The potato is a perennial plant, not hardy in Québec, that is grown as an annual.
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 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 minimum temperature of 10 °C (day and night) is a good indicator. If frost is forecast and potatoes have already been planted, create a little mound of earth around the plant.
- Loosen the soil and dig a trench or a hole 12 centimeters deep. You can cut the potatoes into a number of pieces, as long as they all have at least two eyes or buds (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.
- Did you know it’s possible to grow potatoes in a pot? Put a little earth at the bottom of a large pot and add the potatoes, which you’ll cover to a depth of 6 to 8 centimeters. As the plants grow, add earth to keep the tubers well covered.
- Water, of course, especially in dry weather.
- Hill up soil around the plants as they grow to protect the tubers (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. That is why soil is hilled up around the plants continually.
- Watch out for the Colorado potato beetle. Adults and larvae eat the leaves. To reduce infestations, practice crop rotation by planting potatoes in different spots every year. Manually crush the orange-colored eggs found on the underside of the leaves 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 leaves turn yellow and wither, taking care not to harm the tubers with your tools.
- Compost what’s turned green.
- After the potatoes have been harvested, delicately remove the excess soil with your hands. It is important not to damage the skin of the potatoes. Dry them for one day-before storing them. If the potatoes are placed in the sun during drying, cover them with a cloth. Keep them in the dark during the entire storage period, 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.
Some seed companies selling seed potato tubers: Tourne-Sol Cooperative Farm, Les couleurs de la terre, W. H. Perron, Seeds of Diversity.