Lettuce · Philadelphia, Pennsylvania, United States
When to plant lettuce in Philadelphia
Main outdoor window
24 Mar - 7 Apr
The window this page is built around.
Timed from last spring frost
14 April
In Philadelphia, on your chosen risk.
Ready to pick
8-23 May
If you plant at the start of the window.
The average last frost. Half of all years are later than this.
Step by step in Philadelphia
Each window is a range, not a single day. Earlier in the range buys you a longer season; later in it buys you a safer one.
Start indoors
3-17 Mar
Six weeks before your last frost, under cover or on a windowsill.
Sow for autumn
30 Jul - 20 Aug
Counting back 74 days from your first frost so the crop matures in time.
Sow direct
24 Mar - 7 Apr
Three weeks before your last frost.
Plant out
31 Mar - 14 Apr
Two weeks before your last frost.
Harvest
8-23 May
Lettuce through the year
Against the frost risk in Philadelphia
Why these dates
Sow every ten days from six weeks before last frost. Pause through midsummer, then resume for an autumn crop - late sowings are often the best of the year.
Tolerates -3C and a light frost actually sweetens the leaf. Seed germinates poorly above 25C, which is the more common problem.
Seed packets and extension guides express timing as weeks either side of the last spring frost, because that is the only reference point that travels. Lettuce are timed from 6 weeks before that frost for an indoor start, with planting out 2 weeks before it, and this page simply resolves those offsets against the frost date computed for Philadelphia.
The median frost-free season here is 202 days, against 45 to 60 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Philadelphia
Other vegetables to time
Growing lettuce in Philadelphia
When should I plant lettuce in Philadelphia?
Aim for 24 Mar - 7 Apr in an average year. If you would rather not gamble on the weather, wait until 2-16 Apr - by then frost has finished in nine years out of ten.
When will lettuce be ready to harvest in Philadelphia?
Expect to start picking around 8-23 May, based on 45 to 60 days to maturity from the planting date calculated for this location.
How much frost will lettuce tolerate?
Tolerates -3C and a light frost actually sweetens the leaf. Seed germinates poorly above 25C, which is the more common problem.