What is hydroponics? The simple guide to understanding and getting started
Hydroponics allows you to grow plants without soil by providing them directly with water and nutrients. Simply discover how it works, what you can grow, and how to get started at home.
Would you like to grow basil, lettuce, or even a few tomatoes at home, but you don’t have a garden or a balcony?
That is precisely where hydroponics becomes interesting.
The word may sound technical. Yet, its principle is surprisingly simple: growing a plant without soil by providing it directly with the water and nutrients it needs.
No need to turn your kitchen into a laboratory. To understand hydroponics, you must first start by understanding one thing: what a plant actually needs to grow.
What is hydroponics?
Hydroponics is a soil-free cultivation method.
Instead of developing its roots in soil, the plant receives the nutrients it needs through a solution composed of water and nutrients.
Depending on the system, the roots may be in direct contact with this solution or held in a neutral medium that simply helps the plant stay in place.
It is therefore a quite different idea from traditional gardening:
soil is not removed because it would be useless in nature. It is replaced by an environment in which water, nutrients, and root oxygenation can be controlled more directly.
It is indeed this soil-free cultivation, with nutrients provided in another way, that Penn State Extension and the Royal Horticultural Society use to define hydroponics.
Does a plant really need soil?
No.
A plant does not need soil as such to grow.
It primarily needs several essential elements.
☀️ Light
Light provides the energy necessary for photosynthesis.
Without enough light, a plant can stretch, weaken, or have its growth significantly slowed, even if everything else is managed correctly.
This is particularly important when growing indoors, where the natural light available behind a window is not always sufficient.
💧 Water
Water participates directly in the plant's functioning and, in particular, allows for the transport of nutrients.
But contrary to what one might think, roots should not simply be permanently immersed in just any conditions: they also need oxygen.
This is why hydroponic systems are designed to maintain a good balance between water, nutrients, and root oxygenation. The RHS notably emphasizes the importance of a properly aerated root zone in hydroponics.
🌱 Nutrients
Nitrogen, phosphorus, potassium, calcium, magnesium, iron...
Plants use various mineral elements to develop.
In a traditional vegetable garden, some of these elements are available in the soil. In hydroponics, they are provided in the water in a form accessible to the roots. Penn State lists 17 nutrients considered essential to the functioning and development of plants.
🌡️ A suitable environment
Temperature, light, humidity, available space, root oxygenation, and nutrient concentration influence growth.
That is where a large part of the appeal of hydroponics lies: better control of some of these parameters.
How does a hydroponic garden work?
There are several techniques for hydroponics, but the general principle remains similar.
1. You germinate a seed
The seed is generally placed in a small sponge or other growing medium.
This medium does not necessarily nourish the plant. It serves primarily to maintain humidity around the seed and to support the development of the first roots.
2. The roots access water and nutrients
Once developed, the roots come into contact with a nutrient solution.
It is this solution that replaces part of the role usually played by the soil.
3. Water can be circulated
In many domestic systems, a small pump is used to periodically circulate the water.
However, not all hydroponic systems work in the same way: some use circulating water, others keep the roots in an aerated solution, and still others use different substrates.
4. The plant receives enough light
Outdoors or in a greenhouse, this light can come from the sun.
Indoors, some hydroponic gardens directly integrate a horticultural lamp, which means you don't have to rely entirely on the exposure of a window.
Artificial light also allows for certain crops to be continued when natural light becomes insufficient.
5. The plant grows... then comes the harvest
When water, light, nutrients, and the environment are suitable, the plant can devote its energy to growth.
It obviously remains to observe, maintain, and finally harvest.
Hydroponics does not eliminate gardening. It seeks instead to make some of its parameters easier to control.
What are the different types of hydroponics?
You will likely encounter several terms when you start learning about it.
No need to master them all to get started.
Among the most common systems, we find:
Deep Water Culture (DWC)
The roots develop directly in a nutrient solution, usually oxygenated.
NFT — Nutrient Film Technique
A thin layer of nutrient solution circulates continuously or regularly along the roots.
Irrigation or water circulation systems
A pump moves the nutrient solution between a reservoir and the roots.
