Thinning lettuce seedlings

Lettuce needs room to reach full size. The right spacing depends on the type and how big you plan to let it grow.

When we suggest this

• Your noteIt is 14–28 days after the planting date you gave from seed.

What would stop us suggesting it

• If it's still open after its window, it shows as overdue for up to 2 weeks, then closes.
• When you mark it Done or Doesn't apply. "Doesn't fit my setup" stops it for that plant this season.

What to do

1. Thin once most seedlings are 1–2 inches tall or have 3–4 true leaves.
2. Pull extras gently, or snip them at soil level, so the plants you keep stand apart.
3. Leave about 4 inches between leaf lettuce, 6–8 inches for romaine and butterhead, and 10–12 inches for full-size heads.
4. Eat the thinnings as baby greens.

What we can't know

• How thickly you sowed and how many seedlings came up.
• Which type you're growing. Spacing depends on it.

The 14–28 day window is our estimate. Lettuce usually comes up 4–10 days after sowing, and sources say to thin at 1–2 inches tall (Clemson) or at 3–4 true leaves (Utah State); cold soil makes this later. Spacing varies by type and harvest size, from about 4 inches for leaf lettuce picked young to 10–12 inches (Utah State: 8–12) for full-size plants.

Where this advice applies

All US regions.

Any US garden where lettuce is sown directly outdoors.

Cold soil slows sprouting and early growth, so seedlings may still be tiny at two weeks.

Exceptions

• Lettuce you set out as transplants.
• Lettuce you sowed thickly on purpose to cut young as baby greens.
• Plants you've marked finished.

Related guide sections

• Growing lettuce: through the season

Reviewed

Sources checked Sept 2026 · awaiting expert review

Gardenplanner research (AI-assisted), pending extension-qualified review

Rule id and version: lettuce.thin@1