By the AtmoSerre team
Hydroponics, or soilless plant cultivation, involves growing fruits, vegetables, and ornamental plants directly in an aqueous nutrient solution. This soilless approach is accessible to both amateurs and professionals and allows for precise control of plant nutrition, promoting rapid growth and optimal yield. Discover our tips for choosing the right system, monitoring key parameters, and making the most of your hydroponic or bioponic crops.
Article Summary
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What is hydroponic cultivation?
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The rise of soilless cultivation
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Advantages and limitations of hydroponics
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Essential parameters: nutrients, oxygen, pH
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Different hydroponic systems
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Bioponics and aquaponics
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FAQ: common questions about hydroponics
What is hydroponic cultivation?
Hydroponics is still little known to the general public, but it is the main production method for many modern fruits and vegetables. Tomatoes, strawberries, and salads sold in supermarkets mostly come from hydroponic systems, sometimes up to 90% for tomatoes grown in commercial greenhouses.
Unlike soil cultivation, soilless plants draw their nutrients directly from water enriched with essential minerals. The key element of this technique is therefore the nutrient solution, which must be correctly dosed to ensure healthy root development and abundant production.
Components of a hydroponic system
A complete hydroponic system generally includes:
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Growing trays: from simple shallow trays to sophisticated multi-level installations.
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Substrate: neutral, draining, and sterile, such as clay pebbles, perlite, or coconut fiber, to support plants and allow root aeration.
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Supports or baskets: perforated to ensure optimal drainage and prevent water stagnation.
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Oxygenation system: to maintain a sufficient dissolved oxygen level in the water.
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Nutrient solution: water enriched with essential minerals in ionic form, directly assimilable by plants.
Additional equipment that may be included:
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Pumps for water circulation
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Ventilation to regulate temperature
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Water chillers to prevent overheating
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Artificial lighting to extend the photoperiod
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pH, electrical conductivity, and temperature probes
These elements make it possible to reproduce optimal conditions for soilless growth and obtain vigorous plants, even in urban or infertile environments.
Hydroponics, a rapidly expanding cultivation method
Hydroponic cultivation is experiencing spectacular growth, as it addresses modern challenges: population density, water scarcity, and soil pollution. While large high-tech greenhouses and urban micro-farm startups attract attention, this technique is actually very ancient. Civilizations like the Aztecs already cultivated on floating structures called chinampas, and some hydroponic practices still persist worldwide.
Surprisingly: hydroponics could one day support space exploration. NASA is already testing hydroponic systems aboard the International Space Station, and projects for soilless cultivation on Mars are being studied.
Controversies and misconceptions
A “unnatural” cultivation method?
Some consider soilless cultivation to be unnatural. In reality, bioponics strives to be more environmentally friendly, using organic minerals and drawing inspiration from permaculture.
Tasteless vegetables?
The taste of vegetables depends mainly on the variety and ripeness stage, rather than the cultivation method. Hydroponic tomatoes can compete with those grown in open soil, and many Michelin-starred chefs even exclusively use soilless products for their taste quality and consistency.
Advantages and limitations of hydroponics
Strengths
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Water savings: hydroponic cultivation uses up to 10 times less water than traditional soil cultivation. Example: producing 1 kg of tomatoes requires 214 L of water in conventional agriculture, compared to only 20 L in hydroponics.
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Cultivable on polluted soils: ideal for land contaminated by pesticides or heavy metals.
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Space saving: vertical farming optimizes surfaces, especially in urban areas.
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Rapid growth and high yield: optimal nutrient supply accelerates plant development.
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Fewer diseases and chemical inputs: soilless roots are less exposed to pathogens.
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Reduction of weeds: the sterile substrate prevents the development of weeds.
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Clean, ready-to-eat vegetables: no more need to clean soil from roots.
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Ergonomics and simplified maintenance: working on raised trays reduces physical effort.
Limitations
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Initial investment: trays, pumps, lighting, and nutrients represent a significant cost.
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Dependence on nutrient solutions: plants are entirely dependent on supplied inputs.
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Ecological balance debated: plastic, energy, and equipment can reduce the positive environmental impact.
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Continuous monitoring: it is essential to regularly check the pH, oxygenation, and conductivity of the nutrient solution.
Essential parameters to monitor
1) Oxygenation: the key factor in hydroponic cultivation
In hydroponic cultivation, the dissolved oxygen (DO) level is the most important parameter for root health. Without sufficient oxygen, they cannot breathe properly or absorb nutrients, even if the nutrient solution is well-dosed.
Good oxygenation allows for:
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White and vigorous roots
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Better nutrient absorption
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Rapid and uniform growth
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Fewer root diseases
Conversely, stagnant water poor in oxygen can quickly lead to root asphyxiation.
