Multileaf lettuce has transformed commercial lettuce production with its high yield, versatility, and consumer appeal. Explore the full range of multileaf varieties available from Paramount Seeds.

Introduction Romaine lettuce is one of the most popular and commercially important lettuce types for greenhouse and hydroponic production. Its upright growth habit, crisp texture, and strong consumer demand make it a natural fit for NFT channels, DWC systems, and vertical growing environments. But with so many varieties available, choosing the right one for your production system and market can be a challenge. At Paramount Seeds, we carry a comprehensive range of romaine varieties — from large full-size heads for foodservice and retail, to compact midi and mini types suited to living lettuce and single-serve markets. This guide walks you through our top 10 most popular romaine varieties to help you make the right choice. Understanding Romaine Types Romaine lettuce varieties for greenhouse production generally fall into three size categories, each suited to different markets and production systems: Full-size romaine: Large, upright heads (typically 300–600g) suited to foodservice, retail bags, and whole-head retail. These are the workhorses of commercial greenhouse romaine production. Midi romaine: Medium-sized heads (typically 150–300g) well-suited to single-serve retail, living lettuce, and premium fresh markets. Mini romaine: Small, compact heads (typically 80–150g) ideal for single-serve retail and living lettuce displays. Within each size category, varieties differ in tip burn tolerance, bolting resistance, head weight, and shelf life. Matching the right variety to your production system, climate, and market is the key to maximizing profitability. Top 10 Romaine Varieties for Greenhouse Production 1. Tacitus F1 (41-200) — Full-Size Our most popular romaine variety. Tacitus is a high-performing full-size romaine with exceptional head weight, outstanding uniformity, and excellent tip burn tolerance. It produces large, upright, well-blanched heads with crisp texture and excellent shelf life — making it the top choice for commercial greenhouse growers supplying foodservice and retail markets. Available in pelleted seed for precise, efficient seeding. Best for: Foodservice, retail bags, year-round production 2. Rabello F1 — Full-Size A strong-performing full-size romaine with excellent head uniformity and good tip burn tolerance. Rabello delivers consistent head weight and quality throughout the season, making it a reliable choice for commercial greenhouse production. Its attractive appearance and crisp texture are well-suited to retail and foodservice markets. Best for: Retail, foodservice 3. Solid Heart F1 — Full-Size A full-size romaine with a distinctive tightly blanched heart and excellent eating quality. Solid Heart is well-suited to whole-head retail and premium foodservice markets where heart quality and presentation are priorities. Available in untreated pelleted seed. Best for: Whole-head retail, premium foodservice 4. Monte Carlo F1 — Full-Size A reliable full-size romaine with good head weight, strong uniformity, and consistent performance across a range of growing conditions. Monte Carlo is a dependable choice for commercial greenhouse growers seeking a versatile, all-round romaine variety. Available in untreated pelleted seed. Best for: General greenhouse & hydroponic production 5. Gladius F1 (41-CO1089) — Full-Size A high-performing full-size romaine with excellent tip burn tolerance and strong plant vigor. Gladius delivers consistent head quality and uniformity throughout the season, making it a dependable choice for year-round greenhouse production. Best for: Year-round production, retail 6. Cosbee F1 — Full-Size A classic cos-type romaine with excellent head structure, crisp texture, and strong consumer appeal. Cosbee is well-suited to retail and foodservice markets and delivers reliable yields in greenhouse and hydroponic production systems. Best for: Retail, foodservice 7. Solid King F1 — Midi A midi romaine with a tightly blanched heart and excellent eating quality. Solid King is well-suited to single-serve retail and premium foodservice markets where heart quality and presentation are priorities. Available in untreated pelleted seed. Best for: Single-serve retail, premium foodservice 8. Sparx F1 — Full-Size A vigorous full-size romaine with excellent uniformity and strong tip burn tolerance. Sparx delivers consistent head weight and quality and is well-suited to high-density greenhouse and hydroponic production. Available in both pelleted and non-pelleted seed formats. Best for: High-density greenhouse & hydroponics 9. Elizium F1 — Full-Size A reliable full-size romaine with good head weight and consistent performance. Elizium is well-suited to commercial greenhouse production and delivers attractive, well-formed heads with good shelf life. Best for: Commercial greenhouse production 10. Cobain F1 — Midi Our most popular midi romaine. Cobain produces compact, well-formed heads with excellent uniformity and strong tip burn tolerance. It is well-suited to living lettuce and single-serve retail applications, delivering attractive, crisp heads with good shelf life. Best for: Living lettuce, single-serve retail Quick Comparison Variety Type Key Traits Best For Tacitus F1 (41-200) Full-size Top seller, excellent tip burn tolerance, outstanding uniformity Foodservice, retail bags, year-round production Rabello F1 Full-size Excellent uniformity, good tip burn tolerance Retail, foodservice Solid Heart F1 Full-size Tightly blanched heart, excellent eating quality Whole-head retail, premium foodservice Monte Carlo F1 Full-size Reliable, versatile, consistent performance General greenhouse & hydroponic production Gladius F1 (41-CO1089) Full-size Excellent tip burn tolerance, strong vigor Year-round production, retail Cosbee F1 Full-size Classic cos type, crisp texture, strong consumer appeal Retail, foodservice Solid King F1 Midi Tightly blanched heart, excellent eating quality Single-serve retail, premium foodservice Sparx F1 Full-size Strong tip burn tolerance, high-density production High-density greenhouse & hydroponics Elizium F1 Full-size Good head weight, consistent performance Commercial greenhouse Cobain F1 Midi Compact, excellent uniformity, tip burn tolerant Living lettuce, single-serve retail Production Tips for Greenhouse Romaine Seeding All Paramount Seeds romaine varieties are available in pelleted seed for precise, efficient seeding in plug trays. Sow into 128- or 200-cell plug trays using a well-draining seedling mix. Germination typically occurs within 3–5 days at 18–22°C (65–72°F). Transplanting Transplant at the 2–3 true leaf stage into NFT channels, DWC systems, or growing media. Standard spacing for full-size romaine in greenhouse systems: 20–25 cm in-row spacing (approximately 16–25 plants/m²). Temperature Romaine lettuce performs best at day temperatures of 18–22°C (65–72°F) and night temperatures of 14–18°C (57–65°F). Avoid temperatures above 25°C, which can cause tip burn and bolting. Supplemental cooling or shading is recommended during summer production. Tip Burn Management Tip burn is the most common quality issue in greenhouse romaine production, caused by calcium deficiency in rapidly growing inner leaves. Key management strategies include: Choose varieties with strong tip burn tolerance (Tacitus, Gladius, and Sparx are top performers). Maintain good air circulation within the canopy — use horizontal airflow fans to reduce boundary layer resistance. Avoid excessive nitrogen fertilization, which promotes rapid growth and increases tip burn risk. Maintain consistent irrigation and avoid large fluctuations in EC and moisture levels. Supplemental calcium foliar sprays can help in high-risk periods. Harvest Harvest when heads reach target weight and the inner leaves are well-blanched. Cut cleanly at the base and handle gently to avoid bruising. For living lettuce production (Cobain, Solid King), harvest with roots intact and package in clamshells or bags with the root ball. Final Thoughts For most commercial greenhouse operations, Tacitus F1 is our top recommendation — outstanding tip burn tolerance, excellent uniformity, and proven performance across a wide range of growing conditions. For heart-quality specialists, Solid Heart F1 is an excellent choice. For midi and living lettuce production, Cobain F1 and Solid King F1 deliver excellent results. Contact our team to discuss variety selection, seed availability, and trial options for your upcoming season. We’re here to help you grow with confidence.

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