Substrate cultivation
The soil is replaced by a material such as coconut fiber, rock wool, or certain aggregates, while the nutrients are provided with the water.
Therefore, there is not just one hydroponics, but several ways to apply the same principle.
Why is hydroponics interesting in an apartment?
This is probably one of its most interesting uses.
With traditional gardening, several constraints appear quickly when you live in the city:
no garden, little space, imperfect exposure, soil to store and handle, watering sometimes forgotten...
A compact hydroponic garden helps to change this equation.
A little space can be enough
Some systems are compact enough to be installed on a countertop, a shelf, or a small piece of furniture.
It thus becomes possible to grow a few edible plants closest to the place where they will be used.
No soil to handle
No bags of potting soil to store in the apartment and no soil spilled around the pots.
Watering becomes different
In a system with a reservoir, you no longer need to water each plant individually with a watering can.
You still need to monitor and top up the water when necessary, but the operation is different from a collection of traditional pots.
Light can be better controlled
This is one of the main advantages of models equipped with a horticultural light: the success of the crop depends less on a perfectly exposed window.
What can be grown with hydroponics?
Many more things than one might think.
But not all plants are as easy to grow.
🌿 Herbs
Basil, parsley, and many other herbs are very good crops to start with.
They take up relatively little space and are particularly interesting to harvest as needed in the kitchen.
🥬 Lettuce and leafy greens
Lettuces and microgreens are also very well suited to many hydroponic systems.
🍓 Strawberries
They can grow in hydroponics, but require more attention than some herbs.
🍅 Tomatoes
Tomatoes can also be grown without soil.
However, one must take into account their size, their light requirements, and, indoors, pollination.
🌶️ Peppers and chili peppers
They are also possible but generally require more time and space than a lettuce or basil.
For a first crop, it is therefore better to start simply rather than trying to fill all the spots with the most ambitious crops possible.
What are the advantages of hydroponics?
The point is not to claim that this method is superior to all others.
Soil gardening works very well.
Hydroponics simply responds particularly well to certain uses.
It allows for growing without a garden
This is its most obvious advantage for many people.
It offers more control
The gardener can better control the supply of certain nutrients, water, and, with an equipped system, lighting.
The control of water and nutrients around the roots is precisely among the interests identified by the Royal Horticultural Society.
It is suitable for small spaces
You can concentrate several crops in a relatively limited space.
It allows for growing without soil
An advantage particularly appreciated indoors.
It brings growing closer to everyday life
A few basil leaves for pasta?
A salad to harvest?
The idea is simply to be able to cut what you need directly at home.
And what are its limits?
They exist, and it is better to know them before starting.
You still have to take care of your plants
A hydroponic system does not turn a plant into an autonomous object.
You still must:
- check the water level;
- provide nutrients correctly;
- clean the system;
- observe the plants;
- prune certain crops;
- sometimes help with pollination;
- intervene when a plant presents a problem.
Nutrients must be correctly dosed
More is not synonymous with better.
A solution that is too concentrated can be just as problematic as a solution that is not nutritious enough. Penn State also reminds us that hydroponic systems can react quickly to nutritional imbalances.
pH can be important
pH influences the availability of certain nutrients for the plant.
This is a subject we will cover separately on the blog, as it deserves its own guide.
Not all plants are grown in the same way
A lettuce and a tomato plant obviously have neither the same size nor the same needs.
The choice of crops remains important.
Hydroponics or soil cultivation: which to choose?
There is no universal answer.
Choose soil cultivation if you enjoy gardening traditionally, have enough space, and wish to grow a very wide variety of plants.
Hydroponics becomes particularly interesting if you lack space, wish to grow indoors, or want to better control your plants' environment.
The two methods are not incompatible, for that matter.
You can perfectly well have a few plants in soil on a balcony and a small hydroponic garden in your kitchen.
The best gardening remains that which fits your daily life.
How to get started with hydroponics at home?
No need to start with a complex installation.
Step 1 — Choose an easy crop
For a first experience, start with an herb or a lettuce.
You will understand the system's operation much more easily.
Step 2 — Choose a system adapted to your space
Ask yourself a few very simple questions: