Choose the Best Potatoes

• The volume of starch in a potato determines how well it will endure the canning process and the quality of the water inside the jar. Avoid high-starch spuds, such as russets, because they are more likely to fall apart in the jar during or after the canning process. Excess starch can also cloud the canning liquid and create a gelatinous soup. Choose low-starch potatoes, such as red or Yukon Golds. These are typically thin-skinned and considered to be good boiling potatoes.

Remove the Skin

• Rinse and peel potatoes before you can them. A potato is exposed to botulism spores underground, so the skin is the portion of the potato most likely to carry contaminants. Can whole potatoes only if they are 2 inches in diameter or smaller. Cut potatoes larger than 2 inches into smaller pieces that are uniform in size and shape to promote even distribution in the jars.

Prevent Discoloration

• Before pressure-canning, place the potatoes or potato pieces in an ascorbic acid solution for several minutes to prevent the potatoes from darkening. Look for ascorbic acid products where canning products are sold. To create your own solution, crush 3,000 milligrams of vitamin C tablets and add the powder to 1 gallon of water. Rinse the potatoes under cool running water, then blanch the potatoes in boiling water to remove excess starch. Blanch whole potatoes that are 2 inches in diameter for 10 minutes. Half-inch cubes need only two minutes in the water. Drain and rinse the potatoes.

Fill the Jars

• Place clean canning jars in a pot of boiling water to keep them sterile until you fill them. Handle hot jars with a jar lifter. Fill the jars with the blanched potatoes, leaving 1 inch of head space. Pour fresh boiling water into the jars to cover the potatoes. Do not reuse the water in which you blanched the potatoes, which contains starch that drained from the potatoes while they cooked. Cover the jars with canning lids and secure them with screw bands.

In the Canner

• Follow the instructions for the pressure canner to reach the correct pressure setting for your altitude. The required pounds per square inch of pressure -- the PSIG -- as measured by a gauge may vary from from 11 to 14 pounds, depending on your altitude. Start timing the process when the canner reaches the necessary level of pressure. Process white potatoes for 35 minutes in pint-sized jars or 40 minutes in quart-sized jars. Process sweet potatoes for 65 minutes in pints or 90 minutes in quarts. Remove the canner from the heat once the jars finish processing and allow the jars to cool in the canner. Follow the canner’s instructions for venting and opening the lid after the canner cools to 0 PSIG. Transfer the jars to a cooling rack with a jar lifter to finish the cooling process, which takes about 12 to 24 hours.

Storage and Use

• Remove the screw bands and label the jars with the canning date before storing the potatoes. Canned potatoes remain safe for as long as five years. For best results, use the potatoes within one year. Canned potatoes are suitable for mashed potatoes, potato salad and casseroles, but their water content makes them difficult to fry.