The Beginners’ Guide to Hydroponics

This beginners’ guide to hydroponics is an introduction to the subject of hydroponics and is designed to give anyone both the basic scientific background surrounding this technology and also the practical information you need to begin your own hydroponics installation, explaining the way why certain things are done as they are and the pros and cons of the various methods used throughout the process.

What is Hydroponics?

Hydroponics is a type of horticulture (and a subset of hydroculture) in which plants of many different kinds can be grown completely without soil, by using a nutrient solution in a water-based medium.

The term ‘hydroponics’ was first coined by William Frederick Gericke from the Greek words ‘hydro’, meaning water, and ‘ponic’, meaning to cultivate or to work. Hence hydroponics is the technology of making water work in the process of cultivation.

Examples of the usage of hydroponics can be seen as early as 600 B.C. in the Hanging Gardens of Babylon, but Hydroponics, as it was understood as science properly, started in the early seventeenth century when it was discovered that there were many advantages to using cultivation methods without the need to use soil. In fact, hydroponics is far more efficient than traditional forms of cultivation, in all sorts of ways.

As time went on, hydroponics developed as a technology with several different disciplines within the overall process, each with its own advantages and disadvantages relative to the other. The fact that there are different ways of going about it is to the great benefit of the beginner, who is now able and empowered to select the best and easiest methods available and to get started with minimum effort and expenditure.

The Advantages of Hydroponics

There are several advantages of hydroponics over more traditional soil-based cultivation methods. These can be outlined as follows:

Efficient Water Usage. A huge advantage in cases where water supply is very sparse, hydroponics has been measured to be up to 90% more efficient than soil-based cultivation in its use of water. This is because the process conserves water consistently in an almost closed system.

Efficient Land Usage. As well as conserving water, hydroponics makes far more efficient use of the land available for cultivation, with amazing yields of between three and ten times that of traditional methods for the same amount of land available.

Speed of Cultivation. A large number of different types of crops can be produced twice as fast as traditional methods of cultivation in a well-managed environment. This also means that the nutritional value of the crop is twice as much, given that the time taken to grow the crop to harvest is effectively halved.

No Need for Good Quality Soil. The very nature of hydroponics means that soil quality is irrelevant as no soil is needed. This is a huge game-changer in places where horticulture was previously impossible.

No Need for Good Climate. Similarly, with a system such as hydroponics which can ideally be managed indoors, there is no need to worry about whether the outside weather conditions are favourable or not; in fact, the weather itself becomes irrelevant.

Far Less Danger of Disease. Without the need for soil, the crop is in no danger of contamination or blight by earth-born pests and diseases which can destroy whole harvests with traditional methods. There are also no weeds to take care of in the process.

No Need for Chemicals. Because of the above, there is no need for using potentially dangerous chemical pesticides in hydroponic methods in order to keep down pests and eradicate weeds. Such chemicals can run off into the water table and enter the local water supply, sometimes with regrettable and long-term consequences. Hydroponics does away with that.

Minimal Work Needed. In a well-ordered hydroponic process, what you have is essentially an almost closed system that needs very little maintenance; it does not require the regular drudgery of weeding and the tilling of the soil. Instead, you only need to make occasional checks to make sure that each part of the system is running according to the optimal conditions which are already known and easy to apply and regulate with readily obtainable and inexpensive equipment.

Scalable System from the Very Small. You can start your own hydroponic cultivation system with a very small setup in a corner of a spare room or even a cupboard. This is ideal for the beginner, of course. Different hydroponic systems will allow different economies of scale and choosing the right type of system will determine the ease that you can scale upwards to as large a system as you like, remembering all the time that even a relatively small setup will yield much more than a comparably sized soil-based process.

The Six Types of Hydroponic System

There are six basic types of hydroponic processes and systems. These are Wick, Water Culture, Flood and Drain, Dripper System, Nutrient Film Technique and Aeroponic. Let’s examine each of these in more detail.

