When to Harvest Potatoes on the Prairies
Dead vines, set skins and a mild day: how to time the dig in Alberta, Saskatchewan and Manitoba.
When to harvest potatoes on the Prairies comes down to the vines and the weather. The Government of Saskatchewan says potatoes are ready once the vines have been completely dead for at least 7 to 14 days, which gives the skins time to set.
Temperature matters on the day too. The same source warns that potatoes dug when they are cold bruise easily, and that after a frost they should not be dug until the ground has thawed.
Prairie potato harvest at a glance: Wait until the vines have been dead for 7–14 days so the skins set. Dig on a mild day, not when the tubers are cold, and never in frozen ground. Cure in the dark for about two weeks, then store dark and cold, near 4°C, with high humidity.
Growing potatoes elsewhere? See When to Harvest Carrots for carrot and root-crop timing across Canada.
Prairie Frost Dates
| City | Zone | Average First Fall Frost |
|---|---|---|
| Lethbridge | 4b | Sep 27 |
| Medicine Hat | 4b | Sep 22 |
| Calgary | 3b | Sep 21 |
| Red Deer | 3b | Sep 13 |
| Edmonton | 4a | Sep 23 |
| Regina | 3a | Sep 17 |
| Saskatoon | 3a | Sep 12 |
| Prince Albert | 2b | Sep 8 |
| Brandon | 3a | Sep 15 |
| Winnipeg | 3a | Sep 20 |
Frost dates and zones from this site’s data.
Dead Vines, Set Skins
The Government of Saskatchewan: ready once the vines have been completely dead for at least 7 to 14 days. The University of Massachusetts adds that letting skins mature in the field is one of the main ways to cut storage rot. Test one hill: rub a tuber with your thumb, and if the skin slides off it needs more time.
Pick the Day
The Government of Saskatchewan advises never digging when the tubers are colder than 7°C (45°F) or warmer than 18°C (65°F) inside, since cold tubers bruise and hot ones rot more easily, and not digging after a frost until the ground has thawed. In practice, choose a mild, dry day in September.
Curing and Storing at Home
The University of Minnesota says to cure potatoes at 10–15°C (50–60°F) for 14 days, then store them dark, cold and moist; it expects about six months. The Government of Saskatchewan stores table potatoes at 4°C (40°F) and 90–95% humidity. Keep them in the dark so they do not turn green, and store only sound tubers.
How Much Frost the Tubers Take
The University of Saskatchewan gives the numbers behind the frost warning. A frost down to about −1°C kills potato tops but should not freeze the tubers. Nights below about −3°C may start to freeze tubers, which can lead to rot if they go into long storage.
Its storage advice: about 4°C at 90–95% humidity with good airflow, in the dark, because light turns potatoes green and bitter. Knock off loose soil but do not scrub tubers you plan to store, store only undamaged ones, and keep apples away, because their ethylene makes potatoes sprout.
Frequently Asked Questions
When should I dig potatoes on the Prairies?
Once the vines have been completely dead for 7 to 14 days, on a mild day, according to the Government of Saskatchewan.
Can I dig potatoes after a frost?
Not until the ground has thawed. The Government of Saskatchewan warns that potatoes dug from frozen ground are prone to damage and breakdown in storage.
How do I know the skins have set?
Rub a tuber with your thumb. If the skin slides off, leave the rest in the ground a little longer.
Do potatoes need to be cured?
Yes. The University of Minnesota cures them at 10 to 15°C for 14 days before storage, which heals small wounds.
What temperature should I store potatoes at?
About 4°C with high humidity, in the dark, according to the Government of Saskatchewan.
Why did my stored potatoes turn green?
Light. Store potatoes in the dark.
Sources
- Government of Saskatchewan, Ministry of Agriculture — Potatoes
- University of Minnesota Extension — Harvesting and storing home garden vegetables
- Environment and Climate Change Canada — Canadian Climate Normals (the frost dates in the tables, read from this site’s frost data)
- University of Saskatchewan, Gardening at USask — Potatoes