The history of hydroponics is really the history of one question: what is a plant actually made of? It took nearly 300 years and several wrong turns to answer it. Only once the answer was known did growing without soil become feasible.
The Hanging Gardens: a story worth questioning
Almost every text about hydroponics opens with the Hanging Gardens of Babylon in the 6th century BC. The problem: not a single Babylonian source mentions them — not the chronicles, not the building records, and not Nebuchadnezzar II himself, who otherwise documented his construction projects in detail. Every description comes from Greek and Roman authors writing centuries later who had never been there.
In 2013 the Oxford Assyriologist Stephanie Dalley made a convincing case that the gardens did exist — but in Nineveh, around 700 BC, under the Assyrian king Sennacherib, who built aqueducts and water-raising screws for them. Even then: that was irrigated soil, not growing in water. A beautiful image, but not hydroponics.
Closer to the mark are the Aztec chinampas from roughly 1200 onwards: artificial islands of mud and reed on Lake Xochimilco, where roots had permanent access to water. Soil was still part of the equation there too.
1648 and 1699: the first two measurements
The Flemish scientist Jan Baptist van Helmont planted a 2.3 kg willow shoot in a container with 90.7 kg of dried soil and watered it with rainwater only for five years. The willow then weighed 76.7 kg, while the soil had lost just 57 grams. His conclusion, published posthumously in 1648: the plant is made of water. He was wrong — carbon dioxide in air was unknown to him — but it was the first quantitative experiment in plant physiology.
In 1699 the Englishman John Woodward went one step further. He grew spearmint in four kinds of water: distilled rainwater, water from the Thames, city conduit water, and water with garden soil stirred into it. It grew best in the dirtiest water. His conclusion: plants do not grow from water, they grow from what is dissolved in it. That is the core idea of hydroponics — 240 years before it had a name.
The 1860s: Sachs and Knop write the recipe
Once chemistry could finally identify individual elements, the German botanists Julius von Sachs (1860) and Wilhelm Knop (1861, recipe refined in 1865) published the first reproducible nutrient solutions in which a plant completed a full cycle to seed. Knop's solution is still used in classroom experiments today.
| Salt in Knop's solution (1865) | Element it supplies |
|---|---|
| Ca(NO₃)₂ — calcium nitrate | nitrogen + calcium |
| KNO₃ — potassium nitrate | nitrogen + potassium |
| KH₂PO₄ — monopotassium phosphate | phosphorus + potassium |
| MgSO₄ — magnesium sulphate | magnesium + sulphur |
| FeSO₄ in traces | iron |
The micronutrients arrived much later, one at a time: manganese 1922, boron 1923, zinc 1926, copper 1931, molybdenum 1939 and chlorine only in 1954. Every modern bottle of hydroponic fertiliser is the sum of those separate discoveries — more on that in Nutrients.
1937: the word “hydroponics”
William Frederick Gericke at the University of California, Berkeley grew tomato vines over 7 metres tall in plain tanks of nutrient solution during the late 1920s and 1930s. The term hydroponics — from Greek hydro (water) and ponos (labour) — was suggested to him in 1937 by his colleague W. A. Setchell. Gericke also oversold the method badly, which is why his colleagues Dennis Hoagland and Daniel Arnon published a sober counter-study in 1938 with the Hoagland solution, still the laboratory standard.
The science was finished in 1865. The marketing arrived in 1937. The balcony had to wait until the 2020s.
War, islands and space
The first serious applications were logistical, not ecological. Where there is no usable soil, hydroponics was the only way to get fresh vegetables without weeks of shipping.
- Late 1930s — Wake Atoll: Pan American Airways grew vegetables on bare coral for the crews and passengers of trans-Pacific flights.
- 1943–1946 — Habbaniya (Iraq) and Bahrain: hydroponic beds supplied Allied desert bases.
- 1946–1950s — Chofu near Tokyo: around 22 hectares, the largest hydroponic facility of its time, built for the occupation forces.
- 1965–1973 — Littlehampton, England: Allen Cooper develops NFT, the thin film of solution running continuously past the roots.
- From 1982 — NASA, the CELSS programme: research into closed food systems for long-duration missions.
- 2015 — ISS: astronauts eat lettuce grown in orbit for the first time, from the Veggie chamber.
NASA also drove the popularity of aeroponics: research in the 1990s showed that roots suspended in a mist of nutrient solution get more oxygen and grow faster. That idea now lives on in home towers.
Today: greenhouses, numbers and a reality check
| Region | Area under glass or plastic | Note |
|---|---|---|
| Netherlands | around 10,000 ha | tomatoes at 50–100 kg/m² per year versus 5–10 kg/m² in the field |
| Almería, Spain | over 30,000 ha | visible from space, but much of it still grows in sand and soil, not in solution |
| Japan and South Korea | hundreds of “plant factories” | fully enclosed rooms, LED light only |
The past decade also brought a wave of warehouse vertical farms — and the hangover. AeroFarms entered bankruptcy proceedings in 2023, Infarm pulled out of most European markets the same year, and Bowery Farming shut down in 2024. The cause was not biology but electricity: lighting and cooling eat the margin as soon as energy gets expensive.
At home the opposite is true. A pump of around ten watts plus daylight costs practically nothing. What genuinely changed is manufacturing: 3D printing makes vertical towers viable in small batches, without injection moulds costing tens of thousands. The science is from 1865; the availability is from the 2020s.