When to plant onion in Oklahoma City
Onion is cold-hardy, so every date keys off Oklahoma City's frost dates of Apr 3.
Step 1 · Sow
Start seeds indoors
Jan 23 – Feb 13
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Mar 16 – Apr 6
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 14 – Jul 4
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Oklahoma City's 223-day season leaves this much room.
Onion on Oklahoma 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
APR 3
NOV 5
Common questions
When will onion be ready to harvest in Oklahoma City?
Expect to harvest from around mid June (Jun 14–Jul 4) in Oklahoma City, based on its local frost dates. Confidence 79%.
When should I start onion seeds indoors in Oklahoma City?
Start seeds indoors around late January (Jan 23–Feb 13) in Oklahoma City, based on its local frost dates. Confidence 84%.
When can I transplant onion outdoors in Oklahoma City?
Transplant outdoors around mid March (Mar 16–Apr 6) in Oklahoma City, based on its local frost dates. Confidence 85%.
How long is the growing season in Oklahoma City?
Oklahoma City has roughly 223 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 Oklahoma City's frost dates.
Confidence 88/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.