Wick System. Considered to be hydroponics at its simplest, the wick system uses a small pump to move the nutrient solution from the reservoir to the plants housed in the grow tray. It is a passive system in that there are no moving parts. This technique is ideal for beginners; such a setup can be made as a simple DIY project and there are several ready-made commercial types available as well.

Water Culture. Sometimes also known as Deep Water Culture or DWC, this type of hydroponic system employs the suspension of net pots containing the plants in the reservoir so that the roots are constantly submerged in the nutrient solution.

Flood and Drain. Also known as Ebb and Flow, this uses a timer to activate a pump that exposes the plants within the grow tray to the nutrient solution every few minutes, after which the nutrient solution drains back into the reservoir.

Drip System. Here a timer is also used which allows the nutrient solution to be drawn through its network of drip lines. There is a ‘recovery’ and a ‘non-recovery’ version, where the excess nutrient solution is (or is not) collected back into the reservoir to be re-used. This is probably the most widely used type of hydroponic system in the world.

Nutrient Film Technique. NFT is a type of hydroponic system which works by constantly flowing the nutrient solution through the grow tray (which is usually tubular) so that there is no need for any timer. The nutrient solution then flows back into the reservoir. This system has no need for any growing medium.

Aeroponic. Like the Nutrient Film technique above, this hydroponic system does not need a growing medium, because in this case, the plants hang in the air. A timer controls the rate at which the nutrient solution is sprayed onto the roots of the plants. This misting of the roots happens every few minutes. Because the roots are suspended in the air it is important that the power supply is never interrupted, even for a short time as typically happens in a power cut, as this will cause the roots to dry out relatively quickly.

It is considered that the wick system is the easiest hydroponic setup for beginners; the Deep Water Culture system is also favoured because of a well-known commercial variant called the Kratky method, which is easily set up and also inexpensive.

The Chemistry of Hydroponics

All plants work by consuming carbon dioxide and giving out oxygen as a by-product. This is exactly the opposite of what humans do in making use of the oxygen in the air we breathe and then breathing out carbon dioxide, so people co-exist with plants perfectly in this symbiotic way.

In broad terms, all plants need oxygen, light, water and nutrients. The combination of these sets in motion the chemical process known as photosynthesis, which is the process in which (green) plants make use of light in order to synthesize nutrients from carbon dioxide and water. Thus plants ‘drink’ the CO2 and water and give out oxygen. The process of photosynthesis in plants, in general, involves the green chlorophyll and generates oxygen into the air as a by-product.

The nutrients which are used in the hydroponics process contain the main elements Nitrogen, Phosphorus, and Potassium (collectively N-P-K) which all plants need to be able to grow.

All plants use sunlight in order to manufacture food in the form of sugars through the clever use of the photosynthesis process. The energy of the sunlight is stored in the green pigmentation of the leaves called chlorophyll.

The chemical reaction is, specifically:

Carbon dioxide + water + light = glucose + oxygen

The carbon dioxide reacts with the water contained in the plant roots (this process uses sunlight as a catalyst). Food in the form of sugar (glucose) is created from this process called photosynthesis. The glucose is then used for respiration in the normal life cycle of the plant. Alternatively, it can be stored for when it is needed later by converting it into starch.

Given that oxygen, water and light are all more or less constants, the variables which determine the success of your hydroponics project are the nutrients you decide to use. There are several different nutrients available commercially, but they all share the same broad characteristics because they must all serve the same purpose.

The nutrients used in hydroponics can be classified into two categories which are macronutrients and micronutrients.

Macronutrients and Micronutrients used in Hydroponics

In all types of hydroponic techniques, both macronutrients and micronutrients play their own important part in the process, and each is as important as the other in the way that they reinforce and complement the growing process.

Macronutrients

Macronutrients are the nutrients that plants need in relatively large amounts. Macronutrients include nitrogen (chemical symbol N), potassium (K), phosphorous (P), calcium (Ca), magnesium (Mg) and sulphur (S).

