Harvest · Signals, not a promise
When to harvest lettuce
When to harvest lettuce here is cited harvest signals. Leaf, bibb, romaine, and head stay type-separated. Bolting is another page. Those cues are not how long yours keeps.
Growing guidance is general information. Timing, spacing, and care depend on cultivar, weather, soil, and local conditions. Check the sources and adjust the plan for your garden.
Illustrative photograph — harvest signals stay on the cited sheets.
Growing lives on how to grow lettuce. Timing lives on when to plant lettuce. Seed-stalk notes live on lettuce bolting.
What the sources say — at a glance
One source per card. Facts are not averaged.
Clemson HGIC 1318 (South Carolina)
Leaf at 5–6 in. Bibb: leaves cup inward, loose head. Romaine: elongate/overlap, 6–8 in tall. Head: leaves overlap. Type-separated cues.
Details and limits (5)
Leaf
Clemson HGIC 1318 (South Carolina): leaf lettuce can be used as soon as plants are 5 to 6 inches tall. Cue on their sheet — not a keeping promise.
Bibb
Clemson HGIC 1318 (South Carolina): bibb lettuce is mature when leaves begin to cup inward to form a loose head.
Romaine
Clemson HGIC 1318 (South Carolina): cos or romaine is ready to use when the leaves have elongated and overlap to form a partially tight head about 6 to 8 inches tall.
Head
Clemson HGIC 1318 (South Carolina): head lettuce is mature when leaves overlap to form a head similar to those available in the stores.
Limit
South Carolina lettuce sheet. Type cues stay separate. Not a fridge page and not a bolting page.
Maryland Extension (Maryland)
Leaf 5–6 in; outer leaves first; thin by harvesting every other large plant. Bibb cup inward. Romaine ~4 in wide × 6–8 in tall. Crisphead compact and firm.
Details and limits (5)
Leaf
Maryland Extension (Maryland): leaf lettuce can be used as soon as plants are 5 to 6 inches tall. Use the older, outer leaves first. You may harvest every other one of the largest plants to accomplish thinning. Cue on their sheet — not a keeping promise.
Bibb
Maryland Extension (Maryland): bibb is mature when the leaves begin to cup inward to form a loose head.
Romaine
Maryland Extension (Maryland): romaine or cos is ready when the leaves have elongated and overlapped to form a fairly tight head about 4 inches wide at the base and 6 to 8 inches tall.
Crisphead
Maryland Extension (Maryland): crisphead is mature when leaves overlap to form a compact and firm head.
Limit
Maryland lettuce garden page. Type cues stay separate. Not a fridge page and not a bolting page.
UMN Extension (Minnesota)
Single leaves at usable size; baby-stage leaves leaving small ones; or whole plant cut at soil. Two methods — not one protocol.
Details and limits (3)
Leaf
UMN Extension (Minnesota): harvest single leaves as soon as they reach a usable size. You may harvest individual leaves at the baby stage, leaving most of the small leaves on the plant. Cue on their sheet — not a keeping promise.
Whole plant
UMN Extension (Minnesota): you can also remove the whole plant by cutting it off at or just above the soil surface. Two methods on their sheet — not one BioArva protocol.
Limit
Minnesota lettuce sheet. Leaf vs whole-plant stay distinct. Not a bolting page.
Illinois Extension (Illinois)
Cut at the soil line. Their sheet also describes cutting every other plant. Illinois methods — not a national size rule.
Details and limits (2)
Leaf
Illinois Extension (Illinois): once leaf lettuce leaves are developed, the lettuce can be cut off at the soil line. Their sheet also describes cutting every other plant. Illinois methods — not a national size rule.
Limit
Illinois how-to-grow-lettuce post. Soil-line and every-other-plant as cited. Not a bolting page.
Sources differ
Make it yours
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How do you know when leaf lettuce is ready to pick?
Compare leaf cues on the cited sheets. Clemson HGIC 1318 (South Carolina): as soon as plants are 5 to 6 inches tall. Maryland: 5 to 6 inches tall; older, outer leaves first.
Is heading lettuce picked the same way as leaf lettuce?
No. Types stay separate. Clemson: bibb when leaves cup inward to a loose head; romaine when leaves elongate and overlap about 6 to 8 inches tall; head when leaves overlap. Maryland: crisphead when leaves overlap to a compact and firm head.
How we know — methodology. Ranges and assertions are cited per source, not blended.