When to plant onion in Adelaide
Onion is cold-hardy, so every date keys off Adelaide's frost dates of Aug 15.
Step 1 · Sow
Start seeds indoors
Jun 6 – Jun 27
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jul 25 – Aug 15
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Oct 23 – Nov 12
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Adelaide's 304-day season leaves this much room.
Onion on Adelaide'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
AUG 15
JUN 15
Common questions
When will onion be ready to harvest in Adelaide?
Expect to harvest from around late October (Oct 23–Nov 12) in Adelaide, based on its local frost dates. Confidence 72%.
When should I start onion seeds indoors in Adelaide?
Start seeds indoors around early June (Jun 6–Jun 27) in Adelaide, based on its local frost dates. Confidence 76%.
When can I transplant onion outdoors in Adelaide?
Transplant outdoors around late July (Jul 25–Aug 15) in Adelaide, based on its local frost dates. Confidence 80%.
How long is the growing season in Adelaide?
Adelaide has roughly 304 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 Adelaide's frost dates.
Confidence 80/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.