The Germination Time for Growing Romaine Lettuce

Germination Period

• Romaine lettuce may be started with seed sown directly outdoors, with transplants or with seed started indoors. Lettuce does not tolerate very cold or very hot temperatures and germinates best in a soil temperature of 40 to 80 degrees Fahrenheit. Under optimal conditions, the seeds germinate in three to 10 days. Certain varieties have a faster germination rate when exposed to more light. When planting in cooler weather, light does not affect germination rate. But if planting in warm weather, cover seeds lightly for better light exposure.

Sowing Tips

• Sow romaine lettuce seeds at a shallow depth of 1/8 to ¼ inch with a spacing of 1 to 3 inches. After germination, thin plants to 8 to 12 inches. Space rows 1 to 1½ feet apart. Use healthy seeds treated with fungicide as this reduces chances of damping off. The North Carolina State University Extension recommends using about 1 lb. of seed per acre. Though young seedlings tolerate short periods of freezing weather, extended exposure is likely to damage succulent seedlings.

Soil

• Romaine lettuce grows well in a variety of well-drained soils but growth is optimal in moist, fertile soil preferably amended with organic material. Performing a soil test will help to determine the soil pH, recommended between 6.0 to 6.7, and the amount of lime fertilizer required to fix pH if required. In soils with high levels of phosphorus and potassium, add 500 to 600 lbs. of 10-20-20 fertilizer per acre. Apply half after plants are established and growing. Apply the rest after judging the rate of growth.

Water

• Irrigate the plants with frequent and light watering. This will lead to rapid leaf development and high-quality lettuce. Avoid overwatering romaine, especially in heavy, clay soil, as this makes plants prone to diseases, scalding of leaf margins and soft growth. Apply organic mulch as this will not only conserve soil moisture but also moderate soil temperatures. Harvest romaine when a long, medium dense head has developed.