SGS Growing Guide - Fundamental Hydroponics

HYDROPONIC SYSTEMS

Hydroponic systems
NFT
Rockwool based systems
Continuous drip systems
Ebb and Flow systems
Hydrocorn
Perlite/vermiculite
Aeroponic systems
Summary

Hydroponic gardening is the way of the future for environmentally controlled agriculture. By eliminating soil-borne pests and diseases, while maximizing water and nutrient uptake by the plant, phenominal yields can be achieved in a relatively small space.

HYDROPONIC SYSTEMS

There are many types of hydroponic systems available for commercial and home use.

The Europonic Rockwool System is modelled after commercial systems used in Holland. It uses a rockwool substrate with a continuously recirculating supply of nutrient solution.

Ebb-and-Flow Systems work on a timer. The timer clicks a pump on, flooding the substrate with a nutrient solution. Then the tray is drained, aerating the roots.

Aeroponic Systems provide the greatest aeration to plant roots. The roots are suspended directly in a mist chamber, with highly oxygenated nutrient solution constantly sprayed on the roots.

NFT

NFT, or Nutrient Film Technique, is another popular system. The plants are held in troughs, with nutrient solution constantly trickling over the roots. A reservoir with a submersible pump continually recirculates the nutrient solution, pumping the solution to the top of the troughs to trickle back through the system. Larger NFT systems are used commercially, both domestically and abroad.

When choosing an NFT system, care must be taken to choose the correct trough size. Small 4 inch troughs are fine for most plants, but larger vine crops with extensive root systems could hinder nutrient flow, causing root rot and pathogen growth. Large commercial systems use wider troughs with greater flow capacity.

Lets take a closer look at some other hydroponic systems used in commercial, home and educational settings.

ROCKWOOL BASED SYSTEMS

The Europonic System, using a rockwool substrate, is modelled after commercial systems used in Europe. A basic system has three trays, holding 8 plants each, for a 24 plant capacity, but the system can be expanded to five trays if desired. Nutrient solution is pumped from a 30 gallon reservoir to individual emitters at each plant. The solution trickles through the rockwool, over the roots, then back to the reservoir where it is constantly recirculated.

Rockwool

Rockwool, or mineral wool, is the most popular hydroponic medium. Rockwool is made from spun mineral fibers and has a high air and water holding capacity. It can also be cut and formed into many shapes and sizes, providing many diverse growing applications.

For example, a sheet of 98 rockwool cubes fits perfectly in a standard 11" by 22" nursery tray. After soaking the rockwool in a conditioning solution over night, seeds can be planted directly into the cubes for germination.

After germination, seedlings are transferred to larger blocks until they are ready to be permanently transplanted onto a larger system.

The Europonic System uses rockwool slabs, with two slabs fitting perfectly in each tray. Since rockwool is slightly alkaline in nature, the slabs are treated with a conditioning solution to lower the pH. When the seedlings are ready to be transplanted, X's are cut in the plastic to expose the rockwool slab underneath, and the rockwool blocks containing the seedlings are placed directly on the slab. As the plants develop, their roots will grow horizontally through the slab for the plant's full life. Since rockwool can support a relatively extensive root system, the Europonic System is ideal for vine crops such as tomatoes, cucumbers and peppers, as well as larger flowering plants.

Nutrient Solution

In the Europonic System, nutrient solution is contained in a 30-gallon reservoir, with different nutrient formulas used at various stages of the plant's life. For example, a nitrogen rich "grow formula" is used during a plant's vegetative growth stage, and a phosphorous and potassium rich "bloom formula" is used during the plant's fruiting and flowering stage. The reservoir can be easily emptied and replenished, assuring an ideal nutrient balance during the complete growing cycle.

The amount of solution received at each plant site can also be regulated. A flow valve controls the amount of solution pumped to each tray, and individual emitters for each plant add further control. The emitters have three input positions for low, medium and high flow rates. Most mature plants receive about 1 to 1-1/2 gallons per hour of nutrient solution, but the flow can be regulated to accommodate different sized plants or plants at different stages of maturity.

Therefore, a Europonic system is extremely flexible for both home and commercial applications.

CONTINUOUS DRIP SYSTEMS

For the hobbyist, the Water Garden is an interesting variation of a continuous drip system. A single pot is used with a 2-gallon reservoir underneath. The system acts like a percolator. Air is pumped down a vertical shaft, creating pressure, and nutrient solution is forced up another tube. A drip ring constantly irrigates the substrate, and the nutrient solution drains back into the reservoir.

