Hydroponics

Hydroponics is a method of growing plants with a nutrient rich solution instead of soil. Typically done indoors in order to control the growing process.

Pros:

  • No soil needed
  • Most diseases and weeds eliminated
  • No interference from outdoor pests, meaning fewer pesticides
  • Less water required
  • Plants can be grown year round
  • Grown faster with larger yields

Cons:

  • Requires a little extra knowledge and training
  • More frequent maintenance
  • Fully dependent on watering system
  • Higher set up costs
  • Growing medium still required

Techniques

Aeroponics
Technique of suspending the plants roots and periodically spraying or misting the roots with a nutrient rich solution.

How it works:
The plants are housed in opaque pipes and holes are drilled where the roots are suspended and a mister is placed next to the plant roots to be fed.
Advantages and Disadvantages:
This technique allows for more oxygen to the root allowing the cultivated plants to grow at a fast rate. The plants usually grow twice as fast. The system is somewhat expensive and usually used for high value crops.

Drip Systems
Most common and popular of the techniques. A pump is submerged in a nutrient rich solution and is hooked to a timer. When the timer is activated the solution is then sprayed onto the root base of the plants.

Advantages and Disadvantages:
Most systems have recovery systems which collect the excess solution to be reused again saving money and water. In the event that the feeding tubes get clogged and the plants may dry out. To prevent salt clog up which is the main source of the clogs it is recommended you flush regularly with distilled water. Another issue is that drip systems carry a high setup cost. Pumps and tubes must be purchased and, because of their constant use, may only last a few harvests before they wear out and must be replaced.

Ebb and Flow
In an Ebb and Flow system a tray system is located above the nutrient solution. The tray is usually filled with a growing medium (Rockwool, Coconut fibers etc). A timer triggers the pump to start filling up the trays any solution not absorbed by the plants flow down back to the reservoir.

Tips when using and Ebb and Flow system:

  • Make sure your pump will allow the flow of the nutrient solution.
  • Make sure your tables are completely level as to not have the solution pool on one side. The table you use to set the trays on must be sturdy enough when the trays are empty and filled and can support the weight.
  • The trays should be flooded at least 4x a day and more on hotter days. Make sure to flush system periodically to wash fertilizer salts.

Deep Water Culture: (Bubbleponics)
This technique involves the suspending of plant roots over a nutrient and oxygen rich solution. Traditional methods favor the use of plastic buckets with the plant contained in a net pot suspended from the center of the lid and the roots suspended in the nutrient solution. An air pump is then used with airstones to create the oxygen rich solution. The advantages of using Deep Water Culture and Bubbleponics are that plant growth is significantly increased in the first couple weeks. Once the plant roots reach the reservoir there is no advantage to increasing growth.

Nutrients

Plants require over a dozen different elements in order to grow. Hydroponics nutrient solutions follow the same basic principles as soil fertilizers, in that they are designed to contain all of the nutrients that a plant would have normally received from soil. Most nutrient solutions are sold as a concentrate. Some come as powder, others as a liquid. Most are sold in two different varieties one for the “grow” stage and one for the “bloom” stage. Some hydroponics gardeners prefer to fertilize their plants organically. This can be done, but it is significantly more work than using chemical nutrients. Organic fertilizer compounds are prone to causing blockages in pumps and tubes.

What Each Nutrient Does:
Plants need a wide range of nutrients to maintain their health. Here is a brief rundown of each major nutrient, and what function they serve:

  • boron – aids in carbohydrate breakdown and the maintenance of healthy roots and shoots
  • calcium – affects cell permeability
  • copper – a key component in some enzyme systems
  • iron – plays an important role in transpiration and photosynthesis
  • magnesium – activates phosphate transfer
  • manganese – activates enzymes of aerobic respiration
  • molybdenum – allows plants to perform nitrate reduction and nitrogen fixation
  • nitrogen – a component in alkaloids, amino acids and chlorophyll
  • phosphorous – a part of some proteins and phospholipids
  • potassium – moves into areas that are growing quickly
  • sulfur – a component of proteins
  • zinc – though toxic in large amounts, zinc is required for normal growth in plants.

Growing Media

Soil is nowhere to be found in a hydroponics garden, but that doesn’t mean that plants grow in pots of nothing but water. Plant roots need to be anchored by something. A number of different inert materials are used by hydroponics gardeners to take the place of soil and provide the support that roots need. These materials are refereed to as “growing media.” Rockwool and the combination of perlite and vermiculite are the most popular media in which to grow plants hydroponically. Other growing media options include coconut fibers, clay pellets, sand, gravel, and even common polystyrene packing peanuts. Each different medium has its own advantages and disadvantages. The best media are generally the ones that provide the most support for roots while still allowing for the free flow of air, water and nutrients.