⚠️ Symptoms of oxygen deficiency
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Roots rising to the surface
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Yellowing or wilting leaves
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General loss of vigor
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Appearance of root rot (brown and soft roots)
How to properly oxygenate your system?
The equipment is simple and similar to that of an aquarium:
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Air pump
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Hose
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Air stone
The air stone diffuses fine bubbles that increase oxygen dissolution in the water.
🎯 Ideal rate: between 7 and 10 ppm at room temperature (compared to 5 to 7 ppm for tap water).
A dissolved oxygen probe allows for precise control.
Factors that reduce oxygenation
🌡 Water Temperature
The warmer the water, the less oxygen it retains.
👉 Ideally, the nutrient solution should remain between 18 and 20°C.
Beyond that:
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DO decreases
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Harmful bacteria develop more easily
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The risk of rot increases
🧂 Salinity and excess nutrients
A high salt concentration (high EC) reduces the water's capacity to hold oxygen.
It is therefore recommended to:
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Avoid nutrient overdose
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Use low-mineral water
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Regularly monitor electrical conductivity (EC)
Professionals often use reverse osmosis water to precisely control mineral composition.
In hydroponics, roots depend entirely on dissolved oxygen, unlike soil cultivation which naturally contains air pockets.
This is why oxygenation remains the true pillar of a high-performance hydroponic setup.
2. Nutrient supply (nutrient solution)
In hydroponic cultivation, plants grow without soil: all their nutrients must therefore be supplied directly in the water. Tap water is not enough; it is essential to add a suitable nutrient solution to it.
Needs vary depending on the plant and, above all, its growth stage (growth, flowering, fruiting). To avoid dosage errors, ready-to-use solutions are available, simple and safe for beginners.
Essential nutrients
Plants need about fifteen minerals divided into two categories:
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Macronutrients (in large quantities): nitrogen, phosphorus, potassium, calcium, magnesium, sulfur...
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Micronutrients (trace elements): iron, zinc, boron, copper, manganese, molybdenum...
Electrical conductivity (EC): the key to correct dosage
In hydroponics, nutrients are absorbed as ions dissolved in water. Their concentration is measured by electrical conductivity (EC).
Too low EC = deficiency.
Too high EC = nutrient excess, which can block absorption and stress the plant.
Monitoring EC therefore ensures a perfectly balanced supply and optimizes growth. 🌱
3) pH: a crucial balance in hydroponics
In hydroponics, water pH plays a crucial role. It is measured on a scale of 1 to 14:
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pH < 7: acidic medium
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pH = 7: neutral
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pH > 7: basic
Each plant has an ideal pH range. If this level is not respected, the roots will have difficulty absorbing minerals, even if the nutrient solution is perfectly dosed.
Why is pH more sensitive in soilless cultivation?
In open ground, the soil acts as a buffer effect: it naturally stabilizes pH variations.
In hydroponics, there is no such protection. The slightest imbalance can quickly disrupt growth.
It is therefore essential to regularly monitor the pH using test strips or an electronic tester.
Substrates already buffered
Certain substrates used in hydroponic cultivation, such as clay pebbles, are generally pre-buffered. This means that their pH has been stabilized upstream to avoid any imbalance from the start of cultivation.
A controlled pH means optimal nutrient assimilation... and healthy plants 🌱
The different hydroponic systems
There are several hydroponic systems for supplying water and nutrients to plants. Some are very simple, others more technical, but all are based on the same principle: nourishing the roots directly via a nutrient solution.
We generally distinguish between passive systems (without pump) and active systems (with water circulation or oxygenation).
🌱 Passive Systems
Kratky System
The simplest to set up. Plants are installed in baskets above a tray filled with nutrient solution. The roots partially soak in the water, allowing them to feed while remaining oxygenated. Ideal for beginners.
Wick system
Similar to Kratky, but water rises to the roots by capillarity thanks to a wick. Irrigation is gentle and continuous. However, it is necessary to ensure that the wicks remain well hydrated.
💧 Active Systems
DWC (Deep Water Culture)
Active variant of Kratky. The roots are completely submerged in the nutrient solution. The water must be continuously oxygenated with an air stone to prevent root asphyxiation.
Ebb and flow system (ebb and flow table)
The roots are regularly flooded then drained (ebb and flow). This alternation allows for good oxygenation while ensuring an efficient nutrient supply.
Drip system
Each plant receives the nutrient solution via drippers, just like in soil. The system operates in a closed circuit with a reservoir.
NFT (Nutrient Film Technique)
Plants rest on a slightly inclined support. A thin film of water continuously circulates along the roots before returning to the reservoir. Very efficient and water-saving.
Aeroponics
The roots are suspended in the air and regularly sprayed with a fine nutrient mist. Oxygenation is maximal, which promotes rapid growth.
