hydroponics
Hydroponics: The Ultimate Guide to Soilless Growing for Producing Food at Home
Discover hydroponics: grow fresh vegetables at home without soil. Systems, yields, real budgets, beginner tips and French rules — the ultimate guide.
Claire lost her tomatoes this summer.
A south-facing balcony in Lyon. Three plants pampered since April, watered every evening, almost talked to. The result: blight, soil that cracked at the first heatwave, and a harvest that fit in a salad bowl. As she filled her watering can, she asked herself the question you may be asking too: why so much water for so little?
The answer comes down to one number: producing 1 kg of tomatoes takes 13 to 14 liters of water in a hydroponic greenhouse, versus more than 200 liters in open-ground soil — that’s the figure that sums it all up (Wikipedia, bibliographic sources cited).
Fifteen times less water.
Hydroponics in a nutshell: plants grown without soil, their roots housed in an inert growing medium (clay pebbles, rockwool, coco coir) or bathed directly in water enriched with mineral salts. And your first working system can be set up at home for under €200.
Under €200. Reservoir, air pump, growing medium, plants included.
All that remains is to know how, with which plants, for what budget, and under which rules — that’s what this guide lays out without sugarcoating: principles, systems (NFT, DWC, vertical towers), forgiving varieties, real budgets, French regulations, and the questions every beginner asks, with their answers. If Claire reminds you of someone, you’re in the right place.
Editorial method for this guide. Scientific publications and official sources come first (Persée, 2023 scientific review, Légifrance, service-public.fr). On budgets and yields, no recent French public statistics exist: this guide therefore draws on specialized guides published in 2026, and this is flagged every time. No figure is presented as certain without a source.
Table of Contents
- What is hydroponics? Definition and principles
- The different hydroponic systems
- Yields and performance of hydroponics
- Which plants to grow in hydroponics?
- How to get started with hydroponics at home
- Hydroponics in a greenhouse: the winning combination
- Budget and profitability of a hydroponic setup
- FAQ — Your questions about hydroponics
- Conclusion — Move on to production with hydroponics
What is hydroponics? Definition and principles
The definition, straight up
Hydroponics: from the Greek hydôr (water) and ponos (labor). Water that works in place of soil, literally. Growing plants without soil, in short.
Concretely, the roots spread through a neutral, inert growing medium — sand, pumice, clay pebbles, rockwool, perlite — regularly irrigated with a water solution loaded with mineral salts and trace elements (Wikipedia ; Futura-Sciences).
The soil hasn’t magically disappeared: it has simply been replaced. The medium provides no nutrients; it holds the plant up. The entire nutritional function rests on the enriched water. Soilless growing, soilless culture, hydroponics — three ways of saying the same thing.
One nuance that matters when reading statistics: the scientific literature distinguishes pure solution culture, where the roots dip directly into the water (forcing endives remains the oldest example), from granular substrate culture with irrigation (PMC, 2023). In everyday language, “hydroponics” covers both without distinction — and for home use, that’s probably just fine.
What a plant actually needs
A plant asks for five things: light, an appropriate temperature, sufficient humidity, oxygen at the root level, and a supply of water, mineral salts and trace elements (Wikipedia).
In open ground, the soil acts as a nutrient reservoir. Except it rarely contains all the elements in the right proportions. You then depend on a medium whose composition, depth and season you don’t control — Claire’s painful lesson, in short.
Hydroponics flips that logic. Every parameter becomes adjustable: the composition of the solution, its acidity (pH is generally set between 5.5 and 6.5 for vegetables and flowers, Wikipedia), root oxygenation, temperature. The solution often circulates in a closed loop and is recycled, hence the spectacular water savings.
These foundations aren’t new. They go back to the work of the German botanists Julius von Sachs and Wilhelm Knop, in 1860 (IJPSS, 2023). And France, as you’re about to see, wrote some of the least-known pages of that history.
