The potato grew wild and now grows to perfection in southwestern Colorado, in the Rocky Mountains, and under similar conditions in the Andes Mountains in South America.

In these districts the winters are cold, and the ground is generally covered with snow from early fall - before the ground freezes - until late in the spring. There is often a heavy blanket of snow until May. In the growing season there are 100 to 110 days between killing frosts. During this period the nights are cool, but there are twelve to fifteen hours of bright, intense sunshine during the day. Occasional light showers of a few minutes' or hours' duration occur, but the total summer rainfall is very small in comparison to the total for the year.

Nothing but the strongest plants and animals live under these conditions, but such grow to the highest perfection and strength. The air is vitalizing and invigorating. Vigorous, healthy people choose it, while debilitated people of low vitality prefer more mild conditions.

Long hours of bright sunshine make the potato in its native home free from disease; and where the tuber is grown under less favorable conditions the ingenuity of man has supplied as nearly as possible the things that nature has furnished in the Rocky Mountain region referred to.

At Prospect Farm, at Redstone, on Crystal River, in the coal fields of western Colorado, potatoes were grown for the camp during the early '80's. This farm was maintained for eight or ten years, then abandoned. Potatoes have grown in this neglected field from year to year without replanting, ever since that time. Under the conditions in this natural home of the potato the growth of the plant is checked by the frosting of the haulm, or top, in the early fall. This stops the rank, watery growth and the tuber ripens in the dry soil. This growth checking seems an essential in the growing of the highest class product, and where frost does not come in time the same effect has been secured by mowing off the tops.

Since potatoes have been grown commercially under similar conditions to those in the home of the wild potato, it has been found that varieties last longer there without "running out" or "changing seed." Old varieties that have become less valuable each year in other districts are revitalized and restored to their original perfection when planted there. The places referred to are the Carbondale district in Colorado; the Twin Falls country and other sections along Snake River in Idaho; and an instance of this reinvigoration is the success of the "Perfect Peachblow" at Mt. Sopris Farm, Carbondale, Col. At Dalmeny Farms, Edinburgh, Scotland, conditions are similar in some particulars, and potatoes live over winter in the ground and produce crops the next year.

While the potato grows best and with the least care from man in its native habitat, it has been adapted to a wide range of climatic conditions. It is successfully grown in practically every country in the temperate zone and in some places under very unfavorable conditions. The potato cul-turists of Europe have originated and adopted cultural methods and moulded varieties to conditions in a most scientific, skilful, and practical way. Potatoes are grown successfully on shifting sands so light that they are thatched with straw to keep the soil from blowing away, and on clay lands so heavy that they require close tiling (underdraining with tiles forty to sixty feet apart) and the most careful, watchful cultural methods.

It is true that there is no place in the temperate zone where potatoes cannot be grown by adding artificially to the natural conditions those things necessary to make the soil and climate approach the natural environment. It necessarily follows, however, that in selecting a place to grow potatoes under ideal conditions some of the mountain valleys of the Rocky or Andes Mountains would be chosen, other things being equal. Latitude and altitude are synonomous as far as they relate to potato conditions when other requirements are the same. There are good districts north at low altitudes and good potatoes grown at high altitudes south or at low altitudes south at sea level where nights are cool and the air is moist.

Maine, New York, Michigan, Wisconsin, and Minnesota are examples of low altitudes north, the Snake River country, the Greeley and Car-bondale districts of high altitudes south, and Santa Rosa, Lompoc, and Salinas on the Pacific coast in California, and southern Great Britain and the Channel Islands of low altitudes at sea level.

These statements as regards north and south refer to the north temperate zone and would be reversed for the south temperate zone.

The sweet potato is another consideration and is described in another chapter.

It is possible that the change in temperature each day, which approximates 30 to 50 degrees, has something to do with the vitalizing of plants, the same as man is apparently invigorated and restored daily in these mountain districts where such changes occur.