Black Seeded Simpson (BSS) lettuce is a widely popular, heirloom loose-leaf variety cherished for its reliable growth and excellent flavor. This lettuce is a fantastic starting point for new gardeners because it is remarkably forgiving and grows quickly. Its bright green, ruffled leaves offer a tender texture and mild taste, making it a versatile addition to any meal. The BSS is also known for its enhanced heat tolerance compared to many other lettuce types, allowing for an extended growing season. This fast-maturing crop can be ready for harvest in just over a month, providing a continuous supply of fresh greens with minimal effort.
Site and Timing Requirements
Black Seeded Simpson is fundamentally a cool-weather crop. The best times for planting are early spring, as soon as the soil can be worked, and late summer for a fall harvest. Lettuce seeds germinate effectively at low soil temperatures, often down to 40°F, but germination becomes erratic or dormant when soil temperatures rise above 75°F.
To maintain a steady supply of greens, gardeners can employ succession planting, sowing a new batch of seeds every two to three weeks until the weather becomes too warm. While BSS shows good heat tolerance, afternoon shade is highly beneficial, especially in warmer climates, to prevent the plant from bolting prematurely. In cooler regions, full sun is acceptable, but selecting a location that receives partial shade during the hottest part of the day will help keep the leaves sweet and tender.
Lettuce thrives in well-drained, loose soil that is rich in organic matter, such as compost or well-rotted manure. The roots of the lettuce plant are shallow, so a fertile top layer is important for rapid and healthy growth. An ideal soil pH for Black Seeded Simpson ranges from slightly acidic to neutral, specifically between 6.0 and 7.0.
Sowing the Seeds
Direct sowing the seeds into the garden is the most common and effective method for Black Seeded Simpson lettuce. The seeds should be planted very shallowly, only about 1/8 to 1/4 inch deep, and covered with a light layer of fine soil. Lettuce seeds require light for optimal germination, which is why a very shallow planting depth is critical.
Sow seeds roughly one to two inches apart in rows spaced 12 to 18 inches apart. Once the seedlings have developed two to three true leaves and are about two inches tall, they must be thinned to a final spacing of six to ten inches between plants.
Thinning involves removing the weaker seedlings to ensure the remaining plants have adequate air circulation and nutrients. To avoid disturbing the roots of the keepers, cut the unwanted seedlings at the soil line with a small pair of scissors rather than pulling them out. After sowing, the area should be watered gently with a fine mist to avoid washing the shallowly planted seeds out of the soil.
Ongoing Maintenance and Harvesting
Consistent moisture is paramount for Black Seeded Simpson lettuce, as dry soil is the primary cause of leaf bitterness and bolting. Due to their shallow root systems, lettuce plants require regular, deep watering, particularly during dry periods, to ensure the soil remains evenly moist. Applying a layer of mulch, such as clean straw or shredded leaves, can help the soil retain moisture and stabilize the temperature around the roots.
Lettuce is not a heavy feeder, but it benefits from soil that is rich in nitrogen to support rapid leaf production. A side dressing of compost or a light application of a balanced organic fertilizer every four to six weeks can provide sufficient nutrients. Bolting, the process where the plant sends up a central flower stalk to set seed, signifies the end of the harvest and causes the leaves to become bitter. Keeping the plants cool and well-watered is the best way to delay this natural process.
The Black Seeded Simpson variety is perfectly suited for the “cut-and-come-again” harvesting method, allowing for continuous production from a single planting. Begin harvesting the outer, largest leaves when they are usable size, typically around 40 to 50 days from planting. When cutting, take care to leave the central growing point, or the heart, intact so the plant can quickly regenerate new leaves.