A brief history and its rise in France
The French history of the discipline is surprisingly deep. As early as 1898–1919, Émile Mazé was working at the Institut Pasteur on the mineral nutrition of maize in nutrient solution; in 1924, Georges Truffaut carried out his first water cultures under aseptic conditions (Persée, 1998).
In the 1930s, the American Gericke popularized the technique worldwide, and the French horticultural press went wild: yields of 551 to 927 tonnes of tomatoes per hectare were announced.
Never validated.
Promotional figures of the era, cited here only as evidence of the enthusiasm of the moment (Persée, 1998). Keep that anecdote in mind: if a website is selling you astronomical yields today, you’ll know exactly where its argument comes from.
The serious trials came later. In 1938, Truffaut and Hampe tested fifteen vegetable species and thirteen flower species at Versailles, with public demonstrations at the Société nationale d’horticulture. After the war, INRA ran systematic experiments at Cap d’Antibes from 1947 onward. Then the rose breeder Meilland developed, in 1950, a recycled sub-irrigation system in sand trenches — to escape the whims of the soil, densify plantings and reduce labor (Persée, 1998). A pioneering use case, at the scale of an actual farm, long before the word “hydroponics” entered everyday vocabulary.
The growth became measurable. At the 1996 census (ONIFLHOR), France had more than 1,200 ha of soilless crops on inert substrates, dominated by tomatoes (80%), i.e. 20% of the world’s soilless vegetable area at the time, versus 50% for the Netherlands (Persée, 1998). Full transparency: these data are several decades old, and no more recent official French statistic could be confirmed to date.
You now know where this technique comes from — and which figures deserve your trust. All that’s left is the decision that drives everything else: choosing your system.
The different hydroponic systems
All these systems do the same thing — deliver water, nutrients and oxygen to the roots — but each does it its own way. Here are the four families that matter, from simplest to most technical. And you’ll soon understand why the best choice for beginners is almost never the most impressive one.
The NFT system (Nutrient Film Technique)
NFT rests on a clever physical insight: stagnant water aerates very poorly. So the solution circulates as a thin film along the bottom of slightly sloped channels, under the roots; as it flows, it picks up oxygen, returns to the reservoir, and loops back in a closed circuit (Wikipedia).
This system excels with fast crops: lettuces, basil, strawberries, culinary herbs. Hence its presence in so many professional farms. The trade-off fits in one sentence — everything rests on a pump and a constant flow rate. A few hours without power, and the roots dry out. In France, it was marginally used for tomatoes, about 50 ha in Brittany in the 1990s (Persée, 1998).
A brilliant system in a professional greenhouse, vulnerable to a simple power cut: keep that fragility in mind, it will weigh on your choice.
The DWC system (Deep Water Culture)
DWC does exactly the opposite: the roots sit permanently in a reservoir of nutrient solution, kept oxygenated by an air pump — the principle of an aquarium, in short (2025 review). The plants sit in mesh baskets (net pots) filled with clay pebbles.
It’s the choice most often recommended for beginners: “simple and economical,” according to Loisir-Jardin, ideal for 1 to 3 plants. A living-room DWC amounts to very little, in fact: an opaque 30–60 liter bin, two or three baskets, an air pump, one lettuce per basket.
Its passive variant, Kratky, doesn’t even need a pump or electricity — an opaque container, a plant, an air gap between the liquid and the basket, and the growing begins. Hard to do simpler for a first try.
Vertical hydroponic towers
The hydroponic tower stacks growing sites vertically: the solution is pumped to the top, trickles down along the roots, then flows back to the reservoir. Most operate on the nutrient film principle — a vertical variant of NFT, in a way.
Their decisive advantage is measured in floor space: a tower of less than one square meter can carry dozens of plants. Lettuces, strawberries and herbs thrive in them, and urban micro-farms have made them their standard (bsness.fr, 2026).
To be precise: manufacturers are quick to highlight this densification, but no quantified multiplication factor, validated by an official source, is publicly available. Take it for what it is.
