Potatoes can be divided into two categories: waxy potatoes and starchy potatoes. Though waxy potatoes can come in red and white varieties, new red potatoes are the most popular. Russet potatoes are the most popular starchy potatoes. Waxy potatoes have a much higher moisture content and a different cell structure than starchy potatoes. Waxy potatoes are best for boiling, pan frying, and canning. They will hold their shape well in water and take abuse in the frying pan without coming apart. Russet potatoes are light and fluffy and are perfect for baked potatoes.
For potato salads: Use waxy potatoes for those salads calling for boiled potatoes. For recipes calling for baked potatoes, you may use either–though chunks of russet potatoes tend to come apart if they are stirred too much.
For home fries: Use waxy potatoes. They hold together in the frying pan and the higher moisture content is desirable.
For French fries: For deep frying, we much prefer starchy potatoes. Russets make tender fries.
For oven fries: Russets will work well for oven fries since they are usually baked without stirring. They are dry and require a basting of oil. New potatoes can be used.
For mashed potatoes: Starchy russets are usually the choice for mashed potatoes. They mash up smooth and creamy where waxy potatoes hold together and are grainier and with a higher water content.
How long will potatoes keep?
Waxy potatoes with their high water content are best if used within a few days of purchase.
Russets can be kept much longer. In Idaho, potatoes are kept through the winter in cellars that are temperature controlled and humidity controlled. The ideal temperature is 35 to 40 degrees and humidity at 80 to 90 percent. The closer you can replicate those conditions, say in a shed or garage, the longer your russets will last. Fluctuating temperatures may cause potatoes to sprout.
Beyond reds and russets
Specialty potatoes are becoming more popular. There are literally hundreds of varieties grown in the US though most are not discernable to the grocery store shopper.
Yukon Gold potatoes are excellent and are now readily found in many stores. Yukon Gold is an attractive, yellow-fleshed, potato that is suited for baking, salad and soup. It may be used in French frying but is not generally used for such. The light yellow coloring of the flesh of a Yukon Gold potato gives the illusion that it is pre-buttered.
Blue or purple potatoes are now found in many stores across the nation. There is a great deal of variety in these potatoes, some with only a blue skin and many with a blue flesh. Even with the blue flesh, they taste like potatoes, often described as rich and nutty. Some have enough starch to make them good for mashing but most are moist and waxy, perfect for an unusual potato salad.