When to plant kale in Ottawa
Kale is cold-hardy, so every date keys off Ottawa's frost dates of May 6.
Step 1 · Sow
Start seeds indoors
Mar 25 – Apr 15
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 15 – May 6
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 9 – Jun 29
Picking runs until conditions turn against the crop.
Window
Days to maturity
55 – 75 d
Ottawa's 149-day season leaves this much room.
Kale on Ottawa'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 6
OCT 2
Common questions
When can I sow kale outdoors in Ottawa?
Direct-sow around mid April (Apr 15–May 6) in Ottawa, based on its local frost dates. Confidence 84%.
When will kale be ready to harvest in Ottawa?
Expect to harvest from around early June (Jun 9–Jun 29) in Ottawa, based on its local frost dates. Confidence 76%.
When should I start kale seeds indoors in Ottawa?
Start seeds indoors around late March (Mar 25–Apr 15) in Ottawa, based on its local frost dates. Confidence 80%.
When can I transplant kale outdoors in Ottawa?
Transplant outdoors around mid April (Apr 15–May 6) in Ottawa, based on its local frost dates. Confidence 84%.
How long is the growing season in Ottawa?
Ottawa has roughly 149 frost-free days, which is enough time to grow kale to maturity outdoors.
The rule of thumb
Sow kale 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 Ottawa's frost dates.
Confidence 84/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.