The Fundamentals of a Hydroponics System
Understanding Vegetative Growth and Flowering / Bloom cycles
Plants undergo a number of changes throughout each life cycle. The two most distinctive are Vegetative Growth and Flowering / Bloom. During vegetative growth the plant will concentrate its energy on root formation and growing vertically towards it energy source (either the sun of lighting), it will also so significant increase in foliage. During the Flowering / Bloom stage the plant will undergo a short burst of intensive Vegetative growth which then initiates flower set. These flowers then move along to provide fruit, which will fill out and ripen in the late stages of bloom.
How many light hours does a plant require?
As a general rule for vegetative growth a plant will require long periods of light, this is generally considered to be 18 hours. For the flowering / bloom the lighting hours can be reduced to 12 hours.
Temperature- The optimum day time temperature range is 26⁰C to 28⁰C. While the optimum lights off (night) temperature for vegetative growth requires a drop of no more than 6⁰C to 8⁰c. During the flowering /bloom period the temperature drop should be no more than 10°C to 12°C.
Root Zone Temperature
This is dependent on the type of crop, but as a general rule 18⁰C to 22⁰C is ideal range. For Winter crops use the lower end of the range and for tropical crops use the warmer end of the range. This also applies to the water temperature of the nutrient solution.
Ideal Humidity
As a general rule 40% to 65% is optimum. The conditions to consider in this situation is if the humidity is too high the breeding rates of pathogens will increase, as to will the probability of mould, botrytis, fruit rot and powdery mildew.
Amount of lighting required
For optimum growing conditions using High Intensity Discharge (HID) lighting, 600 to 800 watts/m2 is optimal. It is also important to consider a number of criteria when choosing a light source, such as Photo synthetically Active Radiation (PAR, which is the light a plant can actually use), intensity, spectrum and ballast efficiency.
System Hygiene
Just like humans plants are prone to disease and pest attack. The best form of protection is prevention. Keep your system clean by continually sanitizing. The best option for this is to use beneficial micro organisms instead of chemical sanitizers, which are generally harmful to the plants.
Air movement
As part of photosynthesis and respiration plants require CO2 and Oxygen to survive. The simplest way to do this is to continually exchange the air within the room. As a minimum it is important to exchange the air in the room at least once every 15 minutes.
Guidelines to Growing Medium Selection
Careful consideration must be given to this choice as there are many variables involved. As the grower you must consider the type of system. As a general rule Coco coir is the most forgiving medium and will deliver optimum results as it has a good water holding capacity and a high porosity to allow Oxygen in. On the other hand there is Expanded Clay which is also a good medium but is better suited to systems that continually water as it has a low water holding capacity, but has an extremely high porosity.
The Seven Key Aspects of hydroponics
These are all the conditions that as a grower you must control to maximize your yield. They are, Medium, System, Lighting, Environmental, Feeding Regime, Plant and Grower. Remember your results will only be as good as your weakest link, so don’t ignore any of these variables.
Trouble Shooting
Over watering
This is one of the most common issues in hydroponics. It can be noticed by yellowing of leaves from the bottom of the plant or slow growth. Over watering will starve your medium of Oxygen, increase the likeliness of disease, cause root problems, pests and reduce growth. In mediums such as Coco Coir short feeds of approximately 1 to 2 minutes scheduled 4 to 5 times during the lights on period should be ideal. This is based on approximately feeding each plant 4L to 6L daily with a run off of 10 to 15%.
Salt build up
This is common in recirculation systems. It will generally show up as the tips of the leaves burning. This is easily solved by just flushing out the medium with fresh water, this is also an excellent time to use Fulife.
Flowers rotting
This is caused by a pathogen called Botrytis. The best solution for this is to use the beneficial micro organism Bioxy which will feed on the pathogen. For best results it is also essential to reduce down the humidity on the growing environment.
