Introduction to Hydroponics 1-2
Four Primary Hydroponic Growing Methods:
In a soil garden, plants are rooted in the soil and draw nutrients from it. In hydroponics, a nutrient rich solution
is fed directly to the plant roots. In some hydroponic growing systems an inert growing medium, such as perlite, rockwool or expanded clay pebbles is used in place of soil. These growing mediums are porous and absorb the nutrient solution, allowing the plants to use it as needed.
In other hydroponic systems, like the NFT system, no growing medium is used and
the plant roots are suspended
in a grow channel.
The four most common methods of hydroponic gardening include:
|Ebb and Flow|
|Nutrient Film Technique (NFT)|
Ebb and Flow
The Ebb and Flow (also know as flood and drain) method of hydroponic gardening simply allows all the plants
in the garden to be fed the same amount of nutrient solution at the same time.
|The plant grow bed, which contains plant
pots filled with a growing medium, is
flooded with the nutrient solution for a set period of time and then allowed to drain
for a set period of time. This allows the growing medium and plant roots to stay
moist while bringing fresh oxygen to the root base each time the nutrient solution
Most Ebb and Flow systems will flood the grow bed for 10 or 15 minutes of every hour or two In an Ebb and Flow system, the plant roots are most commonly grown in a medium of perlite, rockwool or expanded clay pebbles.
An Ebb and Flow system, popular with many home hydroponic gardeners, is ideal for growing a broad variety
of crops since both long and short term crops do well in this system.
In a Drip system, the nutrient solution is delivered to the plants through drip emitters on a timed system. The
timed cycle flushes the growing medium, providing the plants with fresh nutrients, water and oxygen as the
emitter is dripping.
The emitters are usually scheduled to run for approximately 5-10 minutes of every
hour. In a drip system, the plant roots are most commonly grown in a medium of
perlite, grow rocks or rockwool. The drip system is often used in commercial
hydroponic facilities that grow long term crops like tomatoes, cucumbers and
With the Nutrient Film Technique (also known as NFT) the plants are grown in
channels which the nutrient solution is pumped through.
The plant roots are flooded by the nutrient solution as it passes by. Ideally, the bottom of the roots are exposed to the nutrient solution, while the top of the roots are exposed to air. Most NFT systems are fed on a very frequent timed cycle. For instance, 10 minutes of nutrient solution flow, followed by 5 minutes of nutrient solution drain. Since the plant roots are not in a growing medium, it is crucial that they are flushed often to keep them moist.
NFT is ideal for lettuces, leafy crops and herbs, all of which are short term crops. Larger NFT channels can be used long term crops as long as some form of plant support is provided..
The advantage of a Passive hydroponic garden is its low maintenance. A Passive system does not use pumps or timers to flood the root zone. The roots usually dangle in the nutrient solution and draw what they need from it. A Passive system is generally slower growing and not as intensive as the other systems discussed.
Because there is no water movement, passive hydroponic growing systems will often have low oxygen levels. this can be remedied by adding a small air pump that pumps air into the nutrient reservoir.
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