When to plant onion in Marseille
Onion is cold-hardy, so every date keys off Marseille's frost dates of Mar 15.
Step 1 · Sow
Start seeds indoors
Jan 4 – Jan 25
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Feb 22 – Mar 15
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 23 – Jun 12
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Marseille's 261-day season leaves this much room.
Onion on Marseille'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 15
DEC 1
Common questions
When will onion be ready to harvest in Marseille?
Expect to harvest from around late May (May 23–Jun 12) in Marseille, based on its local frost dates. Confidence 76%.
When should I start onion seeds indoors in Marseille?
Start seeds indoors around early January (Jan 4–Jan 25) in Marseille, based on its local frost dates. Confidence 80%.
When can I transplant onion outdoors in Marseille?
Transplant outdoors around late February (Feb 22–Mar 15) in Marseille, based on its local frost dates. Confidence 84%.
How long is the growing season in Marseille?
Marseille has roughly 261 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 Marseille's frost dates.
Confidence 84/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.