Not just for Caesar salads, romaine lettuce, also known as cos lettuce, is an excellent choice of greens for your garden. These plants will develop narrow, upright, long leaves with a well-defined central rib. The leaves will bunch up into the familiar elongated head shape when the plant reaches maturity. The taste is slightly bitter, but delicious, with inner leaves being lighter in color and milder in flavor. Most varieties of this type have some heat and/or disease tolerance. Successive plantings every 2 weeks will give you plenty of salad greens throughout the season.
Coastal Green romaine is a taller variety of lettuce that can be harvested either for its hearts or for full leafy green heads. This variety is known for its tolerance to heat and its ability to grow throughout hot summer months without bolting so it’s a great option if you’ve put off starting your garden for a little longer than expected (don’t worry, we don’t judge!). Easy to grow, beautiful to look at, and packed with rich nutrients, this lettuce is a must-have for any summer garden.
Seed Depth: 1/8–1/4″
Space Between Plants: 8–10″
Space Between Rows: 6–8″
Germination Soil Temperature: 50–70°F
Days for Germination: 7–14
Sow Indoors: 4–6 weeks before average last frost date.
Sow Outdoors: 2–4 weeks before average last frost date. Plant successively every 3 weeks until 6 weeks before average first frost date. For a winter crop in warm climates, plant 2–4 weeks before average first frost date.
Grows best in cool weather and will survive mild frosts. Romaine lettuce can be grown as a winter crop in USDA Zones 8 and above. High temperatures will cause plants to bolt, and germination will be poor in temperatures above 80°F.
Natural: Full Sun. Prefers partial afternoon shade in warm weather.
Artificial: Grows well under fluorescent or LED lamps. Needs at least 12 hours of light daily; however, more is preferred. A 24-hour day cycle may result in highest yields.
Soil: Prefers loamy soils with a high amount of organic matter but are adaptable and will grow in most soil types. A pH between 6.0 and 6.8 will keep plants healthy and nourished.
Soilless: Seeds will germinate in soilless mixes, rockwool, and other soilless media.
Hydroponics: Will thrive in hydroponic systems including NFT, floating raft technique, or deep water culture.
Aeroponics: Will thrive in aeroponic systems.
Water: Requires moderate levels of water. Although this lettuce does not require a large quantity of water, it does require consistent watering. Ensure that soil is moist but not muddy.
Nutrients: Requires moderate to high levels of nutrients. Nitrogen-rich fertilizers such as blood meal will help lettuce plants grow full and succulent leaves. Potassium and phosphorus levels need to be adequate for good growth, as well.
Foliar: Application of foliar sprays containing nitrogen will keep plants healthy and strong.
Mulching: Mulch may be used around the plant to keep weeds down and protect the plants’ shallow root system from damage or competition.
Deficiency(s): A lack of phosphorous, potassium, and, most commonly, nitrogen can cause plants to wilt or be stunted in growth.
Rotation: Follow with a legume crop, like peas or beans, to replenish soil nitrogen levels.
Companions: Grows well with carrots, collards, onions, strawberries, beets, cucumber, brassicas, radishes, marigold, borage, chervil, florence fennel, and leeks. Avoid parsley and celery.
Harvest: Harvest your lettuce when the head has grown 6–10″ tall, with tight leaves and a firm, but not too hard, texture. Cut just above soil line and leave the roots in place to allow your plant to grow more leaves, if desired. You can also pick individual leaves from the outer edges of the plant earlier, but don’t take more than 1/3 of the total plant. Try to harvest in the morning when leaves are moist and cool.
Storage: Store in the refrigerator for up to 1 week. Avoid storing lettuce in the same area as fruits such as bananas or apples: they release a ripening agent that causes your lettuce to go bad more quickly.
Fun Fact: Did you know that romaine lettuce can regrow from the root end once you have chopped off the leaves? It’s true! Simply cut the leaves about 2″ above the root end and place the remaining base in a glass of water. Keep the water fresh by changing it out every day for the next couple of weeks and you should see roots emerge and new leaves will start to sprout from the cut end. Talk about the power of plants!
Preserve: Due to its high water content, lettuce cannot be easily preserved and should be eaten fresh.
Prepare: Good for use in salads, sandwiches, smoothies, or even soups. Chop off the bottom of heads and separate individual leaves. Wash just before using for longest storage life.
Nutritional: A good source of vitamin(s) A, K, calcium, potassium, and manganese. Also contains good amounts of dietary fiber.
Medicinal: Historically, lettuce was cited as a veritable cure-all. Today, it has been shown to have high levels of beta-carotene. The antioxidant content of darker leaves may offer some protective benefits against disease.
Lettuce often gets pigeonholed as a salad or sandwich ingredient, but there is really so much more that can be done with this veggie! For instance, these Romaine Lettuce Veggie Wraps are both nutritious AND delicious!