Collards · Markham, Ontario, Canada
When to plant collards in Markham
Main outdoor window
17 Apr - 15 May
The window this page is built around.
Timed from last spring frost
1 May
In Markham, on your chosen risk.
Ready to pick
1 Sep - 31 Mar
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 Markham
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.
Start indoors
20 Mar - 17 Apr
Six weeks before your last frost, under cover or on a windowsill.
Sow for overwintering
10-31 Jul
Counting back 89 days from your first frost so the crop matures in time.
Sow direct
17 Apr - 15 May
Two weeks before your last frost.
Transplant
17 Apr - 15 May
Two weeks before your last frost.
Harvest
1 Sep - 31 Mar
Collards through the year
Against the frost risk in Markham
Why these dates
Sow in spring for summer picking or, better, twelve weeks before the first autumn frost for leaves through winter. Pick the lower leaves and the plant keeps rising.
Survives about -10C and sweetens sharply once night temperatures drop below freezing, which is why southern growers treat frost as the start of the season rather than the end.
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. Collards are timed from 6 weeks before that frost for an indoor start, with planting out 2 weeks before it, and this page simply resolves those offsets against the frost date computed for Markham.
The median frost-free season here is 180 days, against 55 to 75 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Markham
Other vegetables to time
Growing collards in Markham
When should I plant collards in Markham?
Aim for 17 Apr - 15 May in an average year. If you would rather not gamble on the weather, wait until 4 May - 1 Jun - by then frost has finished in nine years out of ten.
When will collards be ready to harvest in Markham?
Expect to start picking around 1 Sep - 31 Mar, based on 55 to 75 days to maturity from the planting date calculated for this location.
How much frost will collards tolerate?
Survives about -10C and sweetens sharply once night temperatures drop below freezing, which is why southern growers treat frost as the start of the season rather than the end.