When to plant radish in Ottawa
Radish is cold-hardy, so every date keys off Ottawa's frost dates of Apr 29.
Step 1 · Sow
Direct sow outdoors
Apr 23 – May 14
Sow straight into warm, workable soil.
Step 2 · Harvest
Harvest window
May 18 – May 23
Picking runs until conditions turn against the crop.
Step 3 · Second sowing
Autumn / second sowing
Aug 18 – Sep 1
A second window for a fall crop, timed to mature before the first frost.
Step 4 · Second harvest
Autumn crop harvest
Sep 19 – Sep 24
Maturity window for the second sowing.
Window
Days to maturity
25 – 30 d
Ottawa's 161-day season leaves this much room.
Radish 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 can I sow radish outdoors in Ottawa?
Direct-sow around late April (Apr 23–May 14) in Ottawa, based on its local frost dates. Confidence 86%.
When will radish be ready to harvest in Ottawa?
Expect to harvest from around mid May (May 18–May 23) in Ottawa, based on its local frost dates. Confidence 80%.
Can I plant radish in autumn in Ottawa?
Yes — Ottawa supports a second, autumn sowing of radish around mid August (Aug 18–Sep 1), 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 radish to maturity outdoors.
The rule of thumb
Sow radish 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.