Cosmos · New York City, New York, United States
When to sow cosmos in New York City
Main outdoor window
5-19 Apr
The window this page is built around.
Timed from last spring frost
29 March
In New York City, on your chosen risk.
Ready to pick
14 Jun - 4 Jul
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 New York City
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
1-15 Mar
Four weeks before your last frost, under cover or on a windowsill.
Sow direct
5-19 Apr
One week after your last frost.
Plant out
5-19 Apr
One week after your last frost.
In flower
14 Jun - 4 Jul
Cosmos through the year
Against the frost risk in New York City
Why these dates
Sow direct around the last frost date. Pinch young plants once to produce a bushier, more productive plant.
Frost-tender at both ends, but flowers freely until the first autumn frost stops it outright.
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. Cosmos are timed from 4 weeks before that frost for an indoor start, with planting out 1 weeks after it, and this page simply resolves those offsets against the frost date computed for New York City.
The median frost-free season here is 249 days, against 70 to 90 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in New York City
Other flowers to time
Growing cosmos in New York City
When should I plant cosmos in New York City?
Aim for 5-19 Apr in an average year. If you would rather not gamble on the weather, wait until 15-29 Apr - by then frost has finished in nine years out of ten.
When will cosmos be ready to harvest in New York City?
Expect to start picking around 14 Jun - 4 Jul, based on 70 to 90 days to maturity from the planting date calculated for this location.
How much frost will cosmos tolerate?
Frost-tender at both ends, but flowers freely until the first autumn frost stops it outright.