Leaves curling over
This is generally due to incorrect pH levels, but can also signify Calcium deficiency. In this instance it would be ideal to flush your medium with fresh water and start adjusting the pH more frequently. It may also be beneficial to measure the waste pH to adjust the tank accordingly.
Purpling of leaves
This generally occurs during late bloom and is due to a deficiency of Phosphorous. In this instance adjust the pH to approximately 6.4 and use X10 Boost as delivery system and Alaska Pure as a natural Phosphorous source.
What to do if you have rot root
Dose the plants with a fungicide and allow 4 days for it to leave the system. To aid in the recovery and promote rapid root development dose with Nf Zyme and X10 Boost.
Frequently Asked Questions
What is PH?
pH is defined as the degree of acidity/alkalinity of a solution. It is identified on the pH scale ranging from 0 to 14, with a pH of 7 representing the neutral point. Solutions with a pH less than 7 are considered acidic, while those above 7 are considered basic (alkaline). The pH scale is logarithmic, meaning small changes in pH represent large changes in the degree of acidity or alkalinity. For example, a solution with a pH of 5 is ten times as acidic as a solution with a pH of 6, but a solution with a pH of 5 is 100 times as acidic as a solution with a pH of 7. For plants this is relevant, as the majority of plants will undergo maximum unassisted uptake of nutrient in a pH range of 5.8 to 6.3.
Foliar feeding and its importance
Foliar feeding is the technique of applying liquid fertiliser directly to the plants leaves. Clinical research has shown that plants absorb nutrients from foliar feeding at the rate of approximately 30cm per hour to all parts of the plant. Foliar feeding is considered especially useful for introducing trace elements, or for the emergency feeding of plants which are found to have a specific shortage of a particular element. In some cases, as with the example tomatoes, it's actually believed that foliar feeding during flower set causes a dramatic increase in fruit production.
It must be considered that foliar feeding alone will not satisfy your plants nutrient requirements. This is because foliar absorption is limited by the relative barrier of the cuticle.
How to foliar feed
It is possible to use any full spectrum nutrient to foliar feed your plants, but it is advised that the nutrient be organic or organic based. To avoid nutrient burn the foliar nutrient solution strength should be no more than 1/3 of the manufacturers recommended dosage for root zone feed programs. The ideal temperature to foliar feed at is approximately 22ºC. This is the temperature when stomata on the underside of the leaves are open, at temperatures above 28ºC the stomata may not be open at all. This would deem the foliar feed ineffective. Keeping this in mind, it is important to foliar feed during the cooler parts of the day. For optimum results and to prevent burning it is best to foliar feed early in the morning or late in the afternoon.
It is important to foliar feed with a high quality sprayer, the sprayer must be able to atomise the solution into a very fine mist. Also ensure that the pH of your solution is adjusted to between 6.2 and 7. During the feeding process, it is important to spray both the top and underside of the leaf surface until the liquid begins to drip off the leaves. At a minimum foliar feed once a week and if there is any white residue found on the leaves rinse the foliage with pH adjusted water to reduce salt build-up.
What is Root Rot?
Root Rot is a condition generally suffered by plants root systems due to poor soil drainage or over watering. The excess water makes it difficult for the roots to get the air that they require, making them rot. Root rot is best prevented or controlled as there is no cure.
The most common form of root rot is due to Pythium spp. When severe the lower portion of the stem becomes slimy and black. Usually, the soft to slimy rotted outer portion of the root can be easily separated from the inner core.
What are the essential elements/nutrients for plants?
There are sixteen essential nutrients which plants require. Three are directly absorbed from the atmosphere (Oxygen, Carbon and Hydrogen). While the other thirteen essential elements must be absorbed through your plants growing medium. The list of thirteen elements is further broken down into three key groups. They are defined as macro, secondary and micro nutrients.
Macro nutrients include Nitrogen (N), Phosphorus (P) and Potassium (K). These are the key elements required for plants throughout their life cycle. Nitrogen is an essential component of amino acids and, therefore, of proteins which include nucleic acids, enzymes, and the green, light-harvesting pigment, chlorophyll. It is also the nutrient which normally produces the greatest yield response in crop plants.
