Moving beyond soil
Hydroponics delivers water, oxygen, and nutrients directly to roots in controlled solutions or inert media. Greenhouse operators choose systems based on crop type, capital cost, labor, and water recycling goals.
Major system types
- NFT (nutrient film technique) — thin solution film flows through channels; excellent for leafy greens but vulnerable to pump failure.
- Drip irrigation in bags or slabs — rockwool, coco coir, or perlite substrates with scheduled fertigation; standard for tomatoes and peppers.
- Deep water culture (DWC) — roots suspended in aerated tanks; high oxygen demand requires reliable air pumps.
- Ebb and flow (flood tables) — periodic flooding of trays; versatile for bedding plants and herbs.
Solution management
Monitor EC (electrical conductivity) for total dissolved salts and pH for nutrient availability. Iron, manganese, and phosphorus availability shift sharply below pH 5.5 or above 6.5. Recirculating systems require regular solution analysis and biofilter management to prevent pathogen buildup.
Root zone oxygen
Even in hydroponics, oxygen is the limiting factor more often than nutrients. Dissolved oxygen drops as solution temperature rises above 25°C — chillers or increased aeration become necessary in warm climates.