When to plant onion in Wellington
Onion is cold-hardy, so every date keys off Wellington's frost dates of Sep 19.
Step 1 · Sow
Start seeds indoors
Jul 11 – Aug 1
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Aug 29 – Sep 19
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Nov 27 – Dec 17
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Wellington's 256-day season leaves this much room.
Onion on Wellington'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
SEP 19
JUN 2
Common questions
When will onion be ready to harvest in Wellington?
Expect to harvest from around late November (Nov 27–Dec 17) in Wellington, based on its local frost dates. Confidence 45%.
When should I start onion seeds indoors in Wellington?
Start seeds indoors around mid July (Jul 11–Aug 1) in Wellington, based on its local frost dates. Confidence 48%.
When can I transplant onion outdoors in Wellington?
Transplant outdoors around late August (Aug 29–Sep 19) in Wellington, based on its local frost dates. Confidence 50%.
How long is the growing season in Wellington?
Wellington has roughly 256 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 Wellington's frost dates.
Confidence 50/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.