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Green Leaf Lettuce Information

Green leaf lettuce or leaf lettuce (crispa) is an omnibus name for a handful of loose leaf gourmet lettuce varieties which are members of the Asteraceae family. Leaf lettuce is a vegetable which grows upright in an elongated manner and does not form a head or bulb. It emanates from a single stock and has a wide curly loose top characterized by attractive generally bright green leaves. Some leaf lettuces are cut-and-come-again varieties.

The other lettuce types which are not leaf lettuce are head lettuce (capitata), romaine lettuce (longifolia) and celtuce lettuce (augustana).

Where to Find Leaf Lettuce Seed

Green leaf lettuce seeds of the different varieties can be found online and offline at gardening stores. Many commercially available leaf lettuce seeds can be planted immediately or stored in a seed safe for later use. Furthermore, many varieties are suitable for cultivation in USDA Zones: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12.

The Origins of Green Leaf Lettuce

Lettuce is native to eastern Mediterranean & Western Asia. It is scientifically known as Lactuca sativa. The cultivation of lettuce in general has been traced back to 4500 B.C. The vegetable was grown by the Egyptians, Greeks and Romans. It is believed that the Romans introduced lettuce to western Europe. In addition, the Caribbean is said to have become aware of lettuce courtesy of Columbus.

Over a period of 200 years, lettuce cultivars spread to North and South America. Throughout the history of lettuce, efforts were made in various places to develop different cultivars. For example, in the 1600s European horticulturalists were developing curled leaf lettuces. More lettuces with various leaf styles were developed in France, The Netherlands and Italy. Brown Dutch is one of the oldest surviving heirloom lettuce.

The development of lettuce overtime made it more palatable, having started as a bitter plant whose seeds were used to produce oil. This explains the bitterness that is still found in some lettuce varieties to this day. The different green leaf lettuce cultivars are a product of a protracted history of breeding.

General Lettuce Characteristics (Video)

This video by North Carolina State University (NCSA) gives a description of Lactuca sativa (lettuce).

Green Leaf Lettuce Varieties

There are over a dozen green leaf lettuce varieties. The following are some of the well known and loved leaf lettuce cultivars.

Coral Lettuce

Picture of coral lettuce, a type of loose leaf lettuce.
Coral Lettuce

Coral lettuce is named as such due to its resemblance to corals of the marine ecosystems.  It has frilly curls. Coral lettuce is also known by its alternative names Lollo Rosso, or Lollo Bionda. Coral is a loose leaf cultivar which typically can be bright green, deep red or speckled.

Frisée Lettuce

Picture of Frisée lettuce, a type of green leaf lettuce.
Frisée lettuce

Frisée lettuce has a close family relationship with Escarole lettuce. It is alternatively known as curly endive. Frisée lettuce can be described as having long, narrow and curly leaves. For the most part, the lettuce had roots in Europe before being introduced to the United States in the 1990s. It has since gained popularity as a gourmet leafy green.

Frillice Lettuce

Picture showing Frillice lettuce, a type of leaf lettuce.
Frillice Lettuce

Frillice lettuce is a cross breed between iceberg lettuce and curly endive. The breed produced leaves that are thick and green as those of the iceberg and tops that look like the curly endive in crinkles. This cultivar is sometimes described as a curly Iceberg due to the looks.

Mizuna Lettuce

Picture showing Mizuna Lettuce which is often referred to as green leaf lettuce although this is strictly not the case.
Mizuna Lettuce

Although it widely passes in general talk for a lettuce, the Mizuna in fact belongs to the Brassicaceae or mustard family. It is alternatively referred to as the Japanese mustard greens. There are over sixteen different varieties of Mizuna. Just like most green leaf lettuces, the Mizuna grows from a central stalk with long stems with dark green leaves.

Wintergreen Cut Lettuce

Picture showing Wintergreen Cut Lettuce a type of green leaf lettuce cultivar.
Wintergreen Cut Lettuce

Wintergreen Cut lettuce is an example of a cut-and-come-again lettuce variety. The leaves grow back all season each time they are harvested. This is a European (Switzerland) bred cultivar recognizable by its light green and rounded leaves.