Drip systems and substrate growing
Here, plants grow in an inert substrate (coco coir, clay pebbles) irrigated by drippers connected to the reservoir. Its close cousin, Ebb & Flow (flood and drain), periodically floods a growing table before draining it (Habitats Durables, 2026).
These systems handle heavy, hungry plants — tomatoes, cucumbers, peppers — and scale up to professional use. Coco coir, moreover, offers the gentlest transition from traditional soil growing (HydroParadise, 2026).
Aeroponics, which mists suspended roots, pushes the logic to the extreme: maximum yield, high maintenance, zero tolerance for failure — roots dry within minutes. The idea is attractive on paper. In practice, it belongs to the expert tier.
Comparison table of systems
| System | Difficulty | Ideal plants | Indicative budget* | For whom? |
|---|---|---|---|---|
| Kratky (passive container) | Very easy | Lettuces, herbs | €25–50 (DIY) | The curious, first try |
| DWC | Easy | Lettuces, basil, herbs | €80–400 | Beginners (1 to 3 plants) |
| NFT | Intermediate | Lettuces, strawberries, herbs | €200–700 | Intermediate |
| Vertical tower | Intermediate | Lettuces, strawberries, herbs | Varies by capacity | Small spaces, greenhouses |
| Drip / Ebb & Flow | Advanced to pro | Tomatoes, cucumbers, peppers | €1,500–5,000 | Intensive production |
| Aeroponics | Expert | Tomatoes, peppers, seedlings | €500–2,000 | Advanced users, experimentation |
* Ranges drawn from 2026 commercial guides (Amperel, HydroParadise, Plante Hydroculture) ; what’s included differs from one source to another (system alone, or with lighting and ventilation). Treat them as market orders of magnitude, not official prices — the sites publishing them often have kits to sell, which is worth knowing.
The choice is rarely made on technology alone. A stable DWC outproduces a temperamental NFT: start where your daily life gives you the best odds of success, then move up. There’s no rush.
But a system, however well chosen, doesn’t produce magic. The real question, the one that decides everything: how much does it actually yield? The numbers will surprise you — and some will disappoint you.
Yields and performance of hydroponics
Production in kg/m²/year: the real numbers
Take ten seconds to picture the scene. A Sunday in February, rain outside. At home, under the LED bar, tomato no. 3 is already carrying seven fruits. That’s the image behind the question — and the answer deserves your full clarity.
Let’s be honest: consolidated yield figures are scarce, and this is the most delicate point of the whole topic. Here’s what’s most solid out there.
Professional references commonly associate hydroponic greenhouse tomatoes in France with yields on the order of 50 to 60 kg/m²/year, and NFT lettuce with 8 to 12 cycles per year. These orders of magnitude come from the sector’s technical literature — no recent official French publication (INRAE, FranceAgriMer, INSEE) consolidates them publicly. For any serious sizing, have them confirmed by the CTIFL, the interprofessional technical center for fruits and vegetables.
⚠️ The trap of spectacular figures. The vertiginous yields circulating online often trace back to Gericke’s promotional demonstrations (1938). Those are claims of their era, never validated. Only one performance figure is truly well documented in the sources: that of water, just below.
Comparison with open-ground growing
| Criterion | Hydroponics | Open ground |
|---|---|---|
| Water per 1 kg of tomatoes | 13–14 L (greenhouse) | More than 200 L |
| Weeds | Almost none | Regular weeding |
| Season | Year-round indoors | Depends on climate |
| Pesticides | Reduced (controlled environment) | Treatments often needed |
| Energy | Electricity (pumps, lighting) | Almost none |
| Material dependence | High (a failure = quick risk) | Low |
Sources: Wikipedia for the water ratio ; Semences du Jardin and Croquepousse for practical strengths and limits.
The water ratio — roughly fifteen times less — remains the best-supported figure in the file. Guides even mention “up to 90% savings” in closed-loop systems; an editorial maximum, not a measured average. But energy is the real counterweight in the equation, and it mustn’t be forgotten: without renewables, the carbon footprint of an indoor system can turn out less favorable than local outdoor growing (Croquepousse).
