Growing Lettuce

Introduction

Lettuce, most often grown as a leaf vegetable and sometimes for its stem and seeds, originated in the Mediterranean area as a weed. The first documentation of cultivation begins in Ancient Egypt over 6,000 years ago, but it may have been cultivated in the Middle East prior to this. Ancient Egyptian artwork, especially tomb paintings, depicts different varieties of lettuce.

Types

There are different concepts of species within the genus Lactuca. It is unclear which distinct species are known; estimates vary from 50 to 75 so far.

Manoa Lettuce, a special mini head from University of Hawaii, is grown widely on all the Islands mainly due to its resistance to heat and tip-burn.

Germination & Propagation

Lettuce has a germination period of anywhere from 2 to 10 days. Maybe longer in colder conditions. Sow your seeds in fertile material at a approximately one quarter inch deep and water thoroughly. I suggest using starter pots. They need to be kept wet while the seeds germinate. You can water often, keep the pots in a tray with water in the bottom or cover the soil with plastic wrap until the seeds have sprouted.

Seeds are best stored in the refrigerator and can be purchased directly from us via our Seed Store. We get our seed stock directly from the College of Tropical Agriculture and Human Resources (C/T/A/H/R), University of Hawaii at Mānoa.

Planting

Lettuce is very suited and easy to grow in a pot. Larger pots can house multiple plants and can be perpetually harvested once the outer leafy material is being replaced by an inner leaf.

Lettuce beds should have transplants in rows about 12 to 18 inches apart with approximately 10 to 12 inches between each plant.

The ideal soil for growing lettuce is moist but well-drained. Use the Best Hawaiian Soil Mix once the seedlings have established themselves.

Sun and Water

Lettuce thrives and produces quicker when exposed to full sunlight. That said, it also grows well in light shade as well as under indoor growing lights of all kinds.

In warmest regions, try to select a growing spot that offers afternoon shade. Lettuce plants have very shallow root systems. Plants will need consistent watering.

Fertilizing

Lettuce, despite its size, is a fairly heavy feeder. Since it primarily produces leafy material a nitrogen dominant feeding program is needed. Top feeding with guano and watering with organic teas will stimulate the healthiest plants.

Harvesting

While one can certainly harvest the entire head, lettuce plants will consistently provide harvestable leafy material until such time that the plant starts "bolting"; anywhere from 65-130 days depending on location, temperature, the time of year and how often one harvests.

This process will cause the plant to become rather bitter as it transfers the majority of its energy into producing seeds. Cutting of the larger outer leafy material tends to stunt the plant's ability to bolt.

Once harvested the quality of leafy material will rapidly decline and is best consumed fresh.