Shirley poppy · Edmonton, Alberta, Canada
When to sow shirley poppies in Edmonton
Main outdoor window
15 Apr - 6 May
The window this page is built around.
Timed from last spring frost
13 May
In Edmonton, on your chosen risk.
Ready to pick
14 Jun - 4 Jul
If you plant at the start of the window.
The average last frost. Half of all years are later than this.
Step by step in Edmonton
Each window is a range, not a single day. Earlier in the range buys you a longer season; later in it buys you a safer one.
Sow direct
15 Apr - 6 May
Four weeks before your last frost.
In flower
14 Jun - 4 Jul
Shirley poppies through the year
Against the frost risk in Edmonton
Why these dates
Sow direct four weeks before the last frost, on the surface with no covering - the seed needs light to germinate and disappears if raked in. Sowing onto snow or frosted ground works well and spaces the seed for you. It cannot be transplanted at any size, so sow where it is to flower.
Hardy to about -12C and germinates in cold soil, so it is a natural for autumn or late-winter sowing. Ends abruptly in the first real heat of summer.
Seed packets and extension guides express timing as weeks either side of the last spring frost, because that is the only reference point that travels. Shirley poppies are timed for direct sowing 4 weeks before it, and this page simply resolves those offsets against the frost date computed for Edmonton.
Hardiness is not the obstacle here. Edmonton is zone 4a, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.
The median frost-free season here is 137 days, against 60 to 80 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Edmonton
Other flowers to time
Growing shirley poppies in Edmonton
When should I plant shirley poppies in Edmonton?
Aim for 15 Apr - 6 May in an average year. If you would rather not gamble on the weather, wait until 24 Apr - 15 May - by then frost has finished in nine years out of ten.
When will shirley poppies be ready to harvest in Edmonton?
Expect to start picking around 14 Jun - 4 Jul, based on 60 to 80 days to maturity from the planting date calculated for this location.
How much frost will shirley poppies tolerate?
Hardy to about -12C and germinates in cold soil, so it is a natural for autumn or late-winter sowing. Ends abruptly in the first real heat of summer.