Originating in the Andes regions of South America, potatoes quickly became a staple food in much of Northern Europe, from there spreading to Northern India and beyond. There are many areas of the world, however, that have not embraced this humble vegetable with much enthusiasm, unless it is presented in the guise of french fries.
Potatoes are easy to grow, exciting to harvest and, when eaten minutes after being dug from the ground, have a flavor that it is impossible to experience from those found in stores. Only the tubers which form on the roots are eaten since all other parts of the plant are poisonous, including any tubers which have been exposed to light and have turned green.
Hundreds of varieties exist with colors that vary from red, yellow, russet, white and even purple. Depending on the structure of the starch in the tuber, the texture can be either waxy (good for salads) or floury (preferred for mashed potatoes). Early varieties are harvested when quite small, while others grow more slowly, become large and store well. Likewise, shapes vary from round to oval and finger-like. In ideal conditions, the yield from 2 pounds of seed tubers can be as much as 50 pounds, although I have never managed achieve that.
In Bishop, I have grown Yukon Gold, Red La Soda, Cal White, Purple Majesty and one that is popular in Fish Lake Valley called Victoria. These varieties have all been consistent with satisfactory yields and not been troubled by any obvious diseases or pests; one year, they had aphids, which responded well to a basic horticultural soap which I had to use only once. Anthocyanin – which gives the purple potatoes their pigment – is an antioxidant and present at four times the amount in these potatoes when compared with russet varieties. Although these tubers are a fabulous color when raw, I found that the grayish color once they had been boiled and mashed rather lacked appeal. Judging by the images for mashed potatoes on Google though, perhaps it is my culinary skill that is lacking.
Potatoes grow best in full sun, with some afternoon shade in the hottest places. They are able to produce in a wide range of soils, but prefer a well-dug sandy loam to which rotted compost or manure has been added. If necessary, a nitrogen fertilizer can be mixed into the soil at planting. They can also be grown in grow-bags or large pots with good compost. Potatoes need a regular supply of moisture, as their tubers will become knobby if the plants are allowed to become too dry between watering. The tops will form a soft-stemmed floppy bush about 2 feet high, so make sure that you have enough room.
Seed potatoes are not seeds at all, but small tubers which become available in catalogs and nurseries in early spring. Buy only certified disease-free stock. Do not use eating potatoes from the grocery store, as these are sprayed with a growth inhibitor to stop them from sprouting in storage and will not have been checked for disease. The best seed potatoes are about the size of a large egg, not withered, and with sprouts just showing where the “eyes” (little indentations) are. Before planting, these sprouts should be developed into shoots. Look carefully at the tuber. One end was attached to the parent plant and will show a slight scar which will not have any sprouts nearby, while the other end will have more plentiful potential shoots showing. Place the tubers with the sprouting end upwards – I use an egg carton to keep them separate - and leave them in a bright but cool, frost-free place for a few weeks until the sprouts have grown a little (about the size of a pencil eraser) and small roots appear at their base. Do not let the shoots become long, drawn and white like those potatoes that one finds forgotten in the back of the pantry. Now it is time to plant!
Place early cultivars 4-5 inches deep and 12 inches apart, with the sprout ends uppermost. Maincrop potatoes will produce better if planted 15 inches apart. If your seed potatoes are on the large side, cut them in half longitudinally or cut into smaller 2-oz. pieces, each with an eye. While the cut surfaces may be allowed to dry for a couple of days before planting, I have never had any luck doing this, and the pieces have invariably rotted. Since I use drip irrigation with emitters at 12-inch intervals, I use 12-inch spacing for all varieties. This seems to work just fine, although the maincrop potatoes are a little smaller.
While early April is the usual recommended planting time for Bishop, I have planted on March 3 for the past four years. Since it takes a couple of weeks for the sprouts to emerge, the temperature is generally warmer once they are up. I have been vigilant about covering them on cold nights, since the sprouts are tender and destroyed by even quite slight frosts. Potatoes do usually have some dormant buds kept in reserve, but I just hate losing all that new growth!
As the plants grow, draw up some soil around the stems - no higher than 6 inches - to form ridges along the rows. As needed, add soil or mulch around the plants to prevent the growing potatoes from being exposed to light (which makes them green and unusable). Keep an eye out for any pests or diseases, and use recommended Integrated Pest Management as necessary. In some areas, potato blight can be devastating, as what occurred during the great Irish Potato Famine, which resulted in severe starvation for the population of an entire country. So far, I have seen no hint of blight in Bishop.
Eventually, the plants will produce either purple or white flowers with the typical Solanum structure. At this point, the early varieties can be harvested by digging up the plant. It is usual to use a fork for digging up the roots. No matter what I use or how careful I am, I always manage to spear or chop the prize specimen! These early tubers will be small with a thin delicate skin which does not need to be removed. The flavor will be delicious. Potatoes grow rapidly at this point and can double their size in a week, so they will come to no harm if left a little longer. Maincrop varieties are harvested well after flowering when the tops have died down. Their skins are thicker and, if undamaged, they will store well in a dark, cool dry place.
Overview of types: http://www.potatoesusa.com/products.php?sec=Table-Stock+Potatoes
Integrated Pest Management: http://www.ipm.ucdavis.edu/PMG/selectnewpest.potatoes.html
Container planting demo: http://www.youtube.com/watch?v=vNml1YeDS5M