Nitrogen is the main plant growth food. Without nitrogen there would be no foliage; nitrogen controls the growth of the cells in both the stems and the leaves and also determines the colours and size of the plant. It plays a vital role in protein synthesis which involves chlorophyll, amino acids and their associated enzymes.

Potassium plays a vital role in all stages of plant growth. Crucially, potassium helps synthesize sugar, starches and carbohydrates, and plays its own part in the development of the plant’s stems, roots and flowers. Potassium is also important in resisting insects and bacteria.

Phosphorous is crucial in the process of photosynthesis and is part of the DNA of any plant, controlling all the plant’s aspects and characteristics. A lot of phosphorous is required in the early stages of plant growth and in germination, and it is responsible in large measure for the roots of the plant as well as its seeds, flowering and fruits.

Calcium is important in the development and formation of cells in a plant and is particularly important in fast-growing plants.

Magnesium is also used in relatively large quantities by faster-growing plants. Magnesium is vital to chlorophyll production and helps to allow oxygen to be created as part of the photosynthesis process. It is essential for vigorous and healthy plants.

Sulphur is a component of several of the amino acids which form proteins, hormones and vitamins.

Micronutrients

By contrast, micronutrients are needed in very small amounts but are nevertheless essential to a plant’s growth and healthy development. Micronutrients include zinc (Zn), manganese (Mn), iron (Fe) and boron (Bo).

Zinc works together with other elements to help form chlorophyll, which is any one of several related green pigments in a plant.

Manganese plays its own part in the production of chlorophyll along with nitrogen and iron.

Iron is crucial in relation to a plant’s enzyme system and is all necessary for the synthesis of chlorophyll.

Boron combines with the macronutrient calcium in the development of a plant’s cell membranes and the production of chlorophyll.

Other micronutrients include copper, molybdenum and chlorine.

Plants would find it impossible to build molecules or to enable the enzyme reactions which are necessary to a plant’s healthy development without all these essential elements. They are all vital in a plant’s healthy life cycle. The hydroponic process would not be able to compete or display its superiority to soil-based horticulture without these nutrients and without the cooperation of all these elements in their various proportions working together.

Growing Media Used in Hydroponics

The basis of hydroponics is that it is a form of horticulture that does not require soil. But in the absence of soil, plants will need a medium in which to successfully grow. There are quite a few different types of growing media available to the hydroponic gardener, and each has its own advantages and disadvantages relative to all the others.

The growing media should allow the transmission of moisture, oxygen and nutrients to the plants, especially the plant roots, and it is by its success in achieving this that any growing medium will be judged, along with its cost and ease of use. To this end, there are several growing media that are currently and popularly used.

In addition to supplying and holding oxygen, moisture and nutrients, a good growing medium should preferably be lightweight so that it can be transported easily and be easy to work with. It should be reusable and pH neutral (more about optimum pH values later), inexpensive and preferably organic and friendly to the environment.

Some popular media used in hydroponics include the following:

Coco Coir. Also known as Cocopeat, Coco-tek and Ultrapeat, this is widely used in hydroponics and is a by-product of the coconut industry, made from the husks of coconut shells. Coco coir can hold and retain air and moisture well, and it is environmentally friendly, being both organic and renewable. On the negative side, it does not have particularly good drainage properties and will, according to its quality, become uncompressed over time.

Perlite. This has been used in traditional gardening methods for a long time now. It is mined volcanic glass which is treated to very high temperatures. It is very lightweight, retains oxygen very well and is reusable. However, for some hydroponic systems perlite is considered too lightweight and there can be a certain amount of dust from the material.

Rockwool has had a number of popular applications and is made by melting volcanic rocks. The resulting compound is then spun into fibrous material as it emerges from the furnace. It is inert, holds water and retains oxygen very well, and can be used in a number of different shapes and sizes. However, it is not particularly environmentally friendly as it is almost impossible to dispose of, it is prone to particulate dust and lacks the pH neutrality which is preferred in such applications.

Expanded Clay Pellets. Also known as LECA, these are small spherical clay balls that are heat-treated until they expand to small pellets. This material has very good oxygen retention and is endlessly reusable. But it suffers from relatively bad water retention and is quite heavy when used in the kind of quantities which are necessary.

