How to Grow Romaine
Romaine At a Glance
Difficulty
Moderate
Category
Vegetable
Sun Exposure
Full Sun, Partial Sun
Frost Tolerance
Frost Hardy
Cold Hardiness
Survives to -7°C
Plant Family
Asteraceae
Growing Season
Cool Season
Plant Lifecycle
Annual
How to Start It
★ Recommended for beginners
Romaine likes cool weather and handles light frost, so sow it 2 to 4 weeks before your last spring frost, and again in late summer for fall. Sow the seeds thinly 0.5 cm deep and only just cover them, since lettuce seed needs a little light to sprout. They come up in 7 to 10 days: thin them (pull the extras) so each plant has 20 cm of room.
Romaine grows an upright, crisp heart, so it needs a little more room and time than loose-leaf lettuce, about 70 days. Hot weather makes it bolt (rush to flower and turn bitter), so sowing in the cool of spring and fall gives the best heads. Little Gem is a small, quick romaine that fits tight spaces and pots.
When To Start
First chance to plant
30 Days Before Last Frost
Last chance to plant
30 Days Before First Frost
When should you plant Romaine?
Your planting dates depend on your local climate. Sign up and add your location to unlock personalized dates.
Your Romaine Planting Window
Start planting
May 15, 2026
Last chance
Sep 10, 2026
Your Romaine Calendar
Set your location to turn these into exact dates and reminders.
Sow romaine outdoors and thin it to 20 cm apart
2 weeks before your last frost· every year
Optional: start romaine indoors in small cells
5 weeks before your last frost· every year· optional
Cut romaine heads once the heart feels firm
55 days after your last frost· every year· optional
Did you water your romaine seedlings today? Keep the top of the soil damp until they are up and growing.
About 1 days after you plant it
Time to thin the romaine seedlings: snip the extras at soil level so each one has room to grow.
About 20 days after you plant it
Your romaine is coming along! Thin the plants so each one has room to grow into a full head.
About 33 days after you plant it
Your romaine is nearly ready! Water evenly in warm weather to keep the leaves crisp and sweet.
About 57 days after you plant it
Picking time may be here: check your romaine.
About 70 days after you plant it
The Journey Ahead
Romaine's Lifecycle
Seedling
Mature Plant
Seed Production
Step 2
Planting & Sprouting
Expect sprouts in 7–10 days
Growing Tips
- 1Give romaine full sun in spring and fall, and some afternoon shade in hot weather.
- 2Mix compost into the soil before sowing, since lettuce grows fast and needs rich, crumbly soil.
- 3Water lightly and often so the soil never dries out, because dry soil makes the leaves bitter and pushes the plant to bolt.
- 4Feed with compost tea or worm castings every 2 to 3 weeks to build a dense heart.
- 5Sow a short row every 2 to 3 weeks instead of one big batch, so you always have heads coming on.
- 6Pick slugs off by hand in the evening, and spray aphids off with water.
Seedling Phase
Step 3
Growth & Maturity
~70
Days to Maturity
30 cm
Mature Height
20 cm
Mature Width
Pests to Watch For
Diseases to Watch For
Mature Plant
Step 4
Harvesting
Harvest Window
45 days
When to Pick
Cut heads when firm and upright
How to Harvest
- 1Romaine is ready when the head stands tall and the heart feels firm when you squeeze it gently, about 60 to 70 days after sowing.
- 2Cut the whole head with a sharp knife just above the soil.
- 3If you leave a short stump, it often grows a second, smaller crop of leaves.
- 4For a longer harvest, you can instead pick a few outer leaves at a time and let the heart keep growing.
- 5Harvest in the cool of the morning, when the leaves are crispest.
- 6Store heads unwashed in a bag in the fridge for up to a week.
Step 5
Saving Seeds
How to Save Seeds
Lettuce flowers pollinate themselves, so the seeds grow true as long as the variety is not a hybrid (hybrid F1 seeds will not), and keeping different varieties about 3 m apart is plenty. Let your best plant bolt, and do not save from the first plant to bolt, so you do not breed lettuce that bolts early. The small yellow flowers turn into fluffy white heads 2 to 3 weeks later, and they ripen a few at a time, so shake the heads into a paper bag every few days. Rub the seeds gently to remove the fluff, dry them a few more days, and store them labelled in a cool, dark, dry spot, where they keep about 3 years.
Seed Production
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