When to plant onion in New York City
Onion is cold-hardy, so every date keys off New York City's frost dates of Mar 30.
Step 1 · Sow
Start seeds indoors
Jan 19 – Feb 9
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 13 – May 4
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 12 – Aug 1
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
New York City's 234-day season leaves this much room.
Onion on New York City's growing year
Frost-bounded season with crops mapped onto the 12-month axis.
Frost risk Growing Harvest
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
FROST
FROST
MAR 30
NOV 19
Common questions
When will onion be ready to harvest in New York City?
Expect to harvest from around mid July (Jul 12–Aug 1) in New York City, based on its local frost dates. Confidence 80%.
When should I start onion seeds indoors in New York City?
Start seeds indoors around mid January (Jan 19–Feb 9) in New York City, based on its local frost dates. Confidence 85%.
When can I transplant onion outdoors in New York City?
Transplant outdoors around mid April (Apr 13–May 4) in New York City, based on its local frost dates. Confidence 86%.
How long is the growing season in New York City?
New York City has roughly 234 frost-free days, which is enough time to grow onion to maturity outdoors.
The rule of thumb
Sow onion as soon as the soil is workable — it tolerates cool weather and light frost. Every date on this page is derived from that rule and New York City's frost dates.
Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.