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Hydroponic plants: the ultimate guide

Hydroponics is the process of growing plants above ground. You have control over the entire environment of your crops. There are several types of hydroponic systems (nutrient film, tidal table, deep water culture, etc.), which you can grow outdoors or indoors. Each system has its own needs as materials.

These are techniques that allow you to have year-round plants that are difficult to grow, such as lettuce, basil and other herbs. You can also use these techniques to make a green wall.

Soil culture has several drawbacks: you have to deal with weeds, insects, diseases, sometimes it doesn’t work without really knowing why and, above all… you have to have the space! Indeed, not everyone has a fertile garden square that can accommodate his salads.

Soil-less agriculture, called hydroponics (hydro, water; Ponos, work) is an interesting solution to make your life easier and to grow plants in very small spaces. Since your plants are in a controlled environment, you know exactly what to do to make them mature and you can largely automate their maintenance.

Note that you can’t grow larger vegetables or roots, such as potatoes or pumpkins. That still leaves plenty of plants: salads, herbs (mmmh basil), strawberries, zucchini, tomatoes … There is plenty to do!

You will discover here how to do it. We will first explain the main lines of hydroponics, before studying the practical aspect: what are the choices open to you and how to make them.

I. Understanding Hydroponics

Hydroponics, while it may seem new to many, is in fact a very old practice. For example, the famous gardens of Babylon would have been cultivated using hydroponics. In the same way, the Aztec city of Tenochtitlan would have cultivated part of its food on rafts soaking in the lake Titicaca. Hydroponics has recently been the subject of renewed interest, as it is generally done without pesticides.

To help you understand hydroponics, you need to know its equipment, consumables and systems.

The different hydroponic systems

There are many different hydroponic systems. Here are the main ones:

  • The Kratky method is very simple to set up: in a container, the roots of the plant fall into the nutrient solution.
  • The wick system is identical to the Kratky method, except that the nutrient solution is in an independent tank and a wick dipping in it transmits the nutrients to the roots.
  • The deep water culture (DWC) consists in immersing the roots of the plants in the nutritive solution and to supply it with oxygen thanks to an air pump.
  • The Ebb&flow table imitates, as its name indicates, a tidal system: the nutrient solution passes from a tank to the table where the roots of the plants are bathed.
  • The drip system consists in watering the plants with a drip irrigation with the nutritive solution.
  • The nutrient film technique (NFT) consists of placing the plants on a table with a slight inclination and letting the nutrient solution flow gently to the base of the roots.
  • Aeroponics involves spraying the nutrient solution onto the roots.

The first two are so-called “passive” hydroponic systems, because no pump is needed to operate them. They are less expensive and require less electricity.

To go further, I suggest an article on hydroponic systems.

The hydroponic equipment

Once you have chosen your system, you can choose your infrastructure: where your crop will take place. It can be a horizontal or vertical pipe, a table with gutters or a myriad of other formats, depending on the hydroponic system you choose.

Next, you will need to choose a growing medium: what substance will “hold” the roots of your plants? Here are some examples of inert substrates (i.e. they do not interact with the plant or the water):

  • Clay balls
  • Rockwool
  • Perlite
  • Coconut fiber

Finally, you will have to manage the environment of your crop. This includes air and/or water pumps, pH and electroconductivity monitors, fans, lighting, etc. In short, everything you need to make your plants feel “at home”.

To go further, you can consult our page on hydroponic equipment.

Plant nutrition

Normally, plants find their nutrients in the soil. In hydroponics, you will have to bring them diluted in an aqueous solution: the “nutrient solution”.

Plants need many different nutrients to grow. First, there are the macro-nutrients, which you may have heard of: NPK (Nitrogen, N; Potassium, K; Phosphorus, P). There are also many micronutrients, such as molybdenum (Mo), zinc (Zn) or copper (Cu). Finally, the solution must also have good electrochemical properties, including acidity (pH) and electroconductivity (EC).

Exceptionally, if you grow outdoors, you may want to protect your plants from insects and diseases. There are specialized plant protection products for this.