Lettuce is a cool-season crop, and Pennsylvania gives you two excellent windows each year to grow it: a spring window starting in March and a fall window starting in late summer. The trick is hitting those windows accurately — plant too early and a hard frost kills seedlings; plant too late and heat bolts the crop before you get a real harvest.
This guide gives exact dates by Pennsylvania zone for both windows, a succession planting schedule to keep harvests continuous, and the soil temperature thresholds that determine whether your seeds will actually germinate.
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📅 Lettuce Planting Calendar — Pennsylvania (Zones 5a–7a)
Harvest Window
Fall Sowing
Dormant / Heat Gap
🥬 Lettuce Planting Quick Reference — Pennsylvania
Spring Planting Windows by Pennsylvania Zone
Lettuce tolerates light frost — established plants can handle temperatures down to about 28°F, and seedlings can survive brief dips to 26°F. This makes it one of the first crops you can get in the ground each spring. The key metric is soil temperature, not air temperature. Lettuce seed germinates in soil as cool as 40°F, though germination is slow at that temperature. At 50–65°F it’s much faster and more uniform.
For most of Pennsylvania, direct sowing can begin in mid-March (zone 6b–7a near Philadelphia) to early April (zones 5a–5b in northern and high-elevation areas). The goal is to get plants established and producing before sustained daytime temperatures exceed 75°F. In zone 7a, you have a long spring window — 8–10 weeks of productive growing from late March to early June. In zone 5a, the window compresses to 6–8 weeks from early April to late May.
Starting Indoors for Earlier Harvest: Starting lettuce indoors 4–6 weeks before your outdoor sowing date gives you transplants ready to go in the ground earlier, extending the harvest window. Sow into cell trays under grow lights, transplant outdoors as 3–4 week-old seedlings (when they have 2–3 true leaves). This is particularly worth doing in zones 5a–5b where the outdoor sowing window is short.
Fall Planting Windows — Often Better Than Spring
Pennsylvania fall lettuce is, in my experience, more reliable than spring lettuce. You’re working with shortening days and falling temperatures — conditions that favor leaf production over bolting. The main challenge is timing the sow date so plants reach harvestable size before hard frosts arrive.
The formula is simple: count back 8–10 weeks from your first expected fall frost. For most of central and western PA, that means a first frost around October 10–20, which means sowing from late July through mid-August. Zone 7a near Philadelphia has a later first frost (October 20 – November 1), pushing the sowing window into late July through late August. Zone 5a in northern PA has an earlier first frost (October 1–10), requiring sowing from late July through early August.
Fall-sown lettuce can be protected with row cover or cold frames to extend the harvest well into November, and sometimes through December in southern PA. A simple hoop tunnel with 1.5 oz row cover can provide 4–6°F of frost protection — enough to carry fall lettuce through several hard frosts that would otherwise end the season.
Free PA Planting Calendar
Zone-specific · 4 pages · Instant download
Get the exact dates for your Pennsylvania zone — when to start seeds indoors, direct sow, transplant, and harvest. Built around your local frost window, not a generic national average.
- Wall chart with all key dates
- Seed-start schedule (50+ crops)
- First & last frost reference
- Soil temp cheat sheet
Succession Planting: Continuous Harvest, No Gluts
The single biggest mistake with lettuce is planting it all at once. A 10-foot row of lettuce will head up simultaneously and give you far more than you can use in the 2–3 weeks it stays at peak quality — then it bolts and it’s over. Succession planting every 2 weeks spreads the harvest across the full season. The Old Farmer’s Almanac lettuce guide outlines the general succession approach well if you want a second reference.
During the spring window, sow a small amount every 14 days from your first direct sow date until temperatures are regularly reaching 70°F. That gives most PA gardeners 4–6 successions from March through May. In zone 7a you might get one or two more; in zone 5a, one or two fewer.
The same logic applies in fall. Start your fall sowing around August 1–7 (most of PA) and sow again every 2 weeks through late August. You’ll get 2–3 fall successions, with the earliest harvest in late September and the last — potentially under row cover — in October or November.
Mix Varieties Within Each Succession: Within each sowing, mix a fast loose-leaf (45 days) with a slower butterhead or romaine (65–75 days). This creates a natural spread of harvest timing even within a single batch — you’ll be pulling loose-leaf leaves while the heading types are still sizing up.
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Soil Temperature and Germination
Lettuce seed is temperature-sensitive in a way that surprises many gardeners. It germinates across a wide range — 40–75°F — but has a quirk: it becomes thermally dormant above about 75–80°F. This means sowing lettuce into warm soil in late August can actually fail to germinate, even though the fall timing is correct. The seed goes dormant instead of sprouting.
The solution for late-summer fall sowing is to pre-chill seeds before planting. Fold seeds in a damp paper towel, seal in a plastic bag, and refrigerate for 24–48 hours. This breaks thermal dormancy and dramatically improves germination rates in warm August soil. Penn State Extension recommends this technique specifically for fall lettuce started in late July and early August when PA soil temperatures are above 75°F.
You can also sow in the evening when temperatures are cooler, or shade the seeded area with a board or row cover for the first few days until germination begins. Once lettuce seeds have sprouted, they handle warmer temperatures well during the day.