In other words, hydroponics doesn’t win on every front. It wins on the ones that matter most when you grow at home: water, season, cleanliness of the environment. And those victories don’t fall from the sky — they’re built.
The factors that make productivity vary
Yield per square meter depends on parameters you control — good news, right? Light first: 12 to 16 hours a day for leafy greens, with a mandatory dark period (Semences du Jardin). Then temperature: optimal between 18 and 24 °C for leafy crops, 22 to 26 °C for tomatoes and peppers, with a target humidity of 60–75%. Above 85%, fungal diseases start lurking (Aquaponie-maison, 2026).
Add to that the type of system, staking for climbing crops — a staked cucumber is “very productive” — vigilance over calcium and magnesium deficiencies in fruiting vegetables, and above all consistency of monitoring. Productivity isn’t a lottery. It’s a sum of small, constant gestures, repeated week after week.
Still, those gestures need to be entrusted to the right plants. And that strategic choice differs from what garden-center shelves suggest.
Which plants to grow in hydroponics?
Which vegetable should you grow in hydroponics as a beginner? The golden rule of specialized guides fits in one sentence: leafy greens and herbs first, fruiting vegetables next, strawberries once you’ve mastered conductivity (Permacademy).
Already dreaming of cherry tomatoes and strawberries? Hold your enthusiasm a little. Your first success sets the tone for all the others — and it rarely happens with a fruiting vegetable.
The easiest vegetables for beginners
“Lettuce is often considered the best plant for starting out in hydroponics, and not by chance. Easy to grow, undemanding and very tolerant of small mistakes, it quickly lets you confirm that the system is working properly” (Permacademy). According to the same guide, its quick harvest is “very rewarding”: it’s often at that precise moment that a beginner gets hooked for good. No surprise there.
| Plant | Level | What to know |
|---|---|---|
| Lettuce | Very easy | Fast, tolerant, the go-to starter crop |
| Basil | Easy | Continuous harvest through successive cuttings |
| Cilantro | Easy | Quick, but bolts if it gets too hot |
| Bok choy | Easy | 35 to 60 days depending on the cultivar |
| Arugula | Easy | Very fast growth, instant gratification |
| Spinach | Medium | Likes it cool, sensitive to heat |
The same families come up under greenhouses: “lettuces, batavia lettuce, arugula, mizuna, basil, mint, cilantro, parsley, chives,” chosen for their “fast cycles” and tolerance of moderate temperature variations (Habitats Durables, 2026). On this point, all the sources consulted agree. No disagreement to report.
High-yield plants
You have the ceiling height, a few successful cycles behind you and an appetite for big harvests? Then the productivity champions await: fruiting vegetables. Cherry tomatoes combine a “long cycle, but high yield,” provided you give them full sun or powerful LEDs; cucumbers are “very productive if staked”; peppers “require patience, but are stable” (Permacademy).
In return, these plants demand enough height for trellising (strings, stakes, wires), richer feeding, attention to calcium and magnesium deficiencies, and good ventilation (Habitats Durables, 2026). Suitable systems: drip, Ebb & Flow, aeroponics. One honest precision, once again: no source quantifies these yields in kg per plant. The descriptions remain qualitative.
Advanced species for experts
The strawberry is the archetypal advanced species: “a somewhat more advanced level” (Néphalie), requiring fine control of the solution’s electrical conductivity (EC) — “super satisfying, watch the EC,” sums up Permacademy. Aeroponics is the other expert tier: maximum yield, but high maintenance (HydroParadise, 2026).
The recommended progression stays crystal clear: rack up successes on short cycles, understand “the rhythm of hydroponics,” then step up in difficulty. No need to rush; lettuces already teach plenty.
The plan is taking shape: a simple system, forgiving plants, a controlled budget. All that’s missing is the day-one how-to — and the list of traps every beginner runs into. It’s shorter than you think.
