Growth Influencing Factors

Hydroponics is often referred to as controlled environmental gardening.  All conditions in a grow room are controlled by the grower.  The grower can simulate the seasons to replicate ideal growing conditions for any individual species. This may give some growers a bit of a God complex but where else can you play Mother Nature?

Artificial grow rooms offer a tremendous opportunity to produce maximum yields of selected plants at any time of the year.  Although the initial set up cost may seem a little steep, the high quality, wonderfully delicious produce you grow will quickly offset the expense.  Home grown hydroponic fruits and vegetables are a nutritious source of vitamin rich, flavour packed foods.

To successfully produce a bountiful crop in hydroponic culture requires some preparation.  Ideally the growing environment will start off sterile to eliminate any contamination from preexisting foreign matter such as bacteria or fungus spores.  All new equipment should be washed in a weak solution of bleach and water.  Equipment that has been used in previous growing applications needs a more thorough cleaning.  A disinfectant containing a viruscide and fungicide is recommended.

Since you are "Mother Nature" in your indoor hydroponic grow room you must recreate all of nature's fundamentals within its walls.  Wind, rain, sunshine, temperature fluctuations, light, day/night cycle and nutrition are all part of the simulated atmosphere in a grow room. These, along with oxygen (O₂), carbon dioxide (CO₂), potential hydrogen (pH) are what are termed Growth Influencing Factors or (GIF's) among hydroponic enthusiasts.   As in nature, you will need to find the perfect balance for each GIF and have all elements run in harmony.  If any of the GIFs are missing or out of balance growth will be compromised and entire crops may be lost.   The weakest link in the chain determines the outcome of your best efforts.

A diary or journal is an essential tool for a serious grower. Keeping precise records of fluctuations in the daily Growth Influencing Factors and their influences on crops is important.  It will help determine what is working and what is detrimental to plants. A daily record of such things as additives, reservoir conditions and other variables makes troubleshooting much easier and the implementation of corrective measures can be put into place swiftly, with minimal damage to crops. An accurate record will ensure that any problems are not repeated in subsequent crops. We have inserted a typical journal page that can be printed or a downloadable PDF just Click Here.

Take your journal with you the next time you visit your local hydroponic shop.  The experts there will be able to advise you if your crops are meeting their full potential and what you may be able to do if they're not.

The most important growth influencing factor (GIF) is light.  Lights range in size from 175 watt to 1000 watt.  A 1000 watt bulb will cover 16 to 25 square feet depending on the desired light intensity.  It is recommended that lights be used with a reflector to maximize the full use of the bulb's output.  A reflector will make sure all light is directed downward toward your plants and not wasted throughout the room.  The style and size of the reflector you choose will depend on the size of the lamp, desired light intensity and area of coverage. The most efficient way to use any high intensity light is with a light mover.  Lights can be placed closer to the crop, stems will be stronger and plant growth can increase up to 40%.  There are circular light movers that are capable of moving up to three lights at a time or linear light movers on the market today. 

Seedlings respond to continuous light.  Place seedlings in a humidity tent under a fluorescent bulb 24 hours a day.  Once the first true leaves appear remove tent and cut light time to 18 hours.  To propagate stem cuttings place them under a  6" humidity dome and provide 18 hours of fluorescent light.  Use a rooting hormone to ensure good root development.  This is a crucial time in a plants life.  Seemingly insignificant changes could indicate potential trauma to young plants.  Recoding dates and procedures during the germination or rooting stage will create a history and expectation for ensuing crops.

For optimum growth at maturity supply up to 18 hours of light followed by a 6 hour period of uninterrupted and complete darkness for respiration to transpire. Respiration must occur in every living cell if life is to be maintained and to allow a plant the ability to use energy and thus grow and produce flowers and fruit.  Respiration occurs mainly during the lights off cycle. Light requirements will vary with growth stages and different plants.

