How to Grow Cos Lettuce Jericho
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Cos Lettuce Jericho
Lactuca sativa var. longifolia
vegetableCos Lettuce Jericho is a heat-tolerant romaine lettuce variety known for its upright, elongated head with crisp, tender leaves and excellent flavor. It's a specialty cultivar bred specifically for hot climates and summer growing. This variety produces dense heads that are ideal for both fresh consumption and culinary applications.
When should you plant Cos Lettuce Jericho in your zone?
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Example Cos Lettuce Jericho timeline · Pittsburgh, PA (Zone 6b)
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Plant Cos Lettuce Jericho
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Cos Lettuce Jericho
Around Jun 6≈ 50 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Cos Lettuce Jericho dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Performs exceptionally well in zones 6-9, especially in warm and hot climates where heat tolerance is essential
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Get my Cos Lettuce Jericho timeline →Growth Stages
Seedling
10-14 daysTiny cotyledons emerge, followed by first true leaves. Plants are delicate and require consistent moisture.
Keep soil consistently moist. Provide bottom heat (65-70°F) for faster germination. Thin seedlings to prevent damping-off disease.
Vegetative Growth
20-30 daysRapid leaf production as plants establish. Leaves are tender and bright green, forming a rosette pattern before heading begins.
Maintain consistent watering and weekly feeding with diluted liquid fertilizer. Ensure adequate light to prevent leggy plants. Begin afternoon shade if temperatures exceed 80°F.
Head Formation
15-20 daysCentral leaves begin to curve inward and elongate vertically. The characteristic upright romaine head shape becomes evident.
Continue consistent moisture and nutrition. Monitor for aphids and other pests. Maintain shade cloth if daytime temps exceed 85°F to prevent tip burn and bolting.
Maturity & Readiness
5-10 days optimal harvest windowFirm, dense head with crisp outer and tender inner leaves. Head feels solid when gently squeezed. Leaves are medium green with excellent texture.
Begin harvesting outer leaves or cut entire head. Can be harvested over time as cut-and-come-again. Keep harvesting to encourage continued production and prevent bolting.
Senescence/Bolting
Begins 65+ days after planting in hot conditionsIf left unharvested, the central stem elongates and flower buds form. Leaves become bitter and texture deteriorates.
Harvest immediately when head feels firm to avoid bolting. Bolting is triggered by heat and day length; heat-tolerant varieties like Jericho resist this longer than standard romaine.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Spray with strong water jet; use insecticidal soap or neem oil; introduce ladybugs; reflective mulches deter infestations
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Remove affected plants immediately; control aphid vectors; use resistant varieties; maintain weed-free area; disinfect tools
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and
(Gastropoda)
Hand-pick at night; use copper tape barriers; beer traps; food-grade diatomaceous earth; encourage ground beetles
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Yellow sticky traps; spray insecticidal soap or neem oil; reflective mulch; avoid excessive nitrogen fertilizer
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Ensure proper air circulation; avoid overhead watering; remove infected leaves; apply sulfur-based fungicide; plant in well-drained soil
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Rotate crops; solarize soil; use reflective mulches; grow under row covers early season; avoid excessive irrigation
Uses
Fresh Salads & Wraps
CulinaryCos Lettuce Jericho's crisp texture and mild, sweet flavor make it ideal for Caesar salads, green salads, and lettuce wraps. The sturdy leaves hold up well to dressings without wilting. [source]
Cooking & Grilling
CulinaryThe firm head structure allows for grilling whole romaine halves or using in cooked dishes like sautéed greens. Heat-tolerant Jericho variety maintains texture through gentle cooking. [source]
Nutritional & Anti-inflammatory Benefits
MedicinalRomaine lettuce is rich in vitamins K, A, and C, plus folate and manganese. Contains compounds with mild sedative and anti-inflammatory properties traditionally used in herbal medicine. [source]
Juice & Smoothie Base
HouseholdTender leaves of Cos Lettuce Jericho blend smoothly into fresh juices and green smoothies, providing hydration and micronutrients with mild flavor that doesn't overpower other ingredients. [source]
Beneficial Insect Support
WildlifeIf allowed to bolt and flower, Cos Lettuce produces yellow blooms that attract pollinators and beneficial insects including hoverflies and parasitic wasps that control garden pests. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Begin harvesting outer leaves when plants are 4-6 inches tall for tender baby lettuce, or wait for full head maturity (50-65 days). Cut entire head at soil level with a sharp knife, or use scissors for cut-and-come-again harvesting of outer leaves. Harvest in early morning for maximum crispness and water content. Jericho is heat-tolerant but should still be harvested before peak summer heat (above 90°F) for best quality. Refrigerate immediately after harvest in damp towels; use within 10-14 days.
Fun Facts
- 🌱 Cos Lettuce Jericho was specifically bred to thrive in the hot, arid climate of the Middle East and Mediterranean regions, making it one of the most heat-tolerant romaine varieties available—it can produce quality heads in temperatures that cause other lettuce to bolt.
- 🌱 Romaine lettuce gets its name from its association with Rome; ancient Romans documented its cultivation and nutritional value over 2,000 years ago, though the modern cos/romaine type developed in the Mediterranean region.
- 🌱 The upright, elongated head shape of romaine lettuce is distinct from butterhead varieties and is specifically selected because the inner leaves naturally blanch (turn lighter and more tender) due to reduced light exposure within the tight head structure.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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