500+ Parris Island Cos Romaine Lettuce Seeds

Parris Island Cos Romaine Lettuce Seeds (Lactuca sativa var. longifolia) produce tall, upright heads with crisp, dark green outer leaves and tender, creamy-white hearts. This dependable open-pollinated romaine variety develops uniform heads approximately 10–12 inches tall and is known for its sweet, refreshing flavor, crunchy ribs, and moderate resistance to bolting. The leaves are excellent for Caesar salads, sandwiches, wraps, burgers, fresh garnishes, and everyday garden salads.

Planting Season

Best planted in: Early Spring & Late Summer to Fall (Cool-Season Crop)

Sow seeds in early spring, approximately 2–3 weeks before the final expected frost, or as soon as the soil can be worked. For a fall harvest, sow in late summer after the hottest weather begins to pass.

Parris Island Cos grows best in cool conditions around 60–70°F (16–21°C). Although it tolerates warmth better than many lettuce varieties, prolonged temperatures above 75–80°F (24–27°C) can cause bitter leaves, poor germination, and premature bolting.

How to Grow Parris Island Cos Romaine Lettuce Seeds

Sow seeds directly outdoors or start them indoors approximately 3–4 weeks before transplanting.

Choose a location receiving 5–6 hours or more of direct sunlight each day. Provide light afternoon shade when growing during warmer weather.

Grow in fertile, loose, moisture-retentive, well-drained soil enriched with compost or aged organic matter.

Sow seeds approximately ⅛–¼ inch deep and cover them lightly with fine soil. Lettuce seeds should not be planted too deeply.

For direct sowing, plant seeds approximately 1 inch apart in rows spaced 12–18 inches apart.

Thin seedlings to approximately 8–12 inches apart for full-sized romaine heads. Plants may be spaced 4–6 inches apart when growing smaller heads or harvesting young leaves.

Keep the soil surface consistently moist but not waterlogged during germination.

Maintain soil temperatures around 55–70°F (13–21°C) for the best germination. Soil temperatures above approximately 80°F (27°C) may cause lettuce seeds to become temporarily dormant.

Seeds typically germinate within approximately 4–10 days under suitable conditions.

When starting indoors, sow 1–2 seeds per cell and provide bright light immediately after germination.

Transplant seedlings after they develop 3–4 true leaves. Harden them gradually for approximately one week before planting outdoors.

For continuous harvests, sow another small planting every 10–14 days while temperatures remain cool.

How to Care for Parris Island Cos Romaine Lettuce Plants

Water regularly and keep the soil evenly moist throughout the growing season. Lettuce has shallow roots and may develop tough, bitter leaves when allowed to dry out.

Provide approximately 1–2 inches of water per week, depending on rainfall, temperature, and soil type.

Water near the base of the plants early in the day. Avoid repeatedly soaking the leaves and central head, especially during cool or humid weather.

Prepare the soil with compost before planting. Apply a light, balanced fertilizer after thinning or transplanting if growth is slow or the leaves appear pale.

Avoid excessive fertilizer, as overly rapid growth can produce soft, weak leaves.

Apply a light layer of clean organic mulch to conserve moisture, suppress weeds, and keep the soil cool.

Remove weeds carefully with shallow cultivation to avoid damaging the plants’ delicate roots.

Use shade cloth during unexpectedly hot weather to keep the plants cooler and delay bolting.

Inspect plants regularly for aphids, slugs, snails, cutworms, and caterpillars.

Harvest individual outer leaves whenever they reach a useful size, leaving the central growing point intact for continued production.

For full heads, harvest when the plants are approximately 10–12 inches tall and the leaves have formed a firm, upright rosette. Cut the entire head near soil level early in the morning for the crispest texture.

Parris Island Cos Romaine Lettuce typically matures within approximately 65–70 days, although tender baby leaves can be harvested much earlier.

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