|My Yukon Gold potatoes|
I planted three different kinds and had the best results with "Yukon Gold"; the "Red Norland" faded early and didn't produce very much; the "Goldrush Russet" had the strongest plants but produced small tubers.
You should harvest the potatoes after the top plants die off. The autumn frost creates this normal cycle. Leaving the potatoes in the ground for a few weeks after the dieback is no problem as long as you harvest before heavy rains come. This time in the ground allows the skins to thicken which increases the time they can later be stored. Potatoes in saturated soil can quickly rot.
Digging them up is the hardest part of the harvest. You can't pull the plant out with potatoes attached; the stem and leaves tear off leaving the tubers in the ground. The objective is to turn over the soil and pick up the intact crop. You can carefully use a shovel, but you run the risk of slicing through some of the potatoes. Or you can use a garden fork as I did and skewer more of them than you'd prefer. Either way you'll probably lose some of the big ones.
There are methods of growing potatoes other than in soil. Gardeners around the world have had success by growing them in straw. You plant the "seed potato" (not really a seed, but a piece of a potato with an eye) shallowly in the soil and as it grows you cover it with straw. You keep the straw moist and add more through the season as the plants grows. It's important that the tubers stay protected from the sun. When it comes time to harvest, you just pull back the straw and easily claim your reward.
After the potatoes are harvested they need to cure for one to two weeks. If you bruised or cut some of them as I did, temperatures around 70 degrees during this period will aid in healing the wounds. If you live in an area with good weather after the harvest you can leave the potatoes in little piles on the ground and let the air circulate around them. Cover the piles with a cloth or burlap to protect them from the sun and bring them in or put them under a sturdier cover if rains come. We have both rain and freezing weather in the forecast so I put my harvest in paper bags in the pantry. In a few weeks I'll begin using them and handing out sample bags to friends and family.
As you know from the bags of potatoes you buy in the market, they store well for a long time. The key is to keep them in a cool, dark place. They also prefer a humid environment during storage. If you store them too long they may shrivel and begin to sprout from the eyes. You can still eat them, but the texture may change. It's best to eat them before they reach that point.
Potatoes can be quite susceptible to disease and pests, particularly the Colorado potato beetle. They can defoliate plants quite quickly. Some potato varieties offer some resistance to pests and disease. Many pesticides are available, but potatoes are among the easier plants to grow organically. If you see the pests you can pluck them off. Rotating your crops and growing your potatoes in a different plot each year will help reduce disease problems.
The success with potatoes means that I'll grow them again. They were surprisingly easy. Once planted they only required regular watering. Next year I just may experiment with the straw method. I grew the three varieties I did because they were packaged together in an inexpensive box at a local garden center. Over the winter I'll do a little more research and try to select the best varieties for my area. I'll let you know what I find out.