Timing

• Lettuce is a cool season vegetable. According to Ohio State University Extension, the ideal temperatures for growing lettuce is 45 to 65 degrees. Romaine is more heat-tolerant than other types of lettuce, and it can also stand up to light frosts, so it's a smart choice if your climate can be a bit unpredictable.
  
  

Planting

• Schedule planting about 80 days before the expected first frost dates. If you live in a warm climate, starting seeds indoors can ensure timely germination. You can then transplant seedlings once the weather has cooled. Seeds should be planted no more than 1/4 inch deep, and plants should be spaced 8 to 12 inches apart. Plant crops in succession every two weeks to ensure a steady harvest throughout the season.
  
  

Soil

• The University of Minnesota Extension recommends a soil pH of 6 to 6.5, so it is beneficial to have your soil tested before the planting season. Romaine requires rich, moisture-retaining soil, so work compost or well-rotted manure into the soil at a rate of about 1/4 lb. per 5 square feet. Since lettuce is shallow-rooted, it needs moisture and nutrients to be kept close to the surface.
  
  

Water and Feeding

• It is essential that lettuce is watered regularly. Erratic watering or allowing plants to dry out can result in uneven growth. Water at about an inch per week in cool, moist weather. If the weather gets hotter or drier, your plants may require as much as 1 to 2 gallons of water per square foot of planting per week. The University of Minnesota Extension recommends a 4-inch layer of organic mulch to retain soil moisture.
  
  With the rich soil, no additional fertilizing is necessary unless growth is slow. In this case, application of a nitrogenous fertilizer or an organic liquid feed can help boost growth rates.
  
  

Pests

• Birds can be a problem when seedlings emerge because they love the snack. Rig a protective cover with bird netting on stakes. Alternately, cut the bottom off of a clear plastic soda bottle and cover the seedling with it. Sink the edges of the bottle slightly into the ground so it won't fall over, and remove the cap to allow air flow.
  
  Beetles and aphids are the biggest threats to romaine lettuce, notes the American Horticultural Society. An organic way to repel these pests is to inter-plant basil or cat mint in your lettuce bed.
  
  

Disease

• Lettuce may be prone to mildew, mold or mosaic virus. Purchasing disease-resistant varieties can help prevent a lot of potential problems. Make sure the lettuce has proper drainage. While soil should be damp, it should not be soggy or muddy. Water plants early in the morning so the leaves will dry before nightfall. Prolonged wet foliage can encourage the growth of mold or viruses.