Why is one potato fluffy in A MASH but another still firm in the salad? The cause of your confusion is that you think of potatoes as just potatoes: a single basic ingredient. But in fact each kind have its own character, an inner structure that requires matching task.
That’s where right potato for the job enters the picture. It’s all about texture, and starch content. Potatoes falls into two major categories, those that are starchy (the ones to use in baking) and those that are waxy (best for salads or soups instead of mashing).
The Right Potato for Each Job
The higher the moisture content, the lower the starch; waxy potatoes, like Red Pontiac or Red Norland varieties, maintains their cell structure during cooking, retaining shape in soups, salads, or gratins. Stick one of these guys in food processor, and you’ll wind up with something closer to glue than mashed potatoes. Why? Because cellular structure doesn’t break down effectivly.
At the other extreme, starchy potatoes; like the Kennebec or Russet Burbank… Has a dry, mealy flesh. This flesh breaks down into a feather-light consistency that work well for making crisp fries or baked potato. And, of course, they soak up milk and butter like sponges, making them right at home with comfort foods.
In middle range, there are all-purpose golds like Yukon Gold or Yukon Gem, they has enough starch to break down a bit into creamy mash, but enough structure to roast without disintegrating. That’s what makes these types workable for so many purposes in the home kitchen. One bag will get you through just about anything, creating less waste and making shopping easier. It’s the happy medium between too-soft than too-firm.
Timing is everything with potatoes, and growing them gets more complicated here. The earlier ones, like Red Norland, reach maturity in about seventy-five days; they don’t keep very well but are ready to be dug as tender new potato when their vines is still green. Later varieties like the Russet Burbank needs about four months plus a frost-free period to develop thick skins. These skins then keeps the flesh good and safe during winter storage. In short-season area, you’ll likely harvest green, bitter tubers that haven’t cured propery if you plant late varieties. Most home gardeners loses their crop in storage.
Potatoes are living things; even after being harvested, they keeps right on respiring. To remain dormant, potatoes requires a cool (not refrigerator-cold) and dark location that’s also very humid. Too-warm temperatures causes them to shrivel, or worse, sprout. Too-cold temperatures turns their starch into sugar, so when cooked they will be sweet rather than starchy, with uneven frying results. So the best temperature range is small, just slightly warmer then freezing. A root cellar or a cool basement would of been better than a kitchen counter, then.
While the colorful types (Purple Majesty, for example, or Adirondack Blue) makes a great visual statement, don’t get distracted by appearance; these are all-purpose potatoes. The pigment they contain, anthocyanins (holds up well in roasts and chips).
Treat your potatoes as any vegetable: Plant only certified seed potatoes, not those of the grocery store variety, which may be treated against sprouting. That gives your garden a fighting chance. Treat potatoes with respect; they don’t like to do things that is against their nature.
You can’t get a starchy one to stay firm; you can’t get a waxy one to behave starchily. If you use them correctly in each application, your fry will be crispy, your salad will have heft, and your mashed spuds won’t turn to glue. It is not magic, just botany with a dash of common sense.