Garden PlannerEvidence-aware. Garden with confidence.
Entire healthy mature lettuce plant in a real garden bed, showing growth habit and scale.Primary identification image. 15–30 cm tall, 20–30 cm wide at maturity.

Lettuce

Lactuca sativa L.

Also called: Leaf lettuce, Romaine, Butterhead, Crisphead

Family
Asteraceae
Season
Cool-season annual
Best grown in
Portland, Oregon

A cool-season leaf crop for spring and autumn, sown little and often; summer crops need afternoon shade and steady water.

Add to plan View companions Calendar

Life cycle & growth stages

  1. 1. SeedSurface-sow; needs light and cool soil.
  2. 2. SeedlingEmerges in 2–10 days.
  3. 3. TransplantSet out at 3–4 true leaves.
  4. 4. Mid-growthRosette expands; keep moist.
  5. 5. Harvest readyPick outer leaves or cut whole head.
  6. 6. HarvestCut above the crown for regrowth.
  7. 7. BoltingStem elongates in heat; leaves turn bitter.

Growth stages are ordered chronologically; timing varies with cultivar, temperature, light and care.

Planting calendar for Portland, Oregon

Start indoors 4–6 weeks before last frost; transplant 2 weeks before to 2 weeks after last frost; direct sow 4 weeks before to 4 weeks after last frost; 30–60 days to maturity from sowing. Windows are derived from the region's average frost dates (last Apr 5, first Nov 5) and are estimates until you confirm your own dates in the calendar.

LettuceLactuca sativa
PlantStart indoorsDirect sowAutumn sowTransplantTendHarvest
LettuceFeb 22–Mar 8 (estimate)Mar 8–May 3 (estimate); May 3–Sep 22 (estimate)Aug 27–Sep 24 (estimate)Mar 22–Apr 19 (estimate)—Apr 7–Dec 12 (estimate)
  • Start seeds indoors: Feb 22 – Mar 8
  • Direct sow: Mar 8 – May 3
  • Transplant outdoors: Mar 22 – Apr 19
  • Harvest: Apr 7 – Dec 12
  • Succession sow: May 3 – Sep 22
  • Autumn sowing: Aug 27 – Sep 24

Spacing & support

In-row 20–30 cm; rows 30–45 cm. Planner footprint: 1 cell of 30 cm, 2 plants per cell.

Side-profile diagram of mature lettuce: canopy 15–30 cm tall, 20–30 cm wide, shallow root zone, support and harvest-access envelope.

Soil & water

Soil
Moist, fertile loam
pH
6–7
Fertility
moderate
Water
Frequent light watering; never let the shallow roots dry out.
Frost
half hardy; tolerates frost

Support & training

No support structure needed.

Lettuce mid-season before harvest, showing branching, vining, rosette or upright habit and space occupied.

Harvest signs

  • Leaf types: outer leaves 10 cm long
  • Heads: firm when pressed lightly
  • Harvest in the morning before heat
Lettuce at harvest readiness, showing the visual cues: leaf types: outer leaves 10 cm long; heads: firm when pressed lightly.

Common problems

Pests: slugs and snails, aphids, cutworms

Diseases: downy mildew, bottom rot, tipburn (physiological)

Appearance alone is not a diagnosis; confirm with a regional extension guide.

Side-by-side: healthy lettuce leaf or fruit and an example of downy mildew.

Container growing

  • Minimum 5 L (15 cm deep)
  • Use quality potting mix and water more frequently
Mature lettuce in a correctly sized container (5 L or more) with drainage visible.

Companion overview

8 reviewed relationship records (evidence: medium).

Supported or conditional

Carrot, Corn, Peas, Sweet alyssum, Tomato

Avoid or separate

None with evidence

3 popular pairings reviewed with no verified relationship.

Full companion profile

Crop rotation

Avoid planting lettuce or other daisy family crops in the same spot for 1 year. Rotation is about previous seasons, not about live neighbours.

Year 1Year 2Year 3AsteraceaeOther familyOther familyback after 1+ years

Shared risks in Asteraceae: lettuce downy mildew, aphids, slugs on lettuce.

Crop rotation hub

Sources, reviewer & update

Sources

Reviewer: Garden Planner editorial team (pending independent horticultural review)

Last reviewed: August 15, 2026 · version 1

Found an error or have feedback? Let us know.

Growing lettuce

Lettuce germinates best at 10–20 °C and goes dormant above about 27 °C, so the reliable windows are early spring and late summer into autumn. Sow every two weeks in small quantities; a single large sowing bolts together.

Lettuce seed beside a ruler or coin for scale.
Lettuce seedling at cotyledon and first-true-leaf stage, in soil, distinguishable from common weeds.
Lettuce mid-season before harvest, showing branching, vining, rosette or upright habit and space occupied.

Leaf and cut-and-come-again types can be harvested from four weeks; heading types need 55–70 days and more space. Lettuce roots are shallow, so it suffers first in drought and benefits from mulch or the light shade of taller crops in summer — a spatial fit, not a companion claim.

Two or more mature lettuce plants with a tape measure showing in-row spacing (20–30 cm).
Lettuce flower detail or bolting stage.
Immature leaves of lettuce developing on the plant.

Slugs and aphids are the main pests; downy mildew and bottom rot appear in crowded, wet beds. Light frost is tolerated; hard frost is not.

Edible parts and safety

Edible: leaves.

Hands or tool harvesting lettuce correctly (cut, pull, twist or pick) without damaging the plant.

Pests and diseases

Common pests: slugs and snails, aphids, cutworms. Common diseases: downy mildew, bottom rot, tipburn (physiological). These vary by region; a photograph is an example, not a diagnosis. See the pest and disease guides and your local extension service.

slugs and snails on lettuce, with a wider damage-context view.

Timeline

Season timeline for lettuce: sowing, transplanting, flowering, harvest and bed occupancy aligned to frost dates.Text alternative: Start seeds indoors Feb 22–Mar 8; Direct sow Mar 8–May 3; Transplant outdoors Mar 22–Apr 19; Harvest Apr 7–Dec 12; Succession sow May 3–Sep 22; Autumn sowing Aug 27–Sep 24.

Related plants

See also: Asteraceae family page · crop rotation · regional calendar · guides

Our Methodology & Sources

We synthesize peer-reviewed research, university extension publications, and trusted horticulture resources. Our evidence levels help you understand how strong the science is behind the guidance.

Evidence tiers

Supported evidenceConsistent results from multiple robust studies
Traditional claimHistorical use reported, limited scientific support
Context dependentMixed or variable results across conditions
No verified relationshipNo reliable evidence identified

Primary source types

  • Peer-reviewed journal articles
  • University extension publications
  • Government & research institute reports
  • Systematic reviews & meta-analyses

Last updated

August 24, 2026

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