  • Rock Wool – the most widely used medium in hydroponics. Rock wool is an inert substrate suitable for both run to waste and recirculating systems. Rock wool is made from molten rock that is spun into bundles of single filament fibers.
  • Clay Pellet – Aanother a popular use of growing media. They clay is formed into irregular or uniform pellets and filtered in a kiln making it porous and lightweight. The advantage of using clay pellet is the ability to reuse the pellets after being sterilized after each use.
  • Coir – is the leftover material from the outermost shell of the coconut. The advantages of coir are that it is organic. It is extremely difficult to over water coir due to its perfect air-to-water ratio, plant roots thrive in this environment, coir has a high cation exchange, meaning it can store unused minerals to be released to the plant as and when it requires it.

Lighting

High Pressure Sodium
High pressure sodium lamps, or HPS lamps, emit light that is in the red-orange part of the light spectrum (even though it appears to humans as a yellowish white). Traditionally, they have been used by hydroponics gardeners as secondary lights. Often, they are placed inside a greenhouse to supplement natural sunlight. HPS lamps produce a light that stimulates budding and flowering in plants. Because of this, they are mostly used by commercial hydroponics grow operations that produce fruit.

Metal Halide
Metal halide hydroponic lighting lamps have an advantage over many other types of other lamps here, since they can produce the best white that is closest to the sun’s light color. Metal halide lights produce a wide range of light from the blue end of the light spectrum. Because of this, they make an excellent light source for hydroponically-grown plants, which crave this kind of light. Young plants and leafy greens like lettuce and spinach particularly benefit from the blue light emitted from metal halide lamps. Many hydroponics gardeners use nothing but metal halide lights, because they are considered to be the best overall artificial light source for promoting plant growth in an environment with little or no natural light. Some gardeners (particularly commercial growers) combine metal halides with high pressure sodium (HPS) lights, which emit colors in the red end of the spectrum and are great for plants in their flowering stage.

Light Spacing

  • 175w HID: covers 2×2 area and shouldn’t hang farther than a foot from plants.
  • 250W HID: covers a 3×3 area and should be spaced 12-18in above plants.
  • 400W HID: delivers enough light to cover a 4×4. Light should hang 12-24in
  • 600W HPS: will cover a 4×4 area also. It should be hung 18-24in above plants.
  • 1000w HID will illuminate a 6×6 area. Large 1000w can burn foliage if hung closer than 24in.

Fluorescent
Can be used for indoor gardening, but they are not very efficient and will never produce enough light to compare to HID lighting. However, they are a popular choice for many small gardeners due to their availability, low price, compact size, and low heat emission. Because of their low heat emission and soft light intensity, fluorescent grow lights can be very effective for low-growing plants (lettuce, spinach, etc.) or plants that need indirect light burning the tips should not be an issue when using compact fluorescent grow lights, so you can get the lights very close to the top of your plants.

Compact Fluorescent
Can be used for indoor gardening, but they are not very efficient and will never produce enough light to compare to HID lighting. However, they are a popular choice for many small gardeners due to their availability, low price, compact size, and low heat emission. Because of their low heat emission and soft light intensity, fluorescent grow lights can be very effective for low-growing plants (lettuce, spinach, etc.) Burning the tips should not be an issue when using compact fluorescent grow lights, so you can get the lights very close to the top of your plants.

Cloning
Cloning allows the gardener to replicate a genetically identical plant from a parent plant. The clone will have the exact same characteristics as the mother plant, the same growth habit, disease resistance, fruit shape, flower color and yield potential
Factors that influence success on cuttings:

Parent Stock
The condition of the parent plant is an extremely important factor to consider when taking cuttings from a particular plant. If the mother plant is infested with insect pests, root rot and/or mold she will be stressed, and thus the quality of the cuttings will be poor. The insect pests and disease will be transferred to your garden creating more problems later on. Never select a plant to be a mother if it is lacking in vigor. Cuttings from these plants will always produce bad clones, slow rooters, susceptible to disease and lower yielding. Always select parent stock that has the best disease resistance, pest resistance, most vigorous, most suitable growth habit and of course the highest yielding.

Rooting Medium
There are many types of rooting mediums that are available to the gardener. The most common used is Rockwool. The Rockwool is presoaked in a ph5 solution; it is then drained but kept moist. Keeping it oversaturated will cause the roots to rot and lead to death of the plant.
Rooting Hormone. Rooting hormone is used in the starting of roots from a cutting. The most common products are Rooting Gel, Rooting Powder and products such as Superthrive.

Water Quality
Water quality is often over looked in the cloning process. The best water to be used is Spring water and Reverse Osmosis water. They have just the right amount of minerals that wont be too toxic for the cuttings. Tap water has too many impurities that will usually cause harm to the plant.