How to get started with hydroponics at home
The essential equipment to begin
Remember Claire: she watered without ever knowing. Hydroponics replaces blind guessing with measurement — provided you gather six pieces of equipment (Plante Hydroculture), each answering a specific problem.
The reservoir first: a bucket, a bin, a container, strictly opaque, because light combined with water and nutrients triggers algae growth, which quickly suffocates the roots. Next, oxygenation: an air pump with an air stone, plus a check valve that keeps the solution from flowing back into the pump when it’s off. Then come the net pots, whose mesh lets the roots through, and the inert growing medium — clay pebbles, rockwool or coco coir.
What remain are the two items that determine success. The pH/EC meter, to check acidity and nutrient concentration: “prioritize the quality of your testers over premium lighting at the start,” advises Amperel, 2026 — the most useful hands-on advice in the whole corpus. Measuring accurately beats lighting expensively. And the specific nutrients: budget 10 to 15 € for the first month.
LED lighting (15 to 50 €) remains optional at the very beginning if you have a bright window. As for volumes, plan for 8 to 12 liters of solution per plant in the vegetative phase, then 12 to 20 liters (HydroParadise, 2026).
Starting budget by ambition level
Looking for a cheap hydroponic system? The DIY route is very real: a DWC in a recycled container comes to €25–50 excluding lighting, versus €60–150 for an equivalent commercial kit (Plante Hydroculture). Each tier then has its market range:
| Profile | Recommended system | Indicative budget* |
|---|---|---|
| DIY discovery (3–6 plants) | Kratky or homemade DWC | €25–50 |
| Equipped beginner | DWC or kit | €80–400 |
| Intermediate (4–12 plants) | NFT or RDWC | €200–800 |
| Advanced | Aeroponics | €500–2,000 |
| Intensive production | Drip | €1,500–5,000 |
* 2026 market data, varying scopes depending on the source (see note on the comparison table). A complete entry-level setup — DWC, entry-level LED, fertilizer, meters — sits between 400 and 600 € for 2 to 4 plants in a tent (HydroParadise) ; “a basic system for 3-4 plants starts around 150-200 €” (Amperel).
And the most solid strategic advice in the corpus comes from Habitats Durables: “for a start, limit the number of simultaneous technologies. Set up a single type of system, stabilize it, then add other modules later.” One stable system beats two struggling systems. That holds for gardening. It holds everywhere else.
Beginner mistakes to absolutely avoid
These traps have already buried thousands of promising projects. All are known, all are avoidable — here they are, unfiltered.
The transparent reservoir, first. Light, water, nutrients: algae move in and quickly suffocate the roots (Croquepousse). Opaque. Always.
The absence of measurement, next. Check pH and EC at least once a week. White roots signal a healthy plant; a drifting solution, no.
Multiplying systems right away. One technology at a time, stabilized, before expanding. It’s the same principle as any workshop that works.
The forgotten observation schedule. Water level, root color, pump, algae: a glance every day or two is enough (Semences du Jardin).
The neglected dark period. Plants need at least 8 hours of night, even under LEDs.
A small solution in a warm reservoir. It loses balance fast (Semences du Jardin).
Immediate tomatoes, finally. Fruiting vegetables forgive less than lettuce. Earn your first stripes on leafy greens.
Seven mistakes, seven habits to adopt instead. On paper, your setup holds up. All it’s missing is a roof — and you’re about to see why the greenhouse changes everything.
Hydroponics in a greenhouse: the winning combination
Why the greenhouse changes everything
The greenhouse acts as a “climatic and sanitary barrier around the hydroponic system”: it “limits sudden temperature swings, protects from wind and rain, and reduces pressure from certain pests” (Habitats Durables, 2026). You then combine two registers: the greenhouse’s natural light and extended season, plus hydroponics’ control over water and nutrients.