Extending the Season: Cold Frames and Row Cover
With minimal protection, Pennsylvania lettuce growers can extend both ends of the season significantly. In spring, a simple row cover or cold frame allows you to start 2–4 weeks earlier than outdoor conditions would otherwise permit — mid-February in zone 7a, early March in zones 5b–6b. In fall, the same protection extends the harvest from October into November, and in southern PA zones, sometimes through early December.
Row cover (1.5 oz weight): Provides about 4–6°F of frost protection. Laid directly over plants or on low hoops, it’s the easiest and most versatile season extension tool. It also doubles as protection from aphids and other early-season pests.
Cold frames: Provide 8–12°F of frost protection depending on construction and weather. A simple wooden frame with an old window sash on top is enough to grow lettuce through most Pennsylvania winters in zones 6b–7a. Ventilate on warm days to prevent overheating — lettuce doesn’t want temperatures above 75°F even in a cold frame.
Zone-by-Zone Lettuce Planting Calendar
Click your region to highlight your row. Not sure which zone you’re in? See our Pennsylvania hardiness zones guide for a county-by-county breakdown.
| PA Region | Spring First Sow | Spring Last Sow | Fall First Sow | Fall Last Sow | First Fall Frost |
|---|---|---|---|---|---|
| Northern PA (Zone 5a–5b) |
Late March – early April | Mid May | Late July | Early August | Oct 1–10 |
| Western PA (Zone 6a) |
Mid March | Late May | Late July – Aug 1 | Mid August | Oct 10–20 |
| Central PA (Zone 5b–6b) |
Late March | Late May | Late July – Aug 1 | Mid August | Oct 5–15 |
| Eastern PA (Zone 6b–7a) |
Early–mid March | Early June | Late July – Aug 7 | Late August | Oct 20 – Nov 1 |
Season planning: Check our month-by-month Pennsylvania planting guide to keep your garden producing all year. Browse all Pennsylvania vegetable guides for companion planting ideas.
Frequently Asked Questions About Planting Lettuce in Pennsylvania
1. Can I plant lettuce in March in Pennsylvania?
Yes — for most of PA, mid-to-late March is appropriate for direct sowing as long as the soil is workable and at least 40°F. Zone 7a (Philadelphia and surroundings) can sow as early as early March. Zone 5a (northern PA, high elevations) should wait until late March or early April. Lettuce tolerates light frosts on established plants, but freshly sown seeds need soil above 40°F to germinate. A soil thermometer is the most reliable way to confirm timing.
2. My lettuce bolted before I got a good harvest — what went wrong?
Most commonly: the sowing date was slightly late, and a warm May pushed temperatures past the bolt threshold before plants reached full harvest size. The fix is sowing 1–2 weeks earlier and choosing a bolt-resistant variety (Buttercrunch, Jericho, Black Seeded Simpson, Oakleaf). Also check if you’re growing a heat-sensitive type like Boston butterhead or crisphead — these bolt faster than modern bolt-resistant varieties. Getting some afternoon shade over the plants in late May extends the window noticeably.
3. When should I plant lettuce for a fall harvest in PA?
Count back 8–10 weeks from your first expected fall frost. For most of central and western PA, that’s late July through early August (first frost around October 10–20). For zone 7a near Philadelphia, you can sow through late August. The critical issue with late summer sowing is soil temperature — if the soil is above 75–80°F, seeds may go dormant instead of germinating. Chill seeds for 24–48 hours in the refrigerator before sowing to break thermal dormancy.
4. How deep do I sow lettuce seeds in Pennsylvania?
Very shallow — 1/8 to 1/4 inch deep, or simply pressed into the surface and kept moist. Lettuce seeds need light to germinate. Burying them more than 1/4 inch significantly reduces germination rates. In dry conditions, covering with a thin layer of vermiculite (which retains moisture while staying loose) works better than soil for maintaining the moist surface conditions lettuce needs to sprout.
5. Should I start lettuce indoors or direct sow in Pennsylvania?
Both work well. Direct sowing is simpler — lettuce doesn’t have a strong preference either way and transplants easily without much shock. Starting indoors is worth doing for the very first spring sowing (early March) when outdoor conditions are marginal, and for getting a 2–3 week head start in zones 5a–5b where the outdoor window is short. For succession plantings after mid-April, direct sowing is faster and easier. Fall succession sowings are almost always direct sow.
6. Can I grow lettuce year-round in Pennsylvania?
With protection, yes — though it requires more effort in the coldest months. In zones 6b–7a, a well-built cold frame or low tunnel can sustain lettuce through most winters with minimal care — growth slows dramatically in January and February but plants survive and resume in March. In zones 5a–5b, you’ll need a more substantial structure (a heated greenhouse or insulated cold frame) to maintain lettuce through the coldest stretch of winter. Without protection, lettuce production in PA typically runs March through early July and late July through November.
Continue Reading: Lettuce in Pennsylvania
- Best Lettuce Varieties for Pennsylvania — bolt-resistant loose-leaf, butterhead, and romaine picks for PA
- How to Grow Lettuce in Pennsylvania — soil prep, spacing, watering, and preventing bolt
- Growing Lettuce in Raised Beds in Pennsylvania — why raised beds extend the PA lettuce season
