AnyponicsPlanning · Yields
How much lettuce can I grow?
Each hydroponic lettuce site produces a head about every 35 days, so each plant site gives you about 0.87 heads a month. A site needs about a quarter of a square foot of growing area. The rest is how much floor you can give it.
Heads per month by space
| Setup | System | Plants | Harvest /mo | Build cost | Running /mo |
|---|---|---|---|---|---|
| 2×4 ft, as much as fits | Vertical Tower | 28 | 24 heads (8 lb) | $1,188 | $26 |
| 4×4 ft, as much as fits | Vertical Tower | 56 | 49 heads (16.1 lb) | $1,612 | $35 |
| 4×8 ft, as much as fits | Vertical Tower | 113 | 98 heads (32.5 lb) | $3,038 | $68 |
| 6×8 ft, as much as fits | Vertical Tower | 170 | 148 heads (48.9 lb) | $4,240 | $85 |
| 8×10 ft, as much as fits | DWC | 224 | 195 heads (64.4 lb) | $1,594 | $117 |
How many plants do you need?
Work backwards from what you eat. A household that eats a head of lettuce every other day needs about 15 heads a month, so about 18 plant sites. Allowing for a few failures and a harvest that comes in waves, round up to 20: that system costs about $646 and grows 17 heads a month.
- One head a week: about 5 sites.
- A salad every day for two: about 30–40 sites.
- Selling or sharing with neighbours: 100+ sites, which means a dedicated basement or garage area.
The maths behind the table
- Spacing: about 4 heads per square foot on 6-inch centres in flat systems; vertical towers fit about 3.5 per square foot of floor by stacking.
- Walkways: flat systems leave about 30% of the floor free so you can reach the plants.
- Cycle: 35 days from transplant, using the low end of Cornell's controlled-environment lettuce trials (about 150 g a head).
- Stagger planting. If you plant every site on the same day, you get every head on the same day. Plant a quarter of the sites each week for steady harvests.