The potato is a non-hardy perennial grown as an annual in Québec.
There are a number of early (less than 120 days), mid-season or late (150 days) varieties. New potatoes are varieties picked before maturity (often early or mid-season), and conservation varieties (late) are harvested at full maturity when the plants wither.
Get certified disease-free potatoes from seed companies or else simply organic ones (non-GMO and non-irradiated) at the market.
Germination and planting
- Get a head start if time allows and germinate your potatoes in an open paper bag placed in indirect sunlight, at a temperature of around 20 °C. This stage is not indispensable, except if you want to make sure your potato isn’t irradiated.
- Wait until the soil is sufficiently thawed and settled (adequately dried out) in the spring, around mid-May. A temperature of 10 °C (day and night) is a good indicator. If frost is forecast, create a little mound of earth around the plant.
- Loosen the soil and dig a trench or a hole 12 inches deep. You can cut the potatoes into a number of pieces, as long as they all have at least two eyes (each eye will produce a seedling) – a precaution to take in case an eye fails to germinate or dries out. Place the potatoes 40 centimeters apart, and cover them with 6 to 8 centimeters of earth.
- Finally, did you know it’s possible to grow potatoes in a pot? Put a little earth at the bottom of a pot and add the potatoes, which you’ll cover to a depth of 6 to 8 centimeters. As they grow, follow the same principle as in ridging by adding earth.
- Water, of course, especially in extremely dry weather.
- Ridge as the plant grows, a few times over the summer (say every 15 days). Start when the foliage reaches 20 centimeters in height.
- Stop all work on the soil when flowering occurs, since you risk breaking the roots and retarding growth. The formation of tubers coincides with flowering.
- Tubers develop at the end of underground stems, known as runners. Tubers can produce chlorophyll and a toxic substance, solanine, if exposed to light. Which is why they need to be blanched (by adding more earth) continually.
- Watch out for the Colorado potato beetle. Adults and larvae eat the leaves. By way of prevention you can spray the plants with a nettle manure and kelp extracts, and rotate by planting in different spots every year. Otherwise, manually crush the orange-colored eggs and drop the larvae and adults in soapy water to eliminate them. The important thing is to reduce the insect population and keep it from eating too much foliage, which would harm tuber production.
- Harvest when the stems turn yellow and wither, taking care not to harm the tubers with your tools.
- Compost what’s turned green.
- Dry your potatoes in the sun for one day and then keep them in the dark in a paper bag at a cool temperature of about 5 °C. You’ll then have potatoes to eat in the winter and can keep some for replanting the following year.
Seed companies with potatoes: Ferme Tournesol, Les couleurs de la terre (Yamachiche), W. H. Perron, Seeds of Diversity