How to Grow Cos Lettuce Cimarron
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Cos Lettuce Cimarron
Lactuca sativa var. longifolia
vegetableCimarron is a romaine (cos) lettuce variety known for its tall, upright growth habit and crisp, tender leaves with excellent flavor. This heat-tolerant cultivar maintains quality and slow bolting characteristics even in warm conditions, making it ideal for spring through fall gardening.
When should you plant Cos Lettuce Cimarron in your zone?
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Example Cos Lettuce Cimarron timeline · Pittsburgh, PA (Zone 6b)
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Plant Cos Lettuce Cimarron
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 Cimarron
Around Jun 11≈ 55 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Cos Lettuce Cimarron dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-10; performs exceptionally well in zones 5-9 with heat tolerance allowing extended season
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Get my Cos Lettuce Cimarron timeline →Growth Stages
Seedling
7-10 daysFirst true leaves emerge; small rosette with 2-4 leaves visible. Cotyledons (seed leaves) prominent initially.
Keep soil consistently moist. Provide bright light (12+ hours). Thin seedlings to prevent crowding. Maintain 65-70°F temperature.
Vegetative Growth
3-4 weeksRapid leaf production with 6-10 leaves forming a tight rosette. Upright growth habit becomes apparent; plant develops characteristic romaine structure.
Maintain consistent moisture and cool temperatures (65-75°F ideal). Apply balanced fertilizer every 2-3 weeks. Thin to final spacing. Mulch to retain moisture and cool soil.
Mature Head Formation
2-3 weeksLeaves reach full length (10-12 inches typical) with dense, upright head structure. Inner leaves are pale green/white. Plant appears compact and substantial.
Continue consistent watering. Monitor for bolting—Cimarron's heat tolerance helps, but temperatures above 75°F accelerate bolting. Light feeding if needed. Ensure adequate spacing for air circulation.
Harvest-Ready
Varies (1-2 weeks optimal window)Full-sized heads with crisp, tender leaves. Outer leaves darker green, inner leaves pale. Plant is dense and compact without flowering.
Begin harvesting outer leaves for cut-and-come-again method, or harvest entire head. Early morning harvest yields crispest leaves. Harvest before bolting occurs.
Bolting
5-7 days (progression accelerates with heat)Central stem elongates and flowers begin to form. Leaves become bitter and fibrous. Plant transitions to seed production.
Once bolting starts, quality declines rapidly. Harvest entire plant immediately if not yet harvested. Remove bolting plants to redirect garden resources.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Spray with neem oil or insecticidal soap. Introduce ladybugs or lacewings. Reflective mulch deters aphids. Strong water spray dislodges pests.
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Hand-pick at dusk/night. Create barriers with crushed eggshells or diatomaceous earth. Beer traps. Remove debris and mulch hiding spots. Copper tape around planters.
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Prevent with crop rotation. Avoid planting in infected soil. Use floating row covers over young plants. Remove affected plants immediately.
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Yellow sticky traps. Neem oil or insecticidal soap spray. Encourage parasitic wasps. Remove heavily infested leaves.
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Hand-pick. Bacillus thuringiensis (Bt) spray. Floating row covers. Encourage birds and parasitic wasps.
Uses
Fresh Salads & Wraps
CulinaryCimarron's crisp, tender leaves and mild flavor make it ideal for fresh salads, Caesar salad, lettuce wraps, and grain bowls. The upright structure makes individual leaves easy to separate and use. [source]
Cooking & Braising
CulinaryUnlike delicate lettuces, romaine varieties like Cimarron can be lightly cooked, grilled, or braised, maintaining structure and developing subtle sweetness when heat-treated. [source]
Nutritional & Antioxidant Content
MedicinalRomaine lettuce is rich in vitamins K, A, and C, folate, and antioxidants like quercetin and kaempferol. These compounds support bone health, immune function, and reduce inflammation. [source]
Digestive & Wellness Support
HouseholdThe fiber content and light digestibility make romaine lettuce a gentle addition to wellness routines. Historically used in herbal preparations for mild sedative properties (lactucarium compound). [source]
Pollinator & Beneficial Insect Support
WildlifeIf allowed to bolt and flower, Cimarron provides nectar and pollen for bees, butterflies, and beneficial insects critical to garden ecosystem health. [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 plant has 8+ leaves (cut-and-come-again method) for extended harvest. For full head harvest, cut at soil line in early morning when leaves are crisp and turgid. Heads are typically ready 55-70 days after planting. Harvest before bolting; Cimarron is heat-tolerant but will eventually bolt in sustained high temperatures. Wash and dry thoroughly. Store in perforated plastic bags in refrigerator crisper drawer for up to 2 weeks.
Fun Facts
- 🌱 Cimarron is Spanish for 'wild' or 'untamed,' reflecting this variety's robust heat tolerance and resilient growing characteristics compared to other romaine cultivars.
- 🌱 Romaine lettuce gets its name from its historical popularity in Rome, where it was cultivated for centuries; it remains a cornerstone of Mediterranean cuisine.
- 🌱 Cos and romaine are the same plant—'cos' is the British/Mediterranean term, while 'romaine' is the North American standard; both refer to Lactuca sativa var. longifolia.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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