Lettuce
Lactuca sativa
A fast, cool-season annual for spring and fall — sow it shallow, keep it watered, and harvest before summer heat turns it bitter and sends it to seed.
At a glance
- Sun
- Full sun / Partial shade
- Water
- Moderate
- Soil pH
- 6–6.8
- Days to maturity
- 55–75
- from sowing; crisphead ~55+, butterhead ~70, leaf ~75 (Clemson)
- Spacing
- 6–12 in
- leaf 6–10 in; heading types 12 in; baby-leaf as close as 5 in; rows 12–36 in
- Germination soil
- 60–80°F
Mature size: Size varies widely by type, from low rosettes of loose leaves to dense heads — leaf, butterhead, romaine, and crisphead all grow differently.
Hardiness
Grown as a cool-season annual in every US zone. It tolerates light frost but bolts and turns bitter once days climb past about 75°F, so it is a spring-and-fall crop almost everywhere.
Sun
Full sun in spring and fall; in warm weather a little afternoon shade delays bolting. Minimum daily hours are not specified by the extension sources.
Water
About 1 inch of water per week, more in hot, dry spells — shallow roots dry out fast.
Planting calendar
Timed to your own frost dates — look up yours by ZIP on the home page.
- Start indoors 4–6 weeks before your last spring frost. UMN suggests ~4 weeks; Utah State allows 5–6 weeks before transplanting.
- Transplant — Set transplants out around your last frost date — lettuce tolerates light frost. Harden seedlings off first.
- Direct sow — Sow ¼–½ inch deep as soon as the soil can be worked, about 2–3 weeks before the last frost. For a fall crop, sow roughly three months before your first fall frost.
Lettuce is a cool-season crop that grows best when nights are around 50°F and days stay below about 68°F. It germinates and grows fast, which makes it one of the most rewarding things to sow early — and one of the first to fail when summer arrives.
Beat the heat, or it bolts
Once temperatures climb past roughly 75°F, lettuce bolts — it sends up a flower stalk and the leaves turn bitter. That single fact shapes the whole growing strategy: plant early in spring, plant again for fall, and skip the hottest stretch of summer. In warm regions, light afternoon shade and slow-bolt or heat-resistant varieties buy you extra time.
Sow shallow, sow often
Lettuce seed is tiny and needs light and cool soil to germinate, so sow it only ¼–½ inch deep. Rather than planting it all at once, succession-sow a short row every couple of weeks through spring and again in late summer for fall. That spreads the harvest out instead of giving you more heads than you can eat in one week.
Harvest
Leaf types are perfect for cut-and-come-again harvesting: snip the outer leaves and the plant keeps producing from the center. Heading types are cut whole once the head firms up. Either way, harvest in the cool of the morning and pick before the plant bolts.
Common pests
- Aphids
- Cabbage looper
- Corn earworm
- Leafhoppers
- Slugs
- Cutworms
Common diseases
- Gray mold (Botrytis)
- Bottom rot (Rhizoctonia)
- Sclerotinia drop
- Aster yellows