NFT channel systems
Sloped channels with a thin nutrient film give fast growth, low water volume and simple mechanised transplanting and harvest.
Lettuce & Leafy Greens
Lettuce Greenhouse & Leafy Green Production
Lettuce and leafy greens are the fastest-cycling greenhouse crops, which makes them the most sensitive to throughput and labour efficiency. A lettuce greenhouse succeeds on cycle discipline, uniform light and reliable root zone temperature rather than on maximum technology.
- Cycle length
- 28 – 45 days
- Cycles per year
- 8 – 12
- Annual yield
- 40 – 80 kg/m²
- Plant density
- 20 – 28 heads/m²
01
Growing requirements
| Parameter | Target | Notes |
|---|---|---|
| Day temperature | 18 – 22 °C | Above 25 °C triggers bolting and bitterness |
| Night temperature | 12 – 16 °C | Supports firm heads and good leaf texture |
| Root zone temperature | 18 – 22 °C | The single biggest driver of tipburn risk |
| Nutrient EC | 1.2 – 1.8 mS/cm | Adjusted by season and light level |
| pH | 5.5 – 6.2 | Keeps micronutrients available |
| Relative humidity | 65 – 75% RH | Excess humidity causes tipburn and downy mildew |
02
Recommended systems
Deep water culture ponds
Large solution volume buffers root temperature, which is a decisive advantage in hot climates.
Multi-span or glass with strong ventilation
Leafy greens need air exchange more than insulation; ventilation area and screening drive summer viability.
Evaporative cooling and shading
Pad-and-fan or fogging with movable shade holds the crop below the bolting threshold through summer.
Recirculation with UV disinfection
Closed-loop nutrient reuse with disinfection reduces water and fertiliser cost and limits root disease spread.
Nursery and transplant area
A dedicated propagation zone keeps the main greenhouse in production and makes weekly cycle planning reliable.
03
Climate management
Heat avoidance
Ventilation capacity, shading and evaporative cooling are sized against summer peak conditions, because bolting eliminates crop value outright.
Root zone temperature control
Solution cooling, tank shading and pipe insulation hold the nutrient solution in range and prevent oxygen depletion.
Tipburn prevention
Air movement, humidity control and calcium availability are managed together — tipburn is a transpiration problem, not a fertiliser problem.
Light steering
Diffuse glazing and shade give uniform light for uniform head weight; supplemental lighting stabilises winter cycle length.
Cycle and hygiene discipline
Fixed weekly sowing, transplanting and harvesting slots with channel cleaning between cycles keep throughput and food safety consistent.
04
Expected benefits
8 – 12 harvests per year
Short cycles turn capital quickly and allow production to be matched closely to contracted demand.
Consistent head weight and quality
Uniform hydroponic conditions produce the specification consistency retail and food service buyers require.
Very high water efficiency
Recirculating systems use a fraction of field water use, which is decisive in water-constrained regions.
Clean, traceable product
Soil-free production with recorded inputs supports premium pricing and simplifies food safety certification.
FAQ
Lettuce & Leafy Greens questions
Common technical and commercial questions about lettuce greenhouse.
What is the best system for growing lettuce in a greenhouse?
NFT channel hydroponics is the most widely used commercial system for greenhouse lettuce because of fast growth, low water volume and easy mechanisation. Deep water culture is preferred in hot climates where the large solution volume helps stabilise root zone temperature.
How many lettuce crops can be grown per year in a greenhouse?
A commercial hydroponic lettuce greenhouse produces 8 to 12 crops per year, with cycles of 28 to 45 days depending on season, light level and target head weight. A separate nursery area is essential to maintain a consistent weekly harvest schedule.
Why does greenhouse lettuce bolt or develop tipburn?
Bolting is caused by excessive temperature, typically above 25 °C, or by high root zone temperature. Tipburn is caused by rapid growth combined with insufficient calcium transport, driven by low air movement and high humidity. Both are climate and irrigation design problems rather than variety problems.
How much does a hydroponic lettuce greenhouse cost?
Hydroponic lettuce greenhouses typically cost 110 to 200 USD per square metre delivered and installed, including structure, cooling, NFT or DWC system, water treatment and controls. In hot climates the cooling package is often the largest single cost component.
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