When to plant basil in Calgary
Basil is frost-tender, so every date keys off Calgary's last spring frost of May 23.
Step 1 · Sow
Start seeds indoors
Apr 18 – May 9
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
May 30 – Jun 20
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 29 – Aug 28
Picking runs until conditions turn against the crop.
Window
Days to maturity
60 – 90 d
Calgary's 115-day season leaves this much room.
Basil on Calgary'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 23
SEP 15
Common questions
When can I sow basil outdoors in Calgary?
Direct-sow around late May (May 30–Jun 20) in Calgary, based on its local frost dates. Confidence 82%.
When will basil be ready to harvest in Calgary?
Expect to harvest from around late July (Jul 29–Aug 28) in Calgary, based on its local frost dates. Confidence 74%.
When should I start basil seeds indoors in Calgary?
Start seeds indoors around mid April (Apr 18–May 9) in Calgary, based on its local frost dates. Confidence 78%.
When can I transplant basil outdoors in Calgary?
Transplant outdoors around late May (May 30–Jun 20) in Calgary, based on its local frost dates. Confidence 82%.
How long is the growing season in Calgary?
Calgary has roughly 115 frost-free days, which is enough time to grow basil to maturity outdoors.
The rule of thumb
Sow basil 6–8 weeks before your last spring frost; plant out 2–3 weeks after it. Every date on this page is derived from that rule and Calgary's frost dates.
Confidence 82/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.