How I start the crop
Everytime I harvest a potato crop, I set aside the nicest looking tubers of my preferred size. These will become my seed potatoes for the next crop. Size depends upon the variety, so I can't say "baseball size" or "large goofball sized" because each potato type varies. But I'm looking for a tuber that has the desired characteristics (color, shape) and is medium large or large for that variety. Plus importantly, the tuber came from a plant that produced other large tubers, was productive, and didn't have any detrimental traits. Even though potatoes are vegetatively reproduced, the plants do indeed vary.
I also will plant all those under sized, odd shaped, greened tubers that happen with any potato crop.....but only if I happen to have free space that I'm not using for something else. This usually means newly opened ground that I'm getting ready to turn into a garden bed, or some otherwise unused out-of-the-way spot. Sometimes it means the beds along the street where people might steal some of the crop. Why? Growing a crop, any crop, helps improve newly opened soil. And if I'm going to lose veggies to theft, it might as well be something I won't get upset about. (Actually to date I haven't had anything stolen.) And I can use whatever potatoes that happen to grow to feed the livestock.....or ourselves if there happens to be big enough tubers under those plants. But I won't save seed potatoes from these type plants. I don't want to accidently be selecting for small or mishappen tubers.
Preparing the bed
I will remove the previous crop residue and coarse mulch, but leave the partially decomposed mulch in place. I'll then top dress the bed with a little rabbit manure, an inch layer of compost, a dusting of coral sand, lava sand, burnt bone, and urine (or manure tea) treated biochar if I have it. I'll then lightly till it in, using a cultivator type lightweight tiller that goes down about 6 to 8 inches. For potatoes, I normally don't add wood ashes.
Planting the seed potatoes
Everybody has different ideas about the best way to plant potatoes. Actually, this crop is quite flexible. My preferred method is to plant the tubers shallow, about 2 inches below the surface of a freshly tilled bed. I'll space them 12" apart in 2 to 3 rows in my 42" wide beds. With fingerlings and small planted varieties, I can do three rows. Most standard potatoes I plant just two rows. I then cover the soil lightly with grass clipping mulch. A few weeks later I'll be able to add more mulch as the plants start to grow. I'll keep adding more light layers of mulch. The goal is to keep any surface tubers from seeing the sun, and thus greening.
One interesting tidbit that I do. I cut a notch into the seed potato tuber so to mark it. Usually I simply cut off a slice from one side. If this mother tuber survives to harvest time, I want it to be easily recognized for what it is, the mother tuber. I don't want to accidently mix it in with the harvested fresh tubers.
When to harvest. Everybody asks me that and they guess wrong about how I do it. Everybody says to wait for the plants to die back. Well, that doesn't happen here. Plus if I try to wait that long, the mice find the potatoes and eat them. I guess they give off a yummy odor once the tubers are mature. In the beginning of my gardening efforts here, I lost plenty of potatoes to mice before I finally figured out when to harvest my crop.
I harvest when the plants look "tired" or spent. They tend to lose their glossy, vibrant, lush look. The foliage gets a bit dull and droopy, then gets yellowish or bronze. The plants aren't as perky looking, for many varieties that means after two months. For others, it's three months or a tad more. But the plants will tell me. As I said, waiting until they die back doesn't work here, but that's probably is good way to do it in most of the mainland USA.
The first thing I will harvest is any tuber that is exposed to light. I'll go through the bed and remove them and set them aside. These tubers have greening issues and I don't wish to eat the green parts. So these will be eaten first (cutting off the green part) or set aside for using as seed potatoes. Next step, I will pull the plant out and observe if the plant was an exceptional producer and if there are good tubers to use for the next crop. I'll select my seed potatoes and set them aside. Now I'll harvest all the rest of the tubers that are eating size. Finally I'll pick up all the mishappen or undersized tubers, and any "mother tubers" that survived. In some varieties the "mother tuber" rots away, but sometimes it is still there at harvest time. They go into the livestock feed bucket to be cooked along with the extra smalls and odd shaped taters that I don't replant. Any overly green tubers go into the compost bin along with the spent plants.
I like using grass clipping mulch with this crop. It allows me to tuck the mulch around the plants easily. And I can apply it as thickly as needed to prevent tubers from reaching the light, thus turning green. I'm not always successful in getting enough mulch applied, but I try. I don't use the chicken pen litter as a mulch for potatoes. It's too high in nitrogen for this crop.
I'm aware that this crop prefers even soil moisture. For me that means irrigating as needed before the soil dries out, not waiting until things are dry then bringing out the water buckets & hoses.
By observation I learned that potatoes are a shallow crop. They don't need deep soil. In fact, they don't make tubers down deep. So growing them in a trashcan has no advantage over using a half barrel. The tubers will be up near the soil surface in either container. I find most of the tubers in the top 6 inches, but some can be 8 inches down for some varieties. I've successfully produced potatoes in only 3" of soil. That may sound amazing but it's true. Some of my garden beds are quite shallow, but by planting the seed potatoes as deeply as possible and right on top the pahoehoe lava, then using a thicker than usual mulch, I can get a normal sized crop of spuds. There are a number of crops I can grow in only 2"-3" of soil, and potatoes is one of them.
...overcrowding. If planted too close, there will be less good sized tubers. So I don't space them closer than 12 inches.
...hollow heart. The only time I've seen hollow heart is during a year that alternated with heavy rains and dry spells. I suspect it has to do with inconsistent soil moisture.
...scab. I often saw some degree of scab when I first started growing potatoes here, but for the past several years I haven't had a problem. Whatever I'm doing, I'm apparently doing right. And I withhold wood ash, which I think contributes to scab in some way. Plus no chicken pen litter is used on potatoes.
...ring rot. Again when I first started growing potatoes I saw some tubers with this, but now I'm not seeing it at all.
...flea beetles. My worst potato problem. These little pests can really damage the plants. To date, I've had problems controlling these insects. If I experience flea beetles, then I will change locations for the next crop, hoping to find a spot where they won't find my potatoes for awhile. Another thing I've done is to plant radishes near by and use them as a catch crop. Flea beetles seem to prefer radishes, various Chinese greens, and beets. And the third thing I can do is to use a good amount of compost when starting out, giving the young plants an good boast for growing rapidly. Aggressively growing plants seem to have more tolerance of the flea beetles. And finally, I've learned that I need to be right in top with it when it comes to flea beetles. Otherwise the infestation gets quickly so far out of control that there is little I can do without resorting to chemical pesticides.
Happily I don't have the Colorado potato bug here. I find that amazing, since we seem to get just about every other crop damaging insect that comes along.
Types of Potatoes I Grow
I like growing all sorts. White, yellow, red, pink, purple. And different sizes and shapes : fingerlings, boilers, bakers, round, blocky, long and skinny. It's fun. The only type that I don't do great with are the russet type bakers. They never get real large, but they do grow ok otherwise.
Varieties I like growing best:
Dark Red Norland
But I grow plenty of other types too. Irish Cobbler does well. Frankly, just about every variety does at least "ok", but some I'd say are more outstanding than others. Plus the weather has a big factor, so by growing it's if different varieties, I'm guaranteed to get a potato crop in spite of the year's growing conditions.