Garlic · Markham, Ontario, Canada
When to plant garlic in Markham
Main outdoor window
16-30 Sep
The window this page is built around.
Timed from last spring frost
1 May
In Markham, on your chosen risk.
Ready to pick
14 May - 13 Jun
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.
Plant cloves
16-30 Sep
Four to six weeks before your first frost, so roots form before the ground cools.
Harvest
14 May - 13 Jun
Garlic through the year
Against the frost risk in Markham
Why these dates
Plant four to six weeks before your first autumn frost so roots establish before the ground cools. Hardneck types require a genuine cold period and will not bulb properly in mild-winter climates.
Survives -20C under mulch. Hardnecks need six to eight weeks below 10C to form cloves, making this a crop that actively requires winter.
Garlic are anchored to the first autumn frost rather than the last spring one, so the planting window on this page counts backwards from the end of the season in Markham instead of forwards from its start.
The median frost-free season here is 180 days, against 240 to 270 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 garlic in Markham
When should I plant garlic in Markham?
Aim for 16-30 Sep in an average year. If you would rather not gamble on the weather, wait until 1-15 Sep - by then frost has finished in nine years out of ten.
When will garlic be ready to harvest in Markham?
Expect to start picking around 14 May - 13 Jun, based on 240 to 270 days to maturity from the planting date calculated for this location.
How much frost will garlic tolerate?
Survives -20C under mulch. Hardnecks need six to eight weeks below 10C to form cloves, making this a crop that actively requires winter.