Growstones. These are very versatile porous rocks made from recycled glass. The material is lightweight and is more air and water retentive than both perlite and coconut coir. On the negative side, though, it is known to cause damage to some types of plant roots as it tends to cling.

Vermiculite, like perlite, is mined and treated to very high temperatures. It retails nutrients and moisture very well. But it is quite expensive, and it is known to retain too much water, although it’s often used in conjunction with perlite to partially correct this problem.

Starter Plugs. These are made from naturally occurring materials such as peat moss. It is ideally bio-adhesive and is good for seed germination and for plant propagation. It is, of course, organic and highly sustainable. But it can be fairly expensive and is only best used for cloning and for seedlings.

As you can see, there is quite a choice when it comes to growing media for your hydroponic system. The material you use will depend on personal preference as well as the type of hydroponic system you end up choosing.

The Best Grow Lights for Hydroponics

There are all sorts of grow lights available for use in hydroponics, and they come in a huge variety of different sizes, shapes and types. There are three main categories of hydroponic grow lights, and these are fluorescent, high-intensity discharge (HID) and light-emitting diode (LED). Each type, as you would expect, has its own pros and cons.

Fluorescent. This type of grow light, because of its cost and efficiency, is the most popular among home gardeners.

There are two types of fluorescent light: compact fluorescent light (CFL) and tube-style.

Compact Fluorescent Lights (CFL). These are recognizable as inexpensive bulbs which seem to be made to any imaginable shape. They are ideal for small hydroponic installations as they don’t give off large amounts of heat and can be safely put next to plants.

Tube-Style Fluorescent. These come in several different types. The T5, T8 and T12 seem to be the most numerous of these, of which the T5 are the most popular and are known for their efficiency. Tube-style lights are much wider than CFLs and are usually arranged in parallel and mounted on a fixed board.

High-Intensity Discharge (HID). HID grow lights are known to be more efficient than fluorescent lights. But they give off more heat as well, so they will quickly heat up and need constant ventilation.

High-Pressure Sodium (HPS). These emit reds and yellows of the spectrum. Because of these properties, they’re used more during the fruiting and flowering phases of plants, although they can also be used throughout the life cycle of any plant.

Metal Halide (MH). MH lights emit within the blue range of the colour spectrum. For this reason, these grow lights are best suited for vegetative phases of the plant life cycle.

Ceramic Metal Halide (CMH). Seeming much like conventional MH grow lights at first, CMH grow lights have a much broader spectral range than either MH or HPS and they last quite a bit longer than either of these other two types.

Light Emitting Diode (LED). LED grow lights are extremely efficient when compared with other types of light, and they give off a great deal of light while needing little electricity to do so. They are also extremely lightweight. They do not build up much heat, and in addition, many have built-in cooling facilities as well. LED grow lights consist of lots of diodes to produce their light; they can be customized to produce specific wavelength colours on the spectrum. The downside to LEDs is that they are relatively expensive (although over a long time they do pay for themselves as they need less electricity). LED arrays can also take up quite a bit of space.

Grow lights can be a large chunk of your hydroponics setup expenditure. For beginners who are on a budget, CFLs are a good choice. They work very well on smaller plants which require only a little light.

You may want to consider different types of grow lights at different phases of your plant’s life cycle. In terms of matching lights to plants, this makes a lot of sense. MH and CMH grow lights are best used during the vegetative phases and HP lights do better for the flowering phase.

For those with a larger budget to play with, LED grow lights are a good choice because, although relatively expensive as a one-off purchase, they pay for themselves because of their superb efficiency. They are also wide spectrum, so they suit all phases of a plant’s life cycle.

Because of the heat that your grow lights will inevitably produce, you will need to consider ventilation, for which there are various options. For those with a larger budget, you may want to invest in a water chiller; this will assure your plants’ optimum all-around condition.

