Sweet pea · Manhattan, New York, United States
When to sow sweet peas in Manhattan
Main outdoor window
4-25 Mar
The window this page is built around.
Timed from last spring frost
15 April
In Manhattan, on your chosen risk.
Ready to pick
2-22 Jun
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 Manhattan
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
4-25 Feb
Ten weeks before your last frost, under cover or on a windowsill.
Sow for overwintering
12 Jun - 3 Jul
Counting back 124 days from your first frost so the crop matures in time.
Sow direct
4-25 Mar
Six weeks before your last frost.
Plant out
18 Mar - 8 Apr
Four weeks before your last frost.
In flower
2-22 Jun
Sweet peas through the year
Against the frost risk in Manhattan
Why these dates
Sow in autumn and overwinter in a cold frame in zone 6 and warmer, or start ten weeks before last frost. Pinch at four true leaves.
Young plants take -8C and benefit from the cold. This is a flower where autumn sowing genuinely doubles the season.
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. Sweet peas are timed from 10 weeks before that frost for an indoor start, with planting out 4 weeks before it, and this page simply resolves those offsets against the frost date computed for Manhattan.
The median frost-free season here is 203 days, against 90 to 110 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Growing sweet peas in Manhattan
When should I plant sweet peas in Manhattan?
Aim for 4-25 Mar in an average year. If you would rather not gamble on the weather, wait until 13 Mar - 3 Apr - by then frost has finished in nine years out of ten.
When will sweet peas be ready to harvest in Manhattan?
Expect to start picking around 2-22 Jun, based on 90 to 110 days to maturity from the planting date calculated for this location.
How much frost will sweet peas tolerate?
Young plants take -8C and benefit from the cold. This is a flower where autumn sowing genuinely doubles the season.