Lettuce

Lactuca sativa

Asteraceae · annual · introduced

Last updated May 23, 2026

Quick Facts

Height

6-12 in (vegetative); 2-4 ft (bolting)

Spread

6-12 in

Growth Rate

Fast

Light

Full Sun

Soil

Well Drained

Water

Moderate

Hardiness

Zones 2–11 (grown as annual)

Bloom Time

Bolts in response to heat and long days; typically July-August if spring-planted

Fall Color

N/a (annual; harvested before senescence)

Origin

Mediterranean region, Near East

Damping-offHigh

Spring Sowing - Preemergence Damping-off Risk

Downy MildewHigh

Spring New Growth - Early Infection Window

Powdery MildewModerate

Spring Emergence / Primary Infection

Diseases: Regionally Documented (7)

Multiple obligate oomycetes (Peronosporaceae); species ar... Downy Mildew Drop (Sclerotinia Rot) Gray Mold Multiple obligate biotrophic fungi (Erysiphales: Erysipha... Powdery Mildew Bottom Rot Several soilborne Damping-off Tipburn

Pests: Regionally Documented (3)

Slugs and Snails Aphids Noctuidae Cutworms and Armyworms

Phenological Calendar

View full calendar (7 stages)

Stage	Typical Window	What to Look For
Spring direct sow BBCH 00	Mar 1-Apr 15	Soil workable, temps above 40°F
Emergence BBCH 09	Mar 10-Apr 25	Cotyledons emerged above soil
Rosette formation BBCH 19	Apr 1-May 15	Full rosette of true leaves; baby leaf harvest possible
Head formation BBCH 45	Apr 15-Jun 1	Inner leaves cupping inward; head firming
Harvest maturity BBCH 49	May 1-Jun 30 (spring); Sep 1-Nov 15 (fall)	Full-size head or leaves at target size
Bolting BBCH 51	Jul 1-Aug 15	Central stem elongating rapidly; leaves becoming bitter
Fall sowing BBCH 00	Aug 1-Sep 15	Direct sow or transplant for fall harvest

Cultivars (3)

'Black Seeded Simpson'

Loose-leaf. Light green, crinkled leaves. Very fast to harvest. Heat-tolerant for a lettuce.

Reliable spring and fall crop in Puget Sound

'Buttercrunch'

Butterhead type. Dark green, thick leaves, loose head. Good heat tolerance.

AAS winner; reliable in PNW

'Winter Density'

Semi-cos (romaine/butterhead cross). Dark green, compact, cold-hardy. Excellent for fall/winter harvest under row cover.

Top choice for fall/winter lettuce in Western Washington

Data Maturity

Baseline Extension data. Expert review underway.