The Best Environmental Conditions for Successful Hydroponics

You should take control of your hydroponics setup straight from the start and check regularly that everything is at its optimum setting. This covers all aspects of the hydroponics environment including such metrics as water quality, temperature, humidity, pH level and electrical conductivity.

Water Quality. The difference between water that is considered normal or optimal and water that is ‘hard’ can be important. The test for hard water involves testing for dissolved solids (TDS) in the water and is measured in milligrams per litre (mg/L).

In general, water which is anything up to 60mg/litre is considered ‘soft’. Between 60 and 120mg/L is considered moderately hard, between 121 and 180mg/L is hard, while water over 180 mg/L is considered very hard. City water, in its natural state out of the tap, is usually quite hard. If your city water is 200mg/L or over then it is too hard, so you’ll need to consider using filtered or distilled water instead.

Check here to discover the water type where you live.

Best Temperature. It is considered that any temperature in the range of 20 to 22 degrees Celsius is acceptable.

Best Humidity levels. The optimum humidity for hydroponics is in the region of between 50 and 60%. During the vegetative phase, when the plants grow plenty of leaves that need lots of water, the requirement for moisture is at its highest; in this phase, they do best at levels of up to 70%.

Best pH Levels. The optimum pH range for most hydroponic setups is from 5.5 to 6.5; the pH is quite important for plant growth as it affects the absorption levels of many of the 16 atomic elements which are needed for your plants’ healthy growth. The maximum absorption levels for these elements are considered to be at pH readings from 5.5 to 6.5, with a sweet spot at 6.0.

Electrical Conductivity (EC). Electrical conductivity measures the salts in your hydroponic system; also known as the level of nutrients in the system. An ideal electrical conductivity level would be somewhere from 1.2 to 2.0.

Because of their close association, electrical conductivity and pH meters are often to be found incorporated as one dual instrument or meter. You should measure both every few days or so.

Best Nutrient Solutions for Hydroponics

There are lots of nutrient solutions available for the keen hydroponic gardener, and the choice is basically determined by what you are actually growing. For many people, ‘nutrient solution’ and ‘fertiliser’ are interchangeable terms. So if you are growing spinach then you’ll be wanting a different nutrient to the one you’d buy if you were growing strawberries.

There are commercially available nutrients that are specially made up which you can buy off the shelf, or you can make your own nutrients, from your own formula. You can buy pre-mixed liquid or powder nutrients which are mostly sold as concentrates, then just add the water. Larger hydroponics growers and farms tend to favour their own mixes as they know that they have very specific needs for whatever it is that they are growing, and also the larger growers tend to have accumulated that much more knowledge and experience for them to be able to make those decisions and judgment.

Pre-mixed nutrients will generally come in concentrated form and in two separate containers; one of these will contain the macronutrients and the other will contain the micronutrients. Some of the elements can react together when mixed, hence the reason for separating them. When they are safely diluted this ceases to be a problem, as they do not form the precipitates which can occur when the concentrated elements are mixed. In some cases, you can buy the incompatible nutrient elements in their own single pack so that there is no danger of them mixing.

You will need a container to mix the nutrients in, a measuring container and something to stir the mixture. If there’s a lid on your mixing container then you won’t need anything to stir it with: you just shake it within the container as vigorously as you reasonably can. Although it can vary, the measuring quantity is generally 3.5mL of each of the concentrated forms per litre. Of course, before doing anything you should read the instructions, preferably twice.

Check the pH and the temperature. Go through each of the metrics one by one and get familiar with how each one ‘feels’; is there one process that demands more attention than the others? Does one aspect take more time than all the rest put together? Get to know the little quirks and turns of each aspect of the hydroponics process in sequence. Get to know the process personally; get to know its character and make it a friend!

How much solution do you want to make up? For beginners, it will be small to start off with. You’ll want to get a feel of things first; ideally, you’ll want to take things slowly, stage by stage. For people beyond the beginner’s stage, there are mixing drums that go up to 55 gallons.

As with everything else, you’ll want to get familiar with all the equipment and all the processes that go together to fulfil the project to its successful completion.