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A healthy Romaine cos lettuce with tall upright dark-green leaves in a sunny garden

How to Grow Romaine Lettuce From Seed

By Maxim Kaufman — Founder & CEO, Organo Republic

Updated July 2026

Romaine, also called cos, is the tall, upright lettuce behind every Caesar salad, with sturdy dark-green leaves and a sweet, crunchy central rib. It is one of the more forgiving heading lettuces, tolerating a little more warmth than iceberg and standing well in the garden. Here is what makes this variety special and how to get the best from it.

This is the quick guide to Romaine. For the full step-by-step on starting seeds, sowing, feeding, and troubleshooting lettuce, see our complete guide to growing lettuce from seed.

Quick start

Sow seed about an eighth of an inch deep, barely covered, since lettuce needs light to sprout. Thin plants to 8 to 10 inches apart so the tall heads have room. Romaine forms sturdy, upright heads in about 65 to 70 days. Harvest by cutting the whole head at the base once it is full and crisp, or pick outer leaves as you go.

Best tip

Romaine, also called cos, grows tall and upright with sturdy, crisp leaves and a sweet, crunchy rib. It is one of the more forgiving heading lettuces, tolerating a bit more warmth than iceberg and standing well in the garden. Sow it shallow, keep it evenly watered, and give it room to grow upright. For the crispest hearts, let the head fill in fully before you cut it at the base.

At a glance

Botanical nameLactuca sativa

Plant typeCool-season annual (romaine/cos)

USDA zones2 to 11 (grown as an annual)

SunFull sun to part shade

Days to maturity65 to 70 days

Height8 to 12 inches

Spacing8 to 10 inches apart

WaterEven and steady; keep moist

Uses

Romaine is the sturdy, upright lettuce behind every Caesar salad, with tall, crisp, dark-green leaves and a sweet, crunchy central rib. It holds up beautifully to dressing, grills wonderfully into charred wedges, and adds reliable crunch to sandwiches and wraps. The whole head can be cut at once, or you can pick outer leaves as you go.

Frequently asked questions

How long does Romaine lettuce take to grow?

Romaine forms full, upright heads in about 65 to 70 days from sowing, though you can harvest outer leaves earlier. It is one of the more dependable heading types for home gardens.

Is Romaine lettuce heat-tolerant?

Romaine handles warmth better than iceberg and stands well in the garden, but it is still a cool-season crop. In hot regions, grow it in spring and fall, give afternoon shade, and keep the water steady to prevent bitterness and bolting.

What does Romaine lettuce taste like?

Romaine has crisp, dark-green leaves with a sweet, mild flavor and a signature crunchy central rib. That sturdy texture is why it is the classic lettuce for Caesar salads and grilling.

How do I harvest Romaine lettuce?

Cut the whole upright head at the base once it feels full and crisp, usually around 65 to 70 days, or pick outer leaves for a cut-and-come-again harvest. Morning is the best time for the crispest leaves.

Ready to grow your own? Romaine is one of the varieties in our lettuce and salad greens pack, so you can grow tall crisp heads alongside a whole salad garden. For the full step-by-step, see our complete lettuce growing guide linked at the top of this page.

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Want more lettuce? These value packs pair Romaine with other varieties:

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Lettuce & Greens Seeds Variety Pack – Non-GMO Heirloom22 lettuce & greensAn even bigger salad collection — 22 lettuces and greens for months of fresh leaves in every color and texture.

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By Maxim Kaufman — Founder & CEO, Organo Republic

Maxim founded Organo Republic in 2017 and personally selects, tests, and grows the heirloom, non-GMO varieties the company offers. Under his leadership, Organo Republic was named Agri Business Review’s Top Non-GMO Seed Variety Solution 2026.