the
growing plants, allowing the bare roots to have maximum exposure to the nutrient
solution. In other systems, the roots are supported by a growing medium. Some types of
media also aid in moisture and nutrient retention. Different media are better suited to
specific plants and systems. It is best to research all of your options and to get some
recommendations for systems and media before making investing in or building an
operation. Popular growing media include:
 Composted bark. It is usually organic and can be used for seed germination.
 Expanded clay. Pellets are baked in a very hot oven, which causes them to expand,
creating a porous end product.
 Gravel. Any type can be used. However, gravel can add minerals to nutrient.
Always make sure it is clean.
 Oasis. This artificial, foam-based material is commonly known from its use as an
arrangement base in the floral industry.
 Peat moss. This medium is carbonized and compressed vegetable matter that has
been partially decomposed.
 Perlite. Volcanic glass is mined from lava flows and heated in furnaces to a high
temperature, causing the small amount of moisture inside to expand. This
converts the hard glass into small, sponge-like kernels.
 Pumice. This is a glassy material that is formed by volcanic activity. Pumice is
lightweight due to its large number of cavities produced by the expulsion of water
vapor at a high temperature as lava surfaces.
 Rockwool. This is created by melting rock at a high temperature and then
spinning it into fibers.
 Sand. This medium varies in composition and is usually used in conjunction with
another medium.
 Vermiculite. Similar to perlite except that it has a relatively high cation exchange
capacity--meaning it can hold nutrients for later use.
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Macronutrients
Plants need around 16 mineral nutrients for optimal growth. However, not all these
nutrients are equally important for the plant. Whichever type of hydroponic system you
select or create, you must supply the plants with nutrients. In soil, these elements come
from rock and mineral leaching and organic matter decomposition. They are "held" by
the soil particles and dissolved in the surrounding
water. In hydroponics, the liquid solution is taken in
directly by the roots and provides the leaves with
nutrients through the transportation system in the
stem. These nutrients or minerals are not actual food,
but elements vital to helping the plant utilize the
sugars (the real food) that it produces during
photosynthesis.
Three major minerals--nitrogen (N),
phosphorus (P), and potassium (K)--are used
by plants in large amounts. These three
minerals are usually displayed as hyphenated
numbers, like "15-30-15," on commercial
fertilizers.
These numbers correspond to the relative
percentage by weight of each of the major nutrients--known as macronutrients--N,
P, and K. Macronutrients are present in large concentrations in plants. All
nutrients combine in numerous ways to help produce healthy plants. Usually,
sulfur (S), calcium (Ca), and magnesium (Mg) are also considered macronutrients.
These nutrients play many different roles in plants. Here are some of their
dominant functions:
Primary Nutrients:
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Nitrogen (N)--promotes development of new leaves
Phosphorus (P)--aids in root growth and blooming
Potassium (K)--important for disease resistance and
aids growth in extreme temperatures
Secondary Nutrients:
 Sulfur (S)--contributes to healthy, dark green color in leaves
 Calcium (Ca)--promotes new root and shoot growth
 Magnesium (Mg)--chlorophyll, the pigment that gives plants their green
color and absorbs sunlight to make food, contains a Mg ion
Nutrient Solution
In hydroponics, nutrient solution--sometimes just referred to as "nutrient"--is used
to feed plants instead of plain water. This is due to the fact that the plants aren't
grown in soil. Traditionally, plants acquire most of their nutrition from the soil.
When growing hydroponically, you need to add all of the nutrients a plant needs
to water. Distilled water works best for making nutrient.
Hydroponic gardeners provide plant roots with a nutrient solution containing an
appropriate balance of necessary nutrients -- a "super nutrient soup.” The easiest
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way to supply them is to purchase prepared hydroponic nutrients in dried or liquid
form. Most are concentrated and must be mixed with water.
Mixing Solutions
When mixing nutrient solutions, always dilute them to the concentration
recommended by the manufacturer, typically 1 or 2 teaspoons per gallon of water.
