After all your work of planting and caring for your potato plants, here's how to get the most from your harvest.
The earliest or "new" potatoes of the season are a treat not to be missed. They're small, round, smooth and delicious. When you think you have early potatoes big enough to eat, reach into your early hills, feel for the best-sized spuds and ease them out. The plants keep right on growing and producing more.
During seasons when the soil has been quite moist (which makes hunting by hand tougher), dig up entire plants, harvest all the baby potatoes you can find and put the plants back in the earth. They'll survive this rude transplant and produce quite a few more potatoes. But working fast is important; freshly dug potatoes shouldn't stay in the sun very long.
The best tool for digging is a 5- or 6-pronged fork. Dig down under a hill, then lift up. The dirt falls between the prongs, and you're left with a forkful of potatoes. There's less bending this way, too.
In the North, harvest the main storage crop in September, when the days are getting cool and frost isn't far off. That's when the plant tops are dying and sending the last of the vines' energy underground to the tubers.
If you'll be storing most of the late potatoes, wait for the best weather conditions possible before digging them up. Choose a warm, dry day after a period of little or no rain. Cloudy days are even better, since too much light turns newly dug potatoes green, changing their flavor.
After you dig a few hills, you'll discover that all the potatoes in a hill are at pretty much the same level. Once you figure out how deep to dig your fork, you won't injure as many potatoes. Of course, if you've got some beginners on the work crew, there'll be a few spiked spuds. Put them aside for the evening meal; they won't keep. A pointed shovel does a good job, too. You can dig deep enough next to a hill to raise the entire hill at one time.
Be gentle. Try not to rough up or bump the potatoes. Each bruise lowers the storage quality and appearance of the tuber.
After the Harvest
Leave the potatoes outdoors for an hour or so to dry. During that time most of the soil stuck on them should also drop off. There's no real need to brush the tubers, although some people use a very soft brush gently to take off clumps of dirt. Don't wash the potatoes; it's hard to get them really dry afterward.
Put the potatoes in the dark after they've dried in the open for a short time. Don't leave them in burlap bags or other containers where light can penetrate and start them greening.
If possible, storage potatoes should have a short drying or "curing" period of one to two weeks after the harvest. Curing allows any slight cuts or bruises on the potatoes to heal rapidly. Keep the tubers in a dark place with temperatures around 55° to 60° F with high humidity of up to 85 or 95 percent.
After a curing period, move the potatoes to a much cooler, dark place for winter storage. Experts recommend 35° to 40° F with moderate humidity and ventilation. If these standards are met in your basement or root cellar, you can expect mature potatoes to store for up to eight months. Higher temperatures will mean quicker sprouting and shriveling.
Because potatoes have to breathe in storage, a root cellar needs good air circulation The potatoes are still carrying on normal life processes, using oxygen to heal bruises and cracks and giving off carbon dioxide, heat and moisture. Good air circulation in the storage room helps this continuing process. A good way to store potatoes is in bins with slatted sides and bottoms; however, don't pile them higher than 6- to 8-inches tall.
Occasionally, potatoes turn "sweet" during storage. This happens because potatoes convert a certain amount of starch to sugar, which is used up in the "breathing" process. When the tubers are stored in cool root cellars, the breathing slows down and they don't use up all the sugar they produced. Occasionally, this extra sugar gives the potatoes a sweet taste if they've been taken directly from cool storage and cooked. However, this is rarely a problem. If your potatoes sweeten, just bring a week's supply out of storage at one time and keep them in a warmer spot. The extra sugar will revert to starch -- a process experts call "reconditioning".
A Note on Green Potatoes
When potatoes are exposed to light their skins start to turn green -- a sign that a toxic substance called solanine is developing. This occurs if potatoes aren't fully covered by soil while they're growing, if you leave them in the sun for too long after the harvest, or if they aren't stored in complete darkness. Potatoes you buy from the supermarket also turn green if they aren't stored in a dark place.
Because solanine is slightly toxic, it's possible to get sick if you have a large helping of greened potatoes. Peeling or cutting away green sections before cooking usually eliminates the problem, as most of the solanine is located in the spud's skin.
This article is a part of our Vegetable Gardening Guide for Potatoes and Sweet Potatoes / Harvesting.