Temperature
The ideal temperature range for cuttings is 72°F – 80°F. It is always better to have the root zone temperature at 76°F – 80°F while the canopy is kept at 72°F – 80°F. The warmer rooting zone helps produce roots quicker. If the rooting zone is too cold, especially during the winter months, then the cloning system should be placed on a heating mat that has a thermostat control set to 80°F. In winter, when the water temperatures in the pipes are cold, take care to allow the water to reach room temperature before adding it to the cloning system. Cold water on the cuttings or young roots will shock the clones and hinder their rooting abilities.

Humidity
Having the correct humidity is important for successful cloning. The ideal humidity range is between 70-80%. Low humidity will cause the young cutting to transpire and loose more moisture than what it can absorb which kills cuttings.

Light
Selecting the correct lighting is important to the cutting. The best type of light to use is fluorescent. Fluorescent light has the correct balance of blue and red spectrum and is also a soft light. The softer, less stressing source of light is important to the cutting in the early stages of life when stress is high due to being cut away from the mother plant and no roots have yet formed. The most common lighting pattern for clones is either 18 hours or 24 hours of light. Using the 18 hour light pattern allows the plants a 6 hour period of darkness; this is when the plant converts its sugars into starch. This starch is then stored in the roots. Providing a dark period will help a healthier root system to develop. If possible avoid using HID lamps as a cloning light; these lights are too intense and produce too much heat for cuttings.

Temperature and Humidity
The best temperature for most plants is somewhere between 73 and 82 degrees Fahrenheit for daytime. At night you should keep the temperature between 54-62 degrees. If you grow plants inside your house, you do not need to heat the entire building to this temperature. The lights in your grow room should boost the temperature inside the room higher than normal room temperature
Humidity is also a concern in a hydroponics garden. If humidity gets too high for a prolonged period, it can encourage the growth of various moulds that will damage your plants. If humidity gets too low the leaves and roots will begin to wilt. Different plants grow best in different levels of humidity, so before you plant your seeds it is smart to find out what level of humidity your plants will require. The ideal humidity for a normal plant is around 50 percent. To help keep humidity down, clean up any water that spills out of your watering mechanism.

Air Circulation
Though it is often overlooked because we don’t see it in front of us, the air around our plants plays a vital role in how well they will grow. In fact, the air that circulates in a grow room is just as important to a plant as lighting and mineral solution. In outdoor gardens air circulation is provided by nature, but in an indoor hydroponics garden the gardener must take charge. In closets or other small, enclosed places, a small household fan should meet your circulation needs. In rooms around ten feet by ten feet, an industrial-strength fan will need to be added in addition to the household fan. Larger spaces will require more fans. The best fans to use for smaller are oscillating fans which will more the airflow all over the room rather than in the same area. Carbon dioxide, or CO2, is an essential nutrient for all plants. To make sure there is enough CO2 for your plants, you’ll need to have an outside source of air coming into the grow room. If this cannot be done, you will need to purchase a CO2 generator.

Insect and diseases
One of the main advantages of hydroponics gardens is that they can be situated indoors, away from many of the animals, insects and pathogens that wreak havoc on outdoor crops. However, they are still not immune to pests – in fact, there are some pests that can affect indoor plants more severely than outdoor plants. It is important for every hydroponics gardener to become educated about common pests and how they can be controlled. All the money you spend on lights and tables, and the time you spend experimenting to determine the ideal nutrient solution mixture, can quickly go to waste if your garden is infiltrated by pests.

Most common houseplant insects: 

  • Spidermites – tiny specks that cause yellowish white spots on the top of leaves
  • Aphids – size of a pinhead and easy to see with the naked eye. They suck plant sap and causes the leaves to wilt.
  • Whiteflies – they are a small white moth. Eggs are found on the leaf undersides.
  • Thrips – tiny winged thrips are hard to see and easy to spot. Shake a branch and if white gray dark thrips they will run. They scrape plant tissue and the juices off.
  • Fungus Gnats – small winged flies that grow 4-5mm long that infest growing medium eating and scarring roots.

Common Diseases:

  • Gray Mold – flourishes in moist temps climates and is fatal. It appears as brownish spots on stems and flowers in arid climates.
  • Damping off – prevents sprouted seeds from emerging. Seedlings and cuttings rot at soil line. Foliage in older plants yellow and stems rot.
  • Green Algae – grows on moist Rockwool and other moist growing mediums. It causes little damage but attracts insects and fungus gnats.
  • Powdery Mildew – small spots on the tops of leaves progress to a fine pale gray/white powdery coating on growing shoots leaves and stems.
  • Root Rot – turns roots dark brown, slows growth leaves discolor and then later wilts the entire plant. Products such as copper soap, or other spray applications for foliage can be applied to soil or topical.

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