In zone 4, plant lettuce outside from April 18 to April 25, three to four weeks before your last spring frost. Sow again in late summer for a fall crop: the last sowing date is about July 31.
Lettuce dates for your ZIP code
Planting times based on university extension guidance (UNH, Cornell, Purdue, Minnesota, Nebraska and UMass Extension). Frost dates from NOAA 1991–2020 U.S. Climate Normals, nearest weather station. Zones derived from the 2023 USDA Plant Hardiness Zone Map data (PRISM Climate Group, Oregon State University). This is not the official USDA Plant Hardiness Zone Map.
Lettuce timing in zone 4
| Task | When |
|---|---|
| Start indoors (optional) | March 14 – March 21 |
| Plant outside | April 18 – April 25 |
| First harvest | June 7 – June 24 |
| Sow for fall by | July 31 |
| Sow again | Every couple of weeks in spring for a steady supply |
| Protect from hard freezes | With a row cover, early and late in the season |
Most of zone 4 sees its last spring frost between May 11 and May 23 (typical May 16) and its first fall frost between September 21 and September 29 (typical September 25). Lettuce handles light frost, so early planting is fine, but cover it if a hard freeze is forecast. The tool above uses the weather station closest to your ZIP code.
Why lettuce is planted before the last frost
Lettuce is a cool-season, semi-hardy crop. It tolerates light frost and grows best in mild weather, so it goes into the garden weeks before the last spring frost. Heat and long summer days make it bolt: the plant sends up a flower stalk and the leaves turn bitter. That is why lettuce is grown in spring and again in fall.
Best lettuce varieties for zone 4
Zone 4 summers are cool enough that lettuce often grows well into early summer. All four main types work:
- Leaf lettuce is the fastest and easiest, ready to pick when 5–6 inches tall. Try Grand Rapids, Black Seeded Simpson, Salad Bowl or Red Sails.
- Butterhead forms soft, loose heads. Try Buttercrunch.
- Romaine forms tall, upright heads. Try Parris Island Cos or Winter Density.
- Crisphead (iceberg) needs a long, cool season, which zone 4 can provide. Try Great Lakes or Ithaca.
How to plant lettuce
- Sow seeds ¼ inch deep directly in the garden, or start transplants indoors four to five weeks ahead.
- Thin leaf lettuce to 4–8 inches apart when seedlings are 1–2 inches tall. You can eat the thinnings.
- Space heading types wider: butterhead and romaine 6–10 inches apart, crisphead 12–15 inches.
- Water lightly and often to keep growth fast and tender.
- Sow small batches every couple of weeks for a steady harvest.
Zone 4 lettuce tips
- Start early. Sow leaf and butterhead lettuce as soon as the soil can be worked in spring.
- Sow in small batches. A short row every couple of weeks gives you salad all season instead of one glut.
- Water lightly and often for fast, tender growth, preferably in the morning so the leaves dry during the day.
- Watch for a summer slowdown. Long days and warm spells make lettuce bolt and turn bitter. Pick heads before that happens.
Harvesting lettuce
Pick leaf lettuce when plants are 5–6 inches tall, starting with the outer leaves, or cut whole plants an inch above the soil: they often regrow for a second cut in two to three weeks. Harvest butterhead when the leaves cup inward, romaine when it forms a head 6–8 inches tall, and crisphead when the head feels firm. Store lettuce dry and unwashed in a bag in the refrigerator.
Lettuce planting dates in nearby zones
See dates for every zone on the lettuce planting guide, or build a full schedule with the planting calendar.
Frequently asked questions
Is it too late to plant lettuce in zone 4 in May?
Not for leaf lettuce, which matures quickly. Heading types need a longer cool spell, so if you sow in May, choose leaf lettuce or wait and sow for fall.
Can lettuce survive frost in zone 4?
Light frost, yes. Lettuce is semi-hardy, but a hard freeze damages it, so cover plants with a row cover when one is forecast.
Can I plant lettuce before the last frost?
Yes. Lettuce tolerates light frost and grows best in cool weather, so it is planted three to four weeks before your last spring frost.
How often should I sow lettuce?
Sow a short row every couple of weeks. That gives you a steady supply instead of more lettuce than you can eat at once.
Why is my lettuce bitter?
Heat and long days make lettuce bolt and turn bitter. Harvest before hot weather, and choose slow-bolting varieties for late spring.
Sources. Planting dates use the median frost dates of each USDA zone, calculated from NOAA climate data for every ZIP code in the zone.