Italienischer Lettuce

Picture showing Italienischer lettuce.
Italienischer Lettuce

Italienischer lettuce is a sweet lettuce which is only turned to bitterness by the summer’s heat. This lettuce can be described as bushy, yet upright and tall in stature. It grows to about 45 cm or 18 inches which makes it stand out among most known lettuce varieties.

Salad Bowl Lettuce

Picture showing popular salad bowl lettuce a green leaf lettuce cultivar.
Salad Bowl Lettuce

Salad Bowl lettuce is a special loose-leafed lettuce cultivar. It does not get bitter in hot weather due to its heat tolerance. It is a suitable variety for the home garden. The salad bowl is recognizable by its large, lime-green rosettes of delicate tender leaves. The variety resists bolting for a long time in hot summer weather.

Cress Lettuce

Picture showing cress lettuce.
Cress Lettuce. Harvesttotable.com

Cress lettuce is also known as watercress, upland cress, curly cress or land cress. The mature watercress is identified by its small green leaves and a tough, fibrous stem. For tender stems, look for baby cress lettuce. The waterclass is not really a lettuce. It belongs to the Brassicaceae family where cabbage, kale, and mustard greens are found.

Leaf Lettuce Taste & Flavor

Green leaf lettuce represents a variety of lettuce types. Taste and flavor varies depending on the specific lettuce involved. For example, Coral lettuce has a sweet flavor while  Frisée lettuce has a mildly bitter and a bit of a peppery taste. Frisée lettuce has been described as having a slightly nutty flavor. 

Broadly speaking, green leaf lettuce offers a mildly sweet or semi-bitter flavor. The maturing leaves tend to have a bitter taste compared to the younger tender leaves. The table below provides a summary of flavors and taste associated with a variety of leaf lettuces.

Leaf Lettuce Flavors (Table)

Leaf LettuceTaste/Flavor
Coral LettuceSweet flavour
Frisée LettuceMildly bitter, slightly peppery taste, Nutty flavor
Frillice LettuceNeutral, mild and slightly bitter flavor.
MizunaPeppery taste, slightly bitter.
Wintergreen Cut LettuceSweet & tender.
Italienischer LettuceSweet & crisp.
Salad Bowl LettuceMild and subtle flavor.
Butter Lettuce Mild, sweet flavour and delicate texture.
Cress LettucePeppery taste.
Mache LettuceMild, herbal, and nutty flavor.

Green Leaf Lettuce Health Benefits

Lettuce known as Lactuca sativa is in general terms very nutritious. It appears all lettuce cultivars deliver a good punch of nutrients, in general. Lettuces are a good source of vitamins A, K, C, folate, manganese and chromium. Detailed health benefits of lettuce will vary depending on the specific variety one consumes. 

The following is a list of health benefits associated with lettuce.

  • Hydration – due to high (95%) water content in lettuce.
  • Bone strength – credited to Vitamin K in lettuce which also reduces risk of bone fracture.
  • Improved sleep – mainly observed following the use of lettuce extracts
  • Improved vision – credited to the Vitamin A in lettuce
  • Aids in weight loss – most as a result of the low calories in lettuce
  • Anti-cancer properties – lettuce has been observed to have potential anti-tumor benefits
  • Improves glucose metabolism – glucose metabolism is related to diabetes according to research.

Loose Leaf Lettuce Culinary Applications

Green leaf lettuce is used in a variety of recipes as a raw ingredient. The lettuce is mostly applied in salads to add color and flavor. Respective leaf lettuce cultivars introduce different flavors and taste. 

Skilled cooks carefully harness the different flavors to produce highly flavorful dishes whose ingredients are in sync. See below about respective green leaf lettuce flavors.

Loose leaf lettuce can be shredded or cut and used in tacos, sandwiches, and on burgers. Furthermore, the leaves may be used as edible food liners for serving other foods such as finger foods and salads. 

The following are some recipes made using green leaf lettuce.

Salad Bowl Lettuce, Cherry Tomato & Cucumber Salad

This is a traditional Eastern European garden salad with a slight twist. It contains no garlic and is made using any favorite green leaf lettuce. 

