This past week, the Saskatchewan Horticultural Association posthumously honoured Jackie Bantle with a Lifetime Achievement Award for her work in promoting and advancing horticulture in Saskatchewan. She was our vegetable specialist. Below is an article she wrote for us in 2007. If you have not already harvested your potatoes, here are some tips on the harvest as well as storing your tubers.
Potatoes, one of the most popular vegetables grown in Saskatchewan, can be harvested at any time through the season, as long as they’re large enough to wash and cook. But tubers harvested from “green” growing plants have immature skins that are easily rubbed off through washing, providing little protection in storage. Those destined for long-term storage need to be cured.
Skin set in potatoes occurs when the potato top has dried or been removed and the tubers have stopped growing. At this point, the skin toughens up to provide a protective layer against disease and insects during storage. Once the tops have frozen off or been removed, the tubers can remain in the soil as long as the surrounding soil temperature is at or above 0 C. Typically, well-hilled potatoes can withstand numerous frosts down to –3 C as long as temperatures reach at least 10 C during the day. Frosts that go to –4 C may damage some tubers. If temperatures are predicted below –4 C, tubers should be dug as soon as possible.
Potato harvesting is best done on a cool, dry day and those dug in the fall are usually cool. If that temperature can be maintained or lowered going into storage, water loss will be reduced. First, remove excess soil from the tuber. Avoid washing them, as this can increase bruising or skin damage. Damaged or wet tubers should be placed in a dark area with good airflow where the average temperature is 10 to 15 C to encourage healing and drying.
Avoid drying tubers in the sun. Sunlight warms up the tubers and encourages the production of glycoalkaloids that give potatoes a bitter flavour, can turn the skin and flesh green, and at high levels are poisonous.
After about one week at 10 to 15 C, potatoes should be moved to a dark storage area at 2 to 3 C and 80 to 90 per cent relative humidity. Placing them in perforated plastic bags in the fridge is ideal for long-term storage. Root cellars provide adequate storage for a shorter period, but most root cellars have higher temperatures and lower humidity than is ideal. Covering a potato stack with perforated plastic and installing a mini air conditioner can help.
Once the potatoes are in storage, other problems can occur. Potatoes that have tiny black spots throughout their flesh (indicating dead tissue) have usually been exposed to inadequate air during their growth, often caused by extended periods of flooding. Also ensure there is adequate air exchange in storage.
Potatoes that break down and rot during storage may be affected by a bacterial disease that has been carried over from the seed or soil. Avoid this problem by using new seed potatoes each year and rotating vegetables within your garden. Potatoes harvested from diseased plants will not last as long in storage as those from healthy plants.
Many gardeners experience mushy potatoes after boiling. Several factors can influence texture. Red potatoes and some white varieties have been bred for boiling, while the higher soluble solid content in russet types is excellent for baking but often results in mushy boiled potatoes. Red potatoes that have been stressed during the growing season from too much heat or too little water may also have a mushy texture when boiled.
This winter, why not treat yourself to homemade French fries from your garden potatoes? Potatoes high in sugars tend to be dark in colour when fried. For lighter fries, condition the potatoes by warming them up to 15 C (in the dark) for several weeks. This encourages the sugars to convert to starch, consequently producing a lighter-coloured fried potato.
Remember, vegetables are living organisms and only the best produce will provide excellent quality in storage, long after the leaves have fallen from the trees.
This column is provided courtesy of the Saskatchewan Perennial Society (SPS; saskperennial@hotmail.com). Check our website (www.saskperennial.ca) or Facebook page (www.facebook.com/saskperennial) for a list of upcoming gardening events
