Potatoes

Humans domesticated potatoes in the cool, arid high plateaus of the
Andes where annual rainfall averages 8 to 12 inches. The species
finds our dry summer quite comfortable. Potatoes produce more
calories per unit of land than any other temperate crop. Irrigated
potatoes yield more calories and two to three times as much watery
bulk and indigestible fiber as those grown without irrigation, but
the same variety dry gardened can contain about 30 percent more
protein, far more mineral nutrients, and taste better.
_Sowing date:_ I make two sowings. The first is a good-luck ritual
done religiously on March 17th--St. Patrick's Day. Rain or shine, in
untilled mud or finely worked and deeply fluffed earth, I still
plant 10 or 12 seed potatoes of an early variety. This provides for
summer.
The main sowing waits until frost is unlikely and I can dig the
potato rows at least 12 inches deep with a spading fork, working in
fertilizer as deeply as possible and ending up with a finely
pulverized 24-inch-wide bed. At Elkton, this is usually mid-to late
April. There is no rush to plant. Potato vines are not frost hardy.
If frosted they'll regrow, but being burned back to the ground
lowers the final yield.
_Spacing:_ I presprout my seeds by spreading them out in daylight at
room temperature for a few weeks, and then plant one whole,
sprouting, medium-size potato every 18 inches down the center of the
row. Barely cover the seed potato. At maturity there should be
2[f]1/2 to 3 feet of soil unoccupied with the roots of any other
crop on each side of the row. As the vines emerge, gradually scrape
soil up over them with a hoe. Let the vines grow about 4 inches,
then pull up about 2 inches of cover. Let another 4 inches grow,
then hill up another 2 inches. Continue doing this until the vines
begin blooming. At that point there should be a mound of loose,
fluffy soil about 12 to 16 inches high gradually filling with tubers
lushly covered with blooming vines.
_Irrigation:_ Not necessary. In fact, if large water droplets
compact the loose soil you scraped up, that may interfere with
maximum tuber enlargement. However, after the vines are a foot long
or so, foliar feeding every week or 10 days will increase the yield.
_Varieties:_ The water-wise gardener's main potato problem is
too-early maturity, and then premature sprouting in storage. Early
varieties like Yukon Gold--even popular midseason ones like Yellow
Finn--don't keep well unless they're planted late enough to brown
off in late September. That's no problem if they're irrigated. But
planted in late April, earlier varieties will shrivel by August.
Potatoes only keep well when very cool, dark, and moist--conditions
almost impossible to create on the homestead during summer. The best
August compromise is to leave mature potatoes undug, but soil
temperatures are in the 70s during August, and by early October,
when potatoes should be lifted and put into storage, they'll already
be sprouting. Sprouting in October is acceptable for the remainders
of my St. Pat's Day sowing that I am keeping over for seed next
spring. It is not ok for my main winter storage crop. Our climate
requires very late, slow-maturing varieties that can be sown early
but that don't brown off until September. Late types usually yield
more, too.
Most of the seed potato varieties found in garden centers are early
or midseason types chosen by farmers for yield without regard to
flavor or nutrition. One, Nooksack Cascadian, is a very late variety
grown commercially around Bellingham, Washington. Nooksack is pretty
good if you like white, all-purpose potatoes.
There are much better homegarden varieties available in Ronniger's
catalog, all arranged according to maturity. For the ultimate in
earlies I suggest Red Gold. For main harvests I'd try Indian Pit,
Carole, German Butterball, Siberian, or a few experimental row-feet
of any other late variety taking your fancy.