When to plant onion in Columbus
Onion is cold-hardy, so every date keys off Columbus's frost dates of Apr 16.
Step 1 · Sow
Start seeds indoors
Feb 5 – Feb 26
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 17 – May 8
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 16 – Aug 5
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Columbus's 188-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
APR 16
OCT 25
Common questions
When will onion be ready to harvest in Columbus?
Expect to harvest from around mid July (Jul 16–Aug 5) in Columbus, based on its local frost dates. Confidence 80%.
When should I start onion seeds indoors in Columbus?
Start seeds indoors around early February (Feb 5–Feb 26) in Columbus, based on its local frost dates. Confidence 85%.
When can I transplant onion outdoors in Columbus?
Transplant outdoors around mid April (Apr 17–May 8) in Columbus, based on its local frost dates. Confidence 86%.
How long is the growing season in Columbus?
Columbus has roughly 188 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 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.