And the space needed often surprises. “A home hydroponic greenhouse doesn’t necessarily require a large area: a 4 to 6 m² shelter already allows a compact system of lettuces, herbs and a few tomatoes.” The same guide recommends starting on a limited area, then expanding — the expense is spread over several seasons, which is nothing to sneeze at.
The concrete case: 22 m² of greenhouse = 500 kg/year
That’s the dream scenario. So, credit of 500 kg per year in a 22 m² greenhouse? Let’s do the math transparently, because no official statistic validates that figure.
500 kg over 22 m² is about 23 kg per square meter per year, aisles included.
23 kg. Per m². Per year.
Now, professional references cite 50 to 60 kg/m²/year for hydroponic greenhouse tomatoes (order of magnitude to confirm with the CTIFL). The target therefore sits roughly halfway to the professional standard: ambitious for an amateur, not unrealistic. To get close, four boxes must be ticked.
Heavy crops in rows, on half the surface: cherry tomatoes, trellised cucumbers. Fast, continuous cycles on the rest — lettuces every month, permanent herbs. Vertical towers along the walls, to stack production without consuming floor space. A controlled climate, finally: supplemental heating in winter, ventilation in summer, supplemental lighting as the days shorten.
In other words: 500 kg/year is a serious management target, achievable at best, not a promise. Actual yields will depend on your light, your climate and your consistency. Hence the wisdom of starting small, measuring, then expanding.
Integrating vertical towers into your greenhouse
In a 22 m² greenhouse, the most efficient layout contrasts two zones: heavy crops in the center (drip or Ebb & Flow, tall trellising) and vertical towers along the perimeter, where side light benefits the tiers. Lettuces and strawberries in towers, tomatoes in rows: each technology stays simple to stabilize individually, in line with the “one system at a time” principle.
Three points of vigilance: ridge height (a 1.5 m tower needs headroom for maintenance), access to reservoirs (frequent draining), and proximity to winter lighting. NFT, “often seen in professional operations,” is also “conceivable in a structured family greenhouse, notably to build a wall of lettuces or strawberries,” provided there is “fine management of flow rate, channel slope and solution level” (Habitats Durables, 2026).
The dream now has a plan. All that’s left is to put a price on it — and to know whether it will ever pay for itself.
Budget and profitability of a hydroponic setup
Price ranges by tier
The system alone costs nothing: budget for the structure if you’re moving outdoors. The market benchmarks per m² are as follows (Habitats Durables, 2026) : NFT €35/m², DWC €25/m², drip €30/m², wick €15/m². On the structure side: plastic tunnel greenhouse €40/m², glass or polycarbonate greenhouse €90/m², indoor grow tent €65/m², covered outdoor shelter €10/m². For 22 m² of tunnel greenhouse, the structure therefore weighs roughly 900 to 1,000 €, excluding system and equipment. 2026 market data, to be checked against real quotes — prices move, sometimes a lot.
Calculating annual savings
No source publishes an official profitability calculation — let’s say it plainly. Here is an illustrative method, with explicit assumptions to adjust to your case.
Now picture two identical households, side by side. The first buys its lettuces and herbs at the store every week. The second harvests theirs next to the kitchen window. The first pays, week after week. The second waits for the lettuce to grow.
Assumptions: a household consuming 2 lettuces and fresh herbs per week, plus a few tomatoes in season — roughly 4 to 6 € of equivalent weekly purchases at full production. A small, well-run DWC system covers a good part of that need. On the other side: nutrients (~10–15 €/month), seeds (~10–20 €/year, organic packet at ~3.40 € ; Permacademy), modest water and electricity for a small setup. The net saving typically falls between 100 and 200 €/year for a small system — and potentially several hundred euros for a productive 22 m² greenhouse yielding several hundred kilos of vegetables. Orders of magnitude, not measurements. Keep that in mind.