Water between 65 and 75 degrees F makes nutrients most available to plants. Tap
water may contain significant concentrations of chlorine, which can adversely
affect plant growth. If your water has a lot of chlorine, you can use distilled water
or simply let water stand uncovered for a couple of days before using it.
How Much to Use Nutrient Solutions
The amount of nutrient solution you use depends on the type of system,
temperature, light, and other factors. If you're growing plants like lettuce, herbs,
or flowers in a simple system such as a floating raft, a good rule of thumb is to
provide 2 quarts of nutrient solution per plant. If you're trying to raise larger,
fruiting crops in a more sophisticated system, you'll need to supply closer to 2
gallons of nutrient solution per plant.
Maintaining Nutrients
You'll have to replace the nutrient solution at different intervals depending on the
type of system you set up, because nutrient concentration will vary as nutrients
are taken up by the plant and as water evaporates and transpires from plant leaves.
(Commercial growers use special equipment to measure the concentration of
nutrients in a solution.) A good general rule for most systems is to replace the
mixture with a fresh batch every 10 to 21 days.
Osmosis
With plants, this action allows water and nutrients to pass through the root walls
from the top, sides, and bottom. Osmosis is the natural energy force that moves
elemental ions through what appears to be solid material. A simplistic explanation
for how osmosis works, although not 100 percent accurate, is that the stronger ion
attracts the weaker through a semipermeable material. So, the elements within the
cells that make up plant roots attract water and nutrients through the root walls
when these compounds are stronger than the water and nutrients applied to the
outside of the roots.
It then follows that if you apply a strong nutrient to the plant roots--one that’s
stronger than the compounds inside of the root--that the reverse action is likely to
occur! This process is called reverse osmosis. Many gardeners have at some time
committed the sin of killing their plants by applying too strong a fertilizer to their
plants, which causes reverse osmosis. Instead of feeding the plant, they have
actually been dragging the life force out of it.
pH
The pH of a nutrient solution is a measurement of its relative concentration of
positive hydrogen ions. Negative hydroxyl ions are produced by the way systems
filter and mix air into the nutrient solution feeding plants. Plants feed by an
exchange of ions. As ions are removed from the nutrient solution, pH rises.
Therefore, the more ions that are taken up by the plants, the greater the growth. A
solution with a pH value of 7.0 contains relatively equal concentrations of
hydrogen ions and hydroxyl ions. When the pH is below 7.0, there are more
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hydrogen ions than hydroxyl ion. Such a solution "acidic." When the pH is above
7.0, there are fewer hydrogen ions than hydroxyl ions. This means that the
solution is "alkaline."
It is also a good idea to test the pH level of your water before adding any nutrients.
If your solution is too alkaline add some acid. Although such conditions rarely
occur, sometimes you may have to reduce the level of acidity by making the
solution more alkaline. This can be achieved by adding potassium hydroxide (or
potash) to the solution in small amounts until it is balanced once again.
Photosynthesis
Plants need to absorb many necessary nutrients from the nutrient solution or--in
the case of traditional agriculture--the soil. However, plants can create some of
their own food. Plants use the process of photosynthesis to create food for energy.
Carbohydrates are produced from carbon dioxide (CO2) and a source of hydrogen
(H)--such as water--in chlorophyll-containing plant cells when they are exposed
to light. This process results in the production of oxygen (O).
Water
Because the water supply is the source of life for your plants, quality is important.
All plants rely on their ability to uptake water freely. Between 80 and 98 percent
of this uptake is required for transpiration (loosely compared to perspiration in
animals), which allows the plant to produce and somewhat control its immediate
microclimate. Plants also need clean, uncontaminated water to produce their own
healthy food supply.
The water you use in your hydroponic system needs to be pure. It is always a
good idea to test your water source before adding nutrients so you aren't adding
an element that is already present.