Lettuce Handbook

Spacing

Proper plant spacing is an important aspect of lettuce production.  In production situations where plants are placed in close proximity to one another, the plants are shaded by neighboring plants.  Shaded plants become tall and thin, "reaching" for extra light.  This produces an unacceptable head of lettuce.  Spacing plants far enough away from their neighbors allows the plants to grow outward.  Once the leaves of adjacent plants start to touch one another, the plants should be re-spaced. In the described hydroponic lettuce production, the spacing is scheduled for Day 11, during the transfer from the germination area to the pond area, and also on Day 21, when the plants are growing in the greenhouse.