Aero-hydroponics
Combines deep water culture (DWC) and aeroponic spraying. Plants benefit from both abundant irrigation and excellent oxygenation.
Bioponics and aquaponics
🌿 Bioponics: a more natural hydroponics
Bioponics is an ecological variant of hydroponics. The main difference? The nutrients are no longer of chemical or mineral origin, but come from organic matter.
Please note: bioponics is not "organic" cultivation in the regulatory sense. Hydroponics cannot obtain the organic label, which is reserved for soil cultivation. Here, only the origin of the minerals changes.
The inputs can come from:
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plant manure
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compost tea
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worm castings
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any organic matter rich in nitrogen (N), phosphorus (P), and potassium (K)
However, these elements are not immediately assimilable. They must first be mineralized by bacteria, which transform them into ions assimilable by the roots.
🔬 The key role of the biofilter
The biofilter is the heart of the bioponic system.
It houses bacterial colonies responsible for transforming organic matter into bioavailable minerals, while preventing waste from coming into direct contact with the roots.
Concretely, it is a compartment filled with porous materials promoting microbial development. Inoculation occurs naturally via ambient air, but it is common to add Trichodermas, symbiotic fungi that improve nutrient absorption and stimulate growth.
🐟 Aquaponics: the balance between plants and fish
Aquaponics combines bioponics and fish farming in a circular system.
The fish waste, rich in nitrogen, phosphorus, and potassium, serves as a nutrient base. Nitrifying bacteria then transform them into elements assimilable by the plants.
Species such as trout, tilapia, or salmon can be used depending on the system configuration.
The principle is based on a virtuous cycle:
fish → organic waste → bacteria → nutrients → plants → filtered water → fish
In practice, the balance is delicate:
it is necessary to adjust the number of fish, monitor sanitary risks, and maintain a stable nutrient production.
When well controlled, aquaponics allows the creation of a self-sufficient ecosystem that is productive and particularly sustainable. 🌱🐟
Frequently asked questions
What varieties can be grown hydroponically?
Hydroponic cultivation is suitable for almost all varieties: fruits, vegetables, flowers, and even some trees can grow without soil.
The easiest to cultivate are generally:
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leafy greens (lettuce, spinach, arugula...)
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aromatic herbs (basil, mint, cilantro)
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certain flowers, such as orchids
These plants require little structural support and offer quick results.
On the other hand, tall or voluminous varieties like tomatoes, peppers, or cucumbers are more delicate. They require adapted staking, which can sometimes be more complex to set up in soilless cultivation.
Can urine be used in hydroponics?
Yes, it is possible. Urine is naturally rich in nitrogen, a key element for plant growth. This practice is sometimes called "peeponics", derived from the term anthroponics, which refers to human-derived nutrients.
However, several precautions are necessary:
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legislation strictly regulates this practice
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crops must be intended for personal use
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there is a risk of unpleasant odors
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certain medications (antibiotics in particular) can contaminate the nutrient solution
This type of approach therefore remains marginal and requires particular vigilance.
Does hydroponics use a lot of water?
No, on the contrary. Hydroponic cultivation operates in a closed circuit, which allows water to be recycled continuously.
Consumption can be up to 80 to 90% lower than that of open-field cultivation. Unabsorbed water by the roots returns to the reservoir and is reused, thus limiting waste.
Can hydroponics be done indoors?
Yes, it's even one of its great advantages. Hydroponics is perfectly suited for indoor cultivation, under artificial lighting (horticultural LEDs).
This allows for:
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cultivating all year round
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controlling temperature and humidity
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producing in small spaces (apartment, garage, urban greenhouse)
With good control of light, pH, and the nutrient solution, high yields can be achieved, even in a small area. 🌱
Conclusion
Hydroponics is no longer just an experimental alternative: it is now a high-performance, precise cultivation method adapted to modern challenges.
By eliminating soil, you gain in control, yield, and water saving. Whether you opt for a simple system like Kratky, a more technical DWC setup, or even a sustainable approach with bioponics or aquaponics, the principle remains the same: control oxygenation, the nutrient solution, and pH to provide your plants with optimal conditions.
When properly executed, hydroponic cultivation allows for:
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Faster growth
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Abundant harvests
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Year-round production
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More rational use of resources
Accessible to beginners and demanding enthusiasts alike, it adapts as well to an urban balcony as to a professional greenhouse.
🌱 Ready to take action?
Our greenhouses offer the ideal environment to set up your hydroponic cultivation under perfectly controlled conditions: stable temperature, protection from bad weather, and optimized growth all year round.
Discover our collection of garden greenhouses and create the perfect space to develop your hydroponic setup, from simple beginner systems to the most ambitious configurations.
With AtmoSerre, give your crops the environment they deserve!