Timers are the easiest way to automate your grow room.  Plants will respond to an accurate day/night schedule and watering routine. With a timer you can establish a day/night schedule that suits your schedule; it is not necessary to conform to the outside environmental dark/light hours.  (Plug in fans, air pumps and drip irrigation pumps into the same timer as the light)

Nutrition is the second most important GIF and will be an integral part of your hydroponic gardening success.  Plants grow faster in hydroponics because their food supply is constantly available.  In the basic hydroponic system plants are fed by passing the nutrients over the roots or flooding around the root area at regular intervals, and then later draining off.  In a soilless mix plants can be hand watered from the top as you would with a regular soil container.

Electrical conductivity (EC), measured in milliMhos, is the measure of electrical conductance of the total dissolved solutes (minerals) in the solution.  The optimum EC range varies among different plants.  While EC measures the total dissolved minerals in a solution it does not identify the amounts of specific elements present. Therefore, it is easier to achieve the ideal EC using premixed 2-part hydroponic nutrient formulations than attempting to create your own formula using individual components.  It is necessary to change the nutrient solution weekly to ensure that plants receive the specific elements required.  Nutrient formulas may also be adjusted between the vegetative and flowering stages.  EC testers are the most accurate way of monitoring and maintaining a desirable nutrient level in your reservoir.

It is very important to keep track of any additives used for growth enhancement.  Note the date they are added and what effect they have.  Indicate any visible changes that occur immediately after additives are used, such as leaf colour or shape.  If a sudden adverse reaction takes place quickly flush or leach with a solution designed to rinse roots.

pH is the measure of alkalinity or acidity of the nutrient solution  and is an important consideration in hydroponics.  The ideal pH level for most plants is between 5.5 and 6.5. If the pH is not within this range plants will not be able to absorb nutrients at the maximum level.  pH should be tested on a daily basis using an inexpensive test solution or a pH meter. Even seemingly small pH fluctuations can have a big impact on plants ability to utilize nutrients.  The pH is easily adjusted with a pH Up or pH Down solution to obtain the desired level.  pH can be tested using a simple litmus paper or a pH meter may be used for exact digital readings.

Photosynthesis is the manufacture of sugar from two simple raw materials - carbon dioxide and water - in the presence of chlorophyll with sunlight (or artificial light) as the source of energy. Carbon dioxide (CO₂) is vital to the plants survival.  The normal atmospheric level is about 340 parts per million (ppm). Research has shown that plants are able to use more CO₂ than is available in the atmosphere (up to 1500 ppm) to grow larger and faster. CO₂ enrichment in your grow room has the potential to dramatically increase your yield with little cost.  A CO₂ injector should be used in conjunction with an exhaust fan to ensure all CO₂ is exhausted between cycles.  The injector should be installed above the lights because CO₂ is heavier than air and will float down through the plants, resulting in maximum intake.

It is absolutely essential to have good ventilation with an incoming supply of fresh air (oxygen) as plants will soon consume all the CO₂ in an enclosed environment.  Plants could not complete respiration or utilize the food produced by photosynthesis unless they have a good supply of oxygen.  An oscillating fan in the room will simulate the wind reducing ambient leaf temperature, restoring CO₂ to the leaf zone and strengthening the stems.  It will also make sure there is good distribution of fresh air throughout the room and help control humidity levels.

Atmospheric temperature must be monitored and controlled within the room.  As in the outdoors there needs to be an air temperature differential between the plant's perceived daytime and nighttime.  When there is light the plant considers it daytime and the temperature should be maintained around 18 - 25^oC and nighttime is 12 - 18^oC.  (This may vary slightly for different plants).  An independent thermostat should be placed among your plants to ensure temperature regulation. 

Plants grown hydroponically are usually strong and healthy making them less likely to fall prey to insect infestations. However there is always the risk of infiltration by some tenacious species of undesirable pest.  Biological controls such as lady bugs can be used to help safeguard crops against whitefly and thrips and beneficial predator mites may be used to help control spider mites.  With severe infestations non-systemic chemical interventions may be required.  Different methods of extermination are used for different conditions.  Conditions in you growing environment such as temperature will greatly affect the severity of the pest problem. Your diary will become an invaluable reference of all these variables.

Hydroponic gardening needn't be complicated.  However, if you wish to produce crops commercially or in large quantities journaling is strongly recommended.  Documenting successes and failures will help build a gardening history that will ensure your personal gardening growth. 

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