When to plant cauliflower in Ottawa
Cauliflower is cold-hardy, so every date keys off Ottawa's frost dates of Apr 29.
Step 1 · Sow
Start seeds indoors
Mar 18 – Apr 8
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 26 – May 17
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 25 – Jul 20
Picking runs until conditions turn against the crop.
Step 4 · Second sowing
Autumn / second sowing
Jun 15 – Jun 29
A second window for a fall crop, timed to mature before the first frost.
Step 5 · Second harvest
Autumn crop harvest
Aug 21 – Sep 15
Maturity window for the second sowing.
Window
Days to maturity
60 – 85 d
Ottawa's 161-day season leaves this much room.
Cauliflower 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
APR 29
OCT 8
Common questions
When will cauliflower be ready to harvest in Ottawa?
Expect to harvest from around late June (Jun 25–Jul 20) in Ottawa, based on its local frost dates. Confidence 80%.
When should I start cauliflower seeds indoors in Ottawa?
Start seeds indoors around mid March (Mar 18–Apr 8) in Ottawa, based on its local frost dates. Confidence 85%.
When can I transplant cauliflower outdoors in Ottawa?
Transplant outdoors around late April (Apr 26–May 17) in Ottawa, based on its local frost dates. Confidence 86%.
Can I plant cauliflower in autumn in Ottawa?
Yes — Ottawa supports a second, autumn sowing of cauliflower around mid June (Jun 15–Jun 29), timed to mature before the first fall frost.
How long is the growing season in Ottawa?
Ottawa has roughly 161 frost-free days, which is enough time to grow cauliflower to maturity outdoors.
The rule of thumb
Sow cauliflower 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 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.