Phosphorus is an essential part of the enzymes which help the crop to fix light energy. It forms an integral part of nucleic acids, the carriers of genetic information, and is important in stimulating root growth.
Potassium is involved in processes which ensure carbon assimilation and the transportation of photosynthates throughout the plant for growth and the storage of sugars and proteins. The potassium ion is also important for water regulation and uptake.
The secondary elements are equally as important but are required in smaller quantities. These include Magnesium (Mg), Sulphur (S) and Calcium (Ca). Magnesium occurs in chlorophyll and is also an activator of enzymes, while sulphur forms part of two essential amino acids which are among the many building blocks of protein. It is also found in vitamin B1 and in several important enzymes. Calcium is required for plant growth, cell division and enlargement. The growth of root and shoot tips and storage organs is also affected by calcium as it is a component of cell membranes. Calcium is also vital for pollen growth and to prevent leaf fall.
Finally, there are micro nutrients these are equally as important but are only required in minute quantities. These are Iron (Fe), Manganese (Mn), Zinc (Zn), Boron (B), Copper (Cu), Molybdenum (Mo) and Chlorine (Cl).
What are plant growth regulators?
Plant growth regulators are also commonly known as plant hormones and phytohormones. They are various hormones that control or regulate germination, growth, metabolism, or other physiological activities. They can be produced by the plant or be used as an addition to achieve a growth response.
Plant growth regulators are active in very low concentrations in plants. They are produced in certain parts of the plants and are usually transported to other parts where they elicit specific biochemical, physiological, or morphological responses are required. They are also active in tissues where they are produced. Each plant hormone evokes many different responses. Also, the effects of different hormones overlap and may be stimulatory or inhibitory. The commonly recognized classes of plant hormones are the auxins, gibberellins, cytokinins, abscisic acid, and ethylene.
What is photosynthesis?
Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar. This process mostly occurs in plants and some algae. The conversion of unusable sunlight energy into usable chemical energy, is associated with the actions of the green pigment chlorophyll. For the conversion to occur plants require light energy, CO2, and H2O.
Photosynthesis takes place primarily in plant leaves, and little to none occurs in stems, etc. The parts of a typical leaf include the upper and lower epidermis, the mesophyll, the vascular bundles (veins), and the stomata. The epidermal cells do not have chloroplasts, thus photosynthesis does not occur there. They serve primarily as protection for the rest of the leaf. The stomata are holes which occur primarily in the lower epidermis and are for air exchange: they let CO2 in and O2 out.
Should I remove leaves to allow more light to enter?
The general rule is that leaves are sugar production factories for plants and that the sugar is critical for the flowering process. So, always refrain from removing leaves from your plant.
How do I measure the strength of my feed solution?
There are a number of different measures available to measure the strength of nutrient solutions. Each of the methods relates back to the Electrical Conductivity (EC) of the solution. The Electrical Conductivity is a measure of a material's ability to conduct an electrical current.
When an electrical potential difference is placed across a conductor, its movable charges flow, giving rise to an electric current. The conductivity is defined as the ratio of the current density to the electric field strength.
Other common measurements used to define nutrient strength are the Conductivity Factor (CF), Total Diluted Solids (TDS), and Parts Per Million (PPM).
What food strength should I be using?
Every plant is different, but as a general indication the following table shows the required food strength for most plants during various life cycles.
| Plant Life Cycle | Recommended E.C Readings |
| Root formation | 0.7 - 1.2 |
| Vegetative growth | 1.0 - 1.5 |
| Early bloom | 1.2 - 1.7 (1st & 2nd week) |
| Bloom | 1.2 - 1.9 (3rd & 4th week) |
| Late bloom | 1.0 - 1.6 (5th, 6th & 7th week) |
| Final bloom | Lower your EC (8th week) |