Hydroponics is growing plants without soil, in water enriched with mineral nutrients. The roots grow directly in the nutrient solution or in an inert substrate (rockwool, coco, clay pebbles) that merely holds the plant in place.
Why the plant does not actually need soil
This surprises most people: a plant does not absorb “soil” from the ground. It draws water and dissolved mineral ions — nitrogen, phosphorus, potassium, calcium, magnesium and trace elements. Soil is only the middleman: it stores water, holds minerals and gives the roots something to grip.
Dissolve those same ions in water and bring them to the roots, and the plant does exactly the same job — just without the searching. Photosynthesis, growth and flavour proceed identically, because chemically the plant receives the same molecules.
A plant cannot tell potassium from compost apart from potassium in a nutrient solution. To the root it is the same ion.
How the system works in practice
- Water reservoir — holds the nutrient solution, typically 20 to 50 litres.
- Pump — quietly lifts water up to the plants, usually in intervals.
- Root zone — roots hang in the solution or the solution trickles over them.
- Return — surplus water flows back to the reservoir by gravity. The loop is closed.
That closed loop explains the biggest advantage: water does not drain away into the ground or evaporate across a large surface, it circulates. This is why hydroponic systems use up to 90 % less water than a conventional bed.
What works well — and what does not
| Excellent | Works with support | Better in soil |
|---|---|---|
| Lettuces of all kinds | Tomatoes (need staking) | Potatoes |
| Culinary herbs | Peppers and chilli | Carrots |
| Spinach, chard, rocket | Strawberries | Beetroot, root vegetables |
| Lamb's lettuce, pak choi | Cucumbers | Pumpkins and squash |
The rule of thumb is simple: the more leaf a plant produces, the better it suits hydroponics. Root vegetables need room to swell in a substrate and belong in soil.
Advantages and limits, honestly stated
- ✅ Up to 90 % less water, because the system is closed.
- ✅ No weeds and no digging — there is no soil for weeds to germinate in.
- ✅ Faster growth, because roots spend no energy searching for nutrients.
- ✅ Growing on 0.5 m² of balcony instead of a garden bed.
- ⚠️ It needs electricity for the pump (only a few watts on a tower).
- ⚠️ EC and pH must be measured — not complicated, but not skippable.
- ⚠️ During a power cut the system pauses; roots cope for several hours without trouble.
Is this “artificial food”?
No. The mineral nutrients in the solution are the same salts found in soil — only in a known, measured amount. The difference is that you know exactly what went into the water, whereas with soil you depend on whatever is already in it (including heavy metals or spray residues from the past).
The plant itself is botanically identical. Lettuce from a tower and lettuce from a garden are the same species, the same genes, the same growth process. Read more about common misconceptions in Myths and Facts.