Estimated payback period
The formula fits on one line: payback = investment ÷ annual saving. Two illustrative examples, based on the assumptions above:
- DWC kit at 150 € ÷ 150 €/year ≈ 1 year ;
- Complete 22 m² greenhouse (structure + system + instrumentation, ~2,500 to 4,000 €) ÷ 500 to 1,000 €/year of produced value ≈ 3 to 6 years.
One year for the kit. Three to six years for the greenhouse.
Add the non-monetary benefits, which weigh heavily in the decision: harvest all year round, controlled sanitary quality, educational value — not to mention the pleasure, often cited by practitioners, of your first home-grown lettuce. To go further on this scenario, our complete guide to the 22 m² hydroponic greenhouse details the sizing step by step.
Before you pull out the order book, five questions come up in every beginner conversation: space, permits, winter, tonnage, maintenance. The answers, no detours.
FAQ — Your questions about hydroponics
How much space do you need?
No minimum area is required for private use. A kit fits in under 10 m²; a balcony or a corner of an office is enough to get started (Croquepousse ; bsness.fr). A 4 to 6 m² greenhouse already hosts a complete compact system of lettuces, herbs and a few tomatoes. Urban micro-farms run from 20 to 100 m², professional greenhouses start at 600 m² (bsness.fr).
Do you need a building permit?
Nothing to declare for an indoor system. For an outdoor greenhouse, the general schedule of the planning code applies: under 5 m², no formalities; from 5 to 20 m², prior declaration (1-month review); over 20 m², building permit (2 months) (service-public.fr). A detail few guides mention: decree no. 2021-1915 of December 31, 2021 (Climate and Resilience law) created a derogatory regime for plant production greenhouses — up to 2,000 m² and 4 m high, they are exempt from formalities in urban zones and subject to a simple prior declaration elsewhere (Légifrance). Thresholds can be lowered in protected areas: always check with your town hall and the local planning scheme before starting work.
Can it be used in winter?
Yes, with two caveats. Indoors, the seasons don’t matter: with 12 to 16 hours of lighting per day and a dark night period, a lettuce harvest in January is easily within reach (Semences du Jardin ; Croquepousse). Under a greenhouse, compensate for the shorter days (8-9 h in winter) with supplemental lighting and plan for heating to maintain minimums — 8 °C for leafy crops, 15 °C for tomatoes (Aquaponie-maison). The energy line then becomes your main point of vigilance.
How many kg of vegetables per year?
No consolidated official figure has been published for France — better to tell you that straight than to make something up. Professional orders of magnitude mention 50 to 60 kg/m²/year for hydroponic greenhouse tomatoes and 8 to 12 annual cycles for NFT lettuce, data to be confirmed with the CTIFL. For a small home system, think in terms of covering household needs (lettuces and herbs year-round) rather than tonnage. For a well-run 22 m² greenhouse, a target of a few hundred kilos per year remains achievable under good conditions (see our detailed simulation above).
What maintenance should you plan for?
Count on 15 to 30 minutes per week for a small system, and about 10 minutes for an automated one (Amperel, 2026). The typical routine: a glance every one to two days (water level, roots, pump, algae); a check and adjustment of pH and EC every week; a complete drain and rinse of the reservoir every one to three weeks, depending on temperature, reservoir size and plant consumption. Sources differ slightly on the ideal draining frequency (“every two weeks” at Croquepousse, “no universal frequency, 1 to 3 weeks” at Semences du Jardin): watch your solution, and it will tell you.
Conclusion — Move on to production with hydroponics
You now know everything Claire didn’t when she filled her watering can: the principle and its limits, the four families of systems, the plants that forgive and those that punish, the real budgets, the planning rules, the seven mistakes that bury a project. Soilless growing holds no more secrets for you. All that remains is the first lettuce — the one you never harvest without having dared to plant.
In 30 seconds, you can find out whether hydroponics belongs in your home: an opaque container, an air pump, clay pebbles, a punnet of lettuce — €25 to 50, two weeks, and you’ll know. Or you can leave your harvests to the mercy of the sky and the watering can, like Claire.
Your call.
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