UK Indoor Lettuce Yield Data: DWC vs NFT benchmarks
Real trial data from our Metro Farms shelves — sortable by variety, system and DLI so you can benchmark your own grow against proven indoor UK figures.
Yield comparison: DLI 17 mol/m²/d, all varieties
The chart below compares fresh-weight yield per plant at DLI 17 across both systems. Oakleaf is the standout performer in DWC; all varieties show meaningful gains from the higher daily light integral.
Fresh-weight yield (g/plant) at DLI 17
Full dataset — sortable
Click any column header to sort. All 14 trial runs included. DLI is daily light integral in mol/m²/d; yield is fresh weight per plant at harvest.
| Variety | System | DLI | Yield (g/plant) | Days to harvest | Water (L/plant) |
|---|---|---|---|---|---|
| Butterhead | DWC | 12 | 85 | 28 | 4.2 |
| Butterhead | DWC | 17 | 118 | 25 | 5.1 |
| Butterhead | NFT | 12 | 78 | 30 | 3.8 |
| Butterhead | NFT | 17 | 109 | 27 | 4.6 |
| Cos/Romaine | DWC | 12 | 72 | 32 | 4.8 |
| Cos/Romaine | DWC | 17 | 105 | 29 | 5.9 |
| Cos/Romaine | NFT | 12 | 66 | 35 | 4.2 |
| Cos/Romaine | NFT | 17 | 97 | 31 | 5.3 |
| Oakleaf | DWC | 12 | 92 | 26 | 3.9 |
| Oakleaf | DWC | 17 | 128 | 23 | 4.7 |
| Oakleaf | NFT | 12 | 84 | 28 | 3.5 |
| Oakleaf | NFT | 17 | 118 | 25 | 4.2 |
| Little Gem | DWC | 17 | 95 | 24 | 4.4 |
| Little Gem | NFT | 17 | 88 | 26 | 3.9 |
14 trial runs. EC 1.4–1.6 mS/cm, pH 6.0±0.2, 20/4 light schedule, 20–22°C air, 65% RH. Transplanted at 10-day-old seedlings. Data is mean of 3 replicate trays per condition.
People also ask
Which hydroponic system produces the most lettuce?
In our UK indoor trials, DWC (Deep Water Culture) produced 8–13% higher fresh-weight yield than NFT across all varieties at equivalent DLI. The larger reservoir volume in DWC buffers nutrient and pH fluctuations, reducing plant stress. NFT has lower water use per plant (3.5–4.6L vs 3.9–5.9L in DWC) and is preferred at commercial scale where water efficiency and harvest logistics matter more than maximum per-plant yield.
What DLI is best for indoor lettuce?
Our data shows a 25–40% yield increase when DLI moves from 12 to 17 mol/m²/d, with no signs of light saturation at 17. Most professional lettuce operations target 15–20 mol/m²/d. Below 10 mol/m²/d, growth is noticeably suppressed; above 20 mol/m²/d, leafy greens can show tip-burn from elevated transpiration unless calcium levels and airflow are increased in parallel.
How long does indoor lettuce take to grow?
In our trials, from transplant (10-day seedlings) to harvest: Oakleaf at DLI 17 in DWC took 23 days (fastest), Butterhead at DLI 17 took 25–27 days, and Cos/Romaine at DLI 12 in NFT took 35 days (slowest). Total time from seed is roughly 10 days longer in each case. Higher DLI shaves 3–5 days off harvest time in all varieties.
Which lettuce variety is best for indoor growing?
Oakleaf delivered the highest absolute yield (128g/plant, DWC, DLI 17) and the fastest harvest. Butterhead is the most forgiving under variable conditions and the most commercially familiar variety. Cos/Romaine takes longest but has a premium price point in UK retail. Little Gem is compact — suited to tight spacing — and matures quickly at high DLI.
The right light is the biggest lever
DLI 17 adds 38% yield over DLI 12 with no other changes. The Samsung-chip board we use on our shelves is the one that produced these numbers.