When to plant onion in Christchurch
Onion is cold-hardy, so every date keys off Christchurch's frost dates of Oct 10.
Step 1 · Sow
Start seeds indoors
Aug 1 – Aug 22
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Sep 19 – Oct 10
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Dec 18 – Jan 7
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Christchurch's 192-day season leaves this much room.
Onion on Christchurch'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
OCT 10
APR 20
Common questions
When will onion be ready to harvest in Christchurch?
Expect to harvest from around mid December (Dec 18–Jan 7) in Christchurch, based on its local frost dates. Confidence 72%.
When should I start onion seeds indoors in Christchurch?
Start seeds indoors around early August (Aug 1–Aug 22) in Christchurch, based on its local frost dates. Confidence 76%.
When can I transplant onion outdoors in Christchurch?
Transplant outdoors around mid September (Sep 19–Oct 10) in Christchurch, based on its local frost dates. Confidence 80%.
How long is the growing season in Christchurch?
Christchurch has roughly 192 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 Christchurch's frost dates.
Confidence 80/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.