When to plant onion in Columbus
Onion is cold-hardy, so every date keys off Columbus's frost dates of Mar 6.
Step 1 · Sow
Start seeds indoors
Dec 26 – Jan 16
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Feb 13 – Mar 6
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 14 – Jun 3
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Columbus's 262-day season leaves this much room.
Onion on Columbus'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 6
NOV 22
Common questions
When will onion be ready to harvest in Columbus?
Expect to harvest from around mid May (May 14–Jun 3) in Columbus, based on its local frost dates. Confidence 79%.
When should I start onion seeds indoors in Columbus?
Start seeds indoors around late December (Dec 26–Jan 16) in Columbus, based on its local frost dates. Confidence 84%.
When can I transplant onion outdoors in Columbus?
Transplant outdoors around mid February (Feb 13–Mar 6) in Columbus, based on its local frost dates. Confidence 88%.
How long is the growing season in Columbus?
Columbus has roughly 262 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 Columbus's frost dates.
Confidence 88/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.