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.

Rutabagas

Rutabagas have wonderfully aggressive root systems and are capable of growing continuously through long, severe drought.  But where I live, the results aren’t satisfactory.  Here’s what happens.  If I start rutabagas in early April and space them about 2 to 3 feet