The Water Garden is inexpensive, easy to use, and great for individual experimentation, but it is impractical for most commercial applications.

EBB-AND-FLOW SYSTEMS

Ebb-and-flow systems are also popular in hydroponics.

For example, in the Hydrofarm version an 44 by 26 inch tray holds the plants and a 25-gallon reservoir with a submersible pump is located underneath. A timer clicks on a pump at regular intervals, and the substrate is flooded to a specified level. After the plant roots are soaked, the timer clicks off, and the nutrient solution drains back into the reservoir, providing good root aeration.

Ebb-and-flow systems are good for crops such as miniature tomatoes, lettuce, pepper plants and potted flowers. It can also be used as an herb garden to provide fresh basil, oregano and thyme year round.

One drawback of ebb-and-flow systems is the possible buildup of fertilizer salts in the substrate. As the water evaporates between floodings, fertilizer salts are left behind as a residue. Over time, the salts may rise to toxic levels. Therefore, it is best to flush the system with pure water periodically to leach away any toxic salt buildup.

Hydrocorn

Hydrocorn is a popular substrate for ebb-and-flow systems. Hydrocorn is made from fired clay. It is light-weight, semi-porous and provides good root aeration. Unlike most substrates, hydrocorn doesn't need to be replaced between crops. Simply soak the substrate in a mild chlorine bleach solution, then rinse thoroughly. Although initially more expensive than many other substrates, hydrocorn is more economical to use in the long run.

Perlite/Vermiculite

A combination of perlite and vermiculite is another popular hydroponic medium. Perlite is hard and brittle, providing excellent drainage and root aeration. Vermiculite is soft and spongy, providing good water and nutrient retention. When used together, an ideal balance is achieved, providing an excellent growing medium from seed through harvest.

AEROPONIC SYSTEMS

Aeroponics is a system in which the plant's roots are suspended in air.

For example, the "Aquamist I" system shown here is a self-contained unit with the plants on top and a mist chamber underneath. Highly oxygenated nutrient solution constantly sprays the plant roots, facilitating phenominal growth.

Aeroponic systems are excellent for growing herbs and leafy vegetables. The plants are held in web pots with neoprene inserts to support the plant, if necessary. Different hole configurations in the top cover provide proper spacing.

Aeroponic systems are also great propagators. Seedlings can be germinated in rockwool, then transferred directly to the web pots, or cuttings can be rooted. If the cutting is dipped in cloning gel, and the leaves sprayed with cloning wax, root development in an aeroponic system will be exceptional.

For educational and research applications, smaller, table-top aeroponic systems are also available. Since each system is self-contained, experiments can be easily done with nutrient solutions, lighting or CO2 levels. Therefore, aeroponic systems are very popular at NASA research centers and other educational facilities around the world.

SUMMARY

Let's take a moment to summarize the pros and cons of various hydroponic systems.

* NFT systems require no hydroponic substrate,

* with the roots only in contact with the nutrient solution.

* NFT is used commercially around the world,

* but the system is mechanically dependent.

* Pump or other mechanical failure could harm a crop in a matter of hours

* and clogging must be avoided to prevent spread of pathogens.

* Rockwool based systems are more mechanically forgiving.

* Rockwool tends to retain water and nutrients

* and helps even out fluctuations in EC and pH levels.

* Rockwool can also sustain extensive root systems,

* making it ideal for vine crops and other long term plants.

* Ebb-and-flow systems have lower start up costs

* and take up relatively little space,

* making them ideal for home and small commercial applications.

* Permanent substrates, such as hydrocorn, may be also be used

* keeping maintenance costs to a minimum,

* but a toxic build-up of salts must be guarded against.

* Aeroponic systems provide the best root aeration of any system,

* resulting in fast root development and vegetative growth.

* Aeroponic systems are also excellent propagating systems

* and are often used commercially for lettuce and herb production.

* Aeroponic systems are also ideal for research and educational facilities,

* providing a self-contained environment for experimentation.

CONCLUSION

Hydroponic systems come in all shapes and sizes, and can be adapted for nearly any budget. So whether you are a commercial grower, hobbyist, or educational researcher, hydroponics is the way of the future for environmentally controlled agriculture.

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