Romaine lettuce, known for its distinct upright structure and crisp texture, is a favorite among gardeners and consumers. Its success depends on knowing the precise moment and method for harvest. Romaine can be picked in several ways, allowing for either a single large yield or a continuous supply of fresh leaves. Understanding the plant’s visual cues and growth cycle is the foundation for maximizing its flavor and extending the harvest period.
Visual Indicators of Romaine Maturity
The optimal time to harvest Romaine is determined by the plant’s physical appearance. While many varieties mature approximately 60 to 70 days after planting from seed, visual indicators are more reliable. The leaves should display a deep, uniform green color and possess a crisp quality, indicating high water content.
The full head should form a loose, upright structure, sometimes referred to as a Cos shape, which is not as tightly packed as an iceberg variety. Full-sized Romaine heads are ready when they reach a height between 10 and 12 inches, though smaller varieties like Little Gem may be ready around six inches. Harvesting at this mature stage ensures the best balance of sweetness and minimal bitterness.
Harvesting the Entire Head
Removing the entire head is the most efficient method for a single, substantial harvest. This technique is often used when a large quantity is needed or when the growing season is ending due to rising temperatures. For the best quality, harvest early in the morning before the day’s heat causes the leaves to lose crispness.
Use a sharp, clean knife or garden shears to cut the head cleanly from the root base. The cut should be made one to two inches above the soil line, leaving the plant’s basal plate intact. Leaving this small portion of the stem allows for a secondary, smaller yield of leaves to sprout, slightly extending production.
The Cut-and-Come-Again Method
Home gardeners often prefer the cut-and-come-again technique, which allows for repeated harvesting from the same plant. This method focuses on removing only the outer, older leaves while protecting the central growing point, or heart, of the Romaine head. The plant’s energy is then directed toward producing new leaves from the center, maintaining a continuous supply of tender greens.
When harvesting, select the largest, most developed outer leaves and snip or snap them off near the base. Leave at least four to six inner leaves untouched, ensuring no more than one-third of the plant’s total foliage is removed during a single session. The plant requires about one to two weeks to regenerate new growth before the process can be repeated.
Managing Late-Season Bolting
Romaine lettuce is a cool-season crop highly sensitive to environmental stress, particularly heat. When temperatures consistently rise above 75 to 80 degrees Fahrenheit, or when daylight hours become too long, the plant initiates flowering, a process known as bolting. Bolting is identified as the plant rapidly elongating and sending up a tall, central flower stalk.
Once bolting begins, the lettuce leaves quickly develop a bitter flavor and a tougher texture. This change is due to the increased concentration of milky, bitter compounds produced as the plant shifts energy into reproduction. To delay this process, provide afternoon shade to cool the plant and ensure the soil remains consistently moist, mitigating drought stress. Any Romaine that has begun to bolt should be harvested immediately to salvage the remaining edible leaves before the bitterness becomes too pronounced.