How to Grow Romaine Lettuce Plants

Romaine is also called cos lettuce.
Romaine is also called cos lettuce. (Image: Jupiterimages/ Images)

Romaine produces a loose head of crisp leaves that are suitable for use in salads, sandwiches or as a garnish. The leaves grow upright, so romaine doesn't require a lot of space to grow its long leaves. Like all lettuce, romaine grows as a cool season crop, but it doesn't go to seed as quickly as head lettuce varieties. The seeds germinate quickly, typically within a week, so romaine is usually directly sown in the garden bed.

Things You'll Need

  • Compost
  • Fertilizer
  • Spade or tiller
  • Rake
  • Burlap

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Turn a 1-inch layer of compost into the top 4 to 6 inches of the garden soil with a tiller or spade. Add 2 lbs. of 5-10-10 blend fertilizer to every 50 square feet of bed and turn it into the soil. Rake the soil surface to smooth it and to break up any large soil clumps.

Water the bed until the top 6 inches of soil are thoroughly moistened but not soggy. Watering the bed after sowing the seed can wash away the small romaine lettuce seeds, so it's best to water prior to seeding.

Sow the romaine seeds on the soil surface, planting approximately four seeds per foot of row. Space the rows 12 inches apart.

Cover the seeds with a 1/4-inch layer of soil after planting. Lay moistened burlap over the top of the bed to keep the moisture in the soil during germination. The bags also prevent the seeds from washing away in the event of rainfall.

Check under the bags for sprouts daily. Remove the bags once the romaine seeds begin germinating and breaking through the soil surface.

Thin out the romaine seedlings once they grow in their second set of leaves. Pull the excess seedlings so the remaining plants are spaced 4 inches apart for small types and 8 inches apart for large types. Refer to the seed packet for the recommended spacing for your romaine variety.

Water the romaine one to two times a week -- often enough to keep the top 6 inches of soil moist but not soggy. Romaine requires approximately 1 inch of water a week.

Harvest the outer leaves from the romaine plants once they are 4 to 6 inches long and have developed prominent ribs. Alternatively, harvest the entire plant once it reaches the desired size by cutting the plant off at the soil surface.

Tips & Warnings

  • Plant romaine lettuce in the garden in mid-spring once the average daily temperature is 45 degrees Fahrenheit or above. Romaine goes to seed in hot weather.


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