Picture of Salad Bowl Lettuce, Cherry Tomato & Cucumber Salad made using green leaf lettuce
Credit: Ifoodreal.com

Ingredients

  • Cucumbers (peeled)

  • Cherry tomatoes

  • Lettuce (any green leaf lettuce)

  • Dill

  • Onion

  • Olive Oil

  • Pepper

  • Salt

Directions

  • Wash all vegetables. Chop and add to a large bowl.
  • Add seasonings by adding all oil and all seasonings to the bowl
  • Next step, gently mix everything until properly combined.
  • Serve with favorite roast meat and/or with pies
  •  Leave to sit for 30 to 60 minutes before serving.

Quick and Easy Lettuce Salad Recipe (Video)

In this video, a slightly different loose leaf salad is made using lettuce, cucumber, tomatoes, onions, lemon juice, olive oil, salt and pepper.

How to Grow Green Leaf Lettuce

Lettuce is easy to grow. Loose leaf lettuce is even easier to grow compared to the other head lettuce types. Head varieties have more disease problems and take longer to mature. Leaf lettuce is attractive to grow because it does not require huge space. It can easily grow in containers. Depending on the cultivar, green leaf lettuce is ready for harvest in about 45 to 50 days or 6-7 weeks vs head lettuce’s 10 to 11 weeks.

Lettuce thrives in cool weather. This makes it a cool weather crop. It is challenging to grow in summer conditions when disease pressure increases. Hot weather conditions also induce bolting in some cultivars. Lettuce is a recommended companion crop for tomatoes. It can be planted alongside or among tomato plants.

Jump to our in depth feature on How to Grow Tomatoes.

Leaf Lettuce Growing Soil

Lettuce adapts to many types of soil as long as there is good drainage. However, loose leaf lettuce is best grown in well drained loamy soils which allow roots to go as deep as 600mm or 23 inches. To achieve this, the soil is well prepared before planting. Furthermore, the soil is ripped, ploughed and then disced as needed. This is mostly the case when green leaf lettuce is grown at scale. The recommended soil pH is between 6.0 and 7.0. Lettuce is sensitive to low pH.

Planting Green Leaf Lettuce

Green leaf lettuce is planted during the mild weather of early spring and fall. The plants are situated in a location that gets an abundance of sunlight. Lettuce seedlings are spaced between 15cm and 45cm apart 6 to 18 inches apart. The crop can be planted as seeds or as already germinated seedlings. Seeds are planted 6mm to 13mm deep (1/4 inch to 1/2 inch). Lettuce has a light requirement for germination. Seeds should not be planted too deep.

Lettuce germinates at a temperature range of between 15 and 20ºC. Higher temperatures of above 25ºC will jeopardize germination of lettuce seeds. Under hot temperatures, lettuce seeds may suffer thermodormancy. They enter a state of dormancy and consequently fail to germinate.

For continuous supply, lettuce is planted every 10 to 14 days. 

Leaf Lettuce Fertilizer

Once planted in the correct soil, lettuce is generally a low-maintenance crop. It will require side application of fertilizers as the season progresses. This is more so the case with cut-and-come-again lettuce varieties that need to regrow after each leaf harvest. 

Once the loose leaf lettuce has germinated, the crop is fed with a balanced water soluble or granular fertilizer of NPK 10-10-10 or a 5-5-5. NPK standards for nitrogen, phosphate, and potassium.

Compost and manure are ideal organic materials to boost the nutrition of the soil. These organic materials also improve soil drainage. Fish emulsion is also a good fertilizer. However, some growers complain of residual smell from its use on lettuce.

Watering Leaf Lettuce

Water is an essential requirement for lettuce seed germination and their subsequent establishment. Apply light watering frequently. This technique causes the leaves to rapidly develop leading to high quality lettuce. Seasoned growers water the crop early morning allowing the leaves enough time to dry from leaf wetness. This reduces risk or limits foliar diseases.

To avoid diseases, soft growth and burning (scalding) of the leaf margins, lettuce should not be overwatered. A watering program of about twice a week, or once every four or five days is ideal.

Harvesting Leaf Lettuce

When to harvest green leaf lettuce is essentially a grower’s call. Lettuce is good to harvest and use even as microgreens. However, for mature leaf lettuce, harvest can be done whenever the leaves are big enough to use.

Depending on variety, at full maturity, green leaf lettuce has a maximum weight of between 170g and 340g. Seasoned growers use a technique of harvesting from every other plant at ground level creating room for remaining plants to grow. This is also referred to as thinning.

