Lettuce

Basic Information

Seed Number

155

Seed Name

Lettuce

Variety

Parris Island Cos (Romaine)

Category

Vegetable

Plant Family

Asteraceae

Plant Type

Romaine lettuce (Lactuca sativa)

Planting Method

Direct Sow or Transplant

Seed Status

In Seed Bank

Created

2026-08-14 00:50:34

Updated

2026-08-19 15:35:29

Planting Information

Start Planting Date

Mar 10

Last Recommended Planting Date

Sep 1

Plantable Months

March, April, May, July, August, September

Indoor Start

Mar 10 – Apr 1

Direct Sow

Apr 1 – Aug 31

Transplant

Apr 15 – Sep 1

Indoor Start Weeks Before Frost

8 weeks

Transplant Weeks After Frost

Not recorded

Germination Days

7–10 days

Harvest/Maturity

28–55 days 28 days baby leaf; 55 days full size

Succession Planting

14 days

Growing Conditions

Ideal Soil Temperature

40-70°F

Planting Depth

1/4 in

Plant Spacing

8-12 in

Row Spacing

12-18 in

Thin-To Spacing

12 in

Sun Requirements

Full sun to partial shade

Water Needs

Maintain consistent moisture; approximately 1 in/week

Soil Preference

Fertile, well-drained soil rich in organic matter; approximately pH 6.0-7.0

Minimum Container Size

8-10 in deep

Plant Height

Not recorded

Perennial/Biennial Status

Annual

Container Friendly

Yes

Trellis/Support Needed

No

Frost Tolerant

Yes

Heat Tolerant

Yes

Drought Tolerant

No

Pollinator Friendly

No

Medicinal

No

Garden Uses

Companion Planting

Storage

Seed Source/Brand

Botanical Interests; Fedco Seeds; UMN Extension

Packet Year

Not recorded

Quantity Notes

Not recorded

Purchase Date

Not recorded

Expiration Year

Not recorded

Storage Box

Not recorded

Container

Not recorded

Envelope

Not recorded

Row

Not recorded

Slot

Not recorded

Storage Notes

Not recorded

Notes

Original Planting Method: Direct sow or start indoors for transplanting. Space farther apart for full romaine heads; can also harvest young.
Original Start Planting Date: Mar 20 – Mar 25
Original Last Suggested Planting Date: ~Aug 5 full heads; ~Aug 25 baby greens
Outdoor / Direct Sow / Transplant Window: Spring sow/transplant ~Mar 25 – May 5. Fall sow ~Jul 20 – Aug 5 for full heads; later Aug sowing better for baby leaf.
Days to Harvest / Bloom: ~21 days baby leaf; ~65–70 days full heads
Container Friendly: Yes; ~8+ in deep container
Pollinator Friendly: Low normally; bolted flowers can attract small pollinators
Medicinal / Herbal Use: Culinary leafy green
Succession / Reusable Notes: Sow every 1–2 weeks in spring and again during late-summer/fall planting window.
Zone 6B Notes: In Zone 6B aim for early spring and late-summer plantings. Full fall heads need earlier sowing than loose-leaf lettuce because this variety matures slower.
Companion Plants: Carrots, peas, radishes, onions, taller crops providing some afternoon shade
Avoid Planting Near / Watch Outs: Heat can cause bolting/bitter leaves; very warm soil can reduce germination. Keep moisture steady to reduce stress/tipburn.
Sources: Botanical Interests: https://www.botanicalinterests.com/products/parris-island-cos-romaine-lettuce-seeds | Fedco Seeds: https://fedcoseeds.com/seeds/parris-island-cos-romaine-lettuce-2879 | UMN Extension: https://extension.umn.edu/vegetables/growing-lettuce-endive-and-radicchio

[[RESEARCH ENRICHMENT START]]
Zone 6B: Parris Island Cos is suitable for spring and fall crops and has better heat tolerance than many lettuce varieties, but quality is still best under cool conditions.
Germination: Direct sow as soon as the soil is workable or start transplants indoors. Lettuce seed should remain shallow and consistently moist.
Harvest: Harvest baby leaves from about 28 days or allow plants to form upright full-size romaine heads around 55 days.
Seed Saving: Allow selected plants to bolt, flower and produce mature dry seed heads. Lettuce is primarily self-pollinating.
Special Care: Parris Island Cos was developed around 1950 and is known for upright medium-green leaves, crisp ribs and a buttery-green heart.
Research Source: Botanical Interests — https://www.botanicalinterests.com/products/parris-island-cos-romaine-lettuce-seeds — Parris Island Cos identity, romaine type, historical origin and upright leaf characteristics
Research Source: High Mowing Organic Seeds — https://www.highmowingseeds.com/organic-non-gmo-parris-island-cos-lettuce.html — 28-day baby-leaf and 55-day full-size maturity
Research Source: Ferry-Morse — https://ferrymorse.com/products/organic-lettuce-parris-island — 1/4-inch sowing depth and approximately 12-inch final thinning
[[RESEARCH ENRICHMENT END]]