Harvest romaine lettuce by pulling the entire plant from the ground or trimming it just above the soil level. Monitor the plant for signs of maturity to avoid letting the plant become overly matured, which imparts a bitter flavor. Time the harvest for morning for optimal texture.
- Create a reminder
Note the planting date and the earliest maturity date on a calendar as a reminder to begin checking the lettuce for signs of maturity. Most romaine lettuce varieties typically take 55 to 65 days to mature.
- Remove the outer leaves
Trim outer leaves from the head of romaine as it grows, if desired. These baby romaine leaves are usually ready for harvest within a month of planting the romaine lettuce.
- Monitor the plant for firmness
Once the plant's earliest maturity date approaches, begin checking the plant by gently pressing on the heart. Mature romaine lettuce should be firm, but still compressible, with 30 to 35 leaves. Avoid allowing the romaine to become overly mature.
- Harvest in the morning
Harvest romaine by pulling the whole head from the ground and trimming the bottom inch. Alternatively, harvest each head by cutting it approximately 1 inch above the soil line. This allows the plant to develop a second head. For maximum crispness, time the harvest for the morning.