When to plant onion in Tulsa
Onion is cold-hardy, so every date keys off Tulsa's frost dates of Mar 31.
Step 1 · Sow
Start seeds indoors
Jan 20 – Feb 10
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
Tulsa's 214-day season leaves this much room.
Onion on Tulsa'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 31
NOV 3
Common questions
When will onion be ready to harvest in Tulsa?
Expect to harvest from around mid June (Jun 14–Jul 4) in Tulsa, based on its local frost dates. Confidence 79%.
When should I start onion seeds indoors in Tulsa?
Start seeds indoors around mid January (Jan 20–Feb 10) in Tulsa, based on its local frost dates. Confidence 84%.
When can I transplant onion outdoors in Tulsa?
Transplant outdoors around mid March (Mar 16–Apr 6) in Tulsa, based on its local frost dates. Confidence 85%.
How long is the growing season in Tulsa?
Tulsa has roughly 214 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 Tulsa's frost dates.
Confidence 88/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.