When to plant onion in Edinburgh
Onion is cold-hardy, so every date keys off Edinburgh's frost dates of May 1.
Step 1 · Sow
Start seeds indoors
Feb 20 – Mar 13
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 10 – May 1
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 9 – Jul 29
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Edinburgh's 170-day season leaves this much room.
Onion on Edinburgh'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
MAY 1
OCT 18
Common questions
When will onion be ready to harvest in Edinburgh?
Expect to harvest from around early July (Jul 9–Jul 29) in Edinburgh, based on its local frost dates. Confidence 74%.
When should I start onion seeds indoors in Edinburgh?
Start seeds indoors around mid February (Feb 20–Mar 13) in Edinburgh, based on its local frost dates. Confidence 78%.
When can I transplant onion outdoors in Edinburgh?
Transplant outdoors around early April (Apr 10–May 1) in Edinburgh, based on its local frost dates. Confidence 82%.
How long is the growing season in Edinburgh?
Edinburgh has roughly 170 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 Edinburgh's frost dates.
Confidence 82/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.