The best time to harvest lettuce is early morning. This takes advantage of cool morning temperatures. Furthermore, lettuce should not be harvested when wet or following some rains. The wet foliage is susceptible to rotting.

Storing Leaf Lettuce 

Lettuce is a highly perishable crop. Immediately after harvest, store in a cool place or refrigerate. In a home setting, lettuce is placed in the crisper drawer of the refrigerator. Depending on preference or application, the harvested lettuce can be chopped up and stored as a pre packaged salad mix.

Loose leaf lettuce can be stored for up to four weeks if properly harvested and bagged. Bagging wet lettuce reduces the shelf life hence the importance of harvesting and packaging it dry.

In addition, lettuce should be stored apart from certain fruits such as apricots, avocados, apples, bananas and pears. These fruits release a natural and odorless gas called ethylene which causes lettuce to wilt, spot or go bad. lettuce typically turn yellow when exposed to ethylene.

Green Leaf Lettuce Common Problems

Picture showing loose leaf lettuce affected by tipburn.
Lettuce Tipburn

Tipburn is a common problem that causes lettuce to die at the edges of the leaves. This is a physiological condition associated with calcium deficiency in lettuce. It occurs when the plant is unable to supply enough calcium to rapidly growing leaves. The brown leaf tissue can be clipped off and the remainder of the leaf used.

Light watering and liming the soil is used as prevention of the development of tipburn. Liming increases pH which is beneficial to the prevention of the condition. Furthermore, there are certain cultivars that are resistant to tipburn.

Other green leaf lettuce problems include bitterness due to high temperatures or a lack of soil moisture. Lettuce leaves are also susceptible to rotting due to soil and moisture on the leaves.

The following tables have some of the major diseases and pests affecting lettuce.

Common Leaf Lettuce Diseases (Table)

DiseaseDescription
Botrytis crown rotBrownish-gray to brownish-orange looking soft wet rot affecting older leaves in contact with soil
Downy Mildew-Bremia Occurs and spreads in high humidity and cool temperatures. Appears as light green to yellow angular spots on the upper surfaces of leaves.
Fusarium wiltAttacks roots causing severe stunting. leads to leaf yellowing and wilting.
Powdery MildewFungus that appears as light grey or white powdery spots on affected leaves.
Lettuce Big Vein Associated VirusAffected plants show leaf distortion and ruffling.
Lettuce Mosaic VirusSpread through seeds and plant to plant. Causes leaf distortions and leaf colour anomalies.
Corky RootSevere when soil temperatures are warmer. Disease severity increased by high nitrate levels. Above ground symptoms are wilting, stunting, poor & uneven growth
Pythium uncinulatumSoil borne disease. Above ground causes wilting of leaves, yellowing, browning and death
RhizoctoniaCaused by fungus which attacks older leaves in contact with soil. Leaves develop brown lesions
SclerotiniaFungal disease affecting the steam. Leaves wilt and turn gray-green before turning brown, curling and dying.
Tip Burn Caused by bacteria resulting in severe rot on lettuce leaves and head
ErwiniaCaused by bacteria resulting in severe rot on lettuce leaves and head

Common Leaf Lettuce Pests (Table)

PestDescription
Aphids-Nasonovia Also known as Lettuce Aphid, a severe pest which colonizes lettuce inner leaves.
Cut wormA worm that cuts seedlings off at or just below the soil line. Also bores into outer lettuce leaves.
White FlyTiny white flies that suck juices from lettuce leaves spreading viral diseases. Found mostly on the undersides of leaves.
ThripsTiny pests that puncture lettuce leaves and suck the plant's sap. Damaged leaves show a silvery appearance that eventually turns to brown scarring.
American BollwormLarvae penetrate the bottom of leaves and eat their way into the heads of lettuces.

Conclusion

The history of lettuce goes back to 4500 B.C when it was introduced by the Europeans. Green leaf lettuce is a headless type of lettuce that is easy to grow and maintain. It is a common produce that can be grown in small spaces and even containers. Leaf lettuce produces upright leaves with frills in many varieties. The different loose leaf lettuce varieties carry their own different flavors and are mostly consumed raw. This is a bonus for various lettuce culinary applications. Green leaf lettuce remains one of the most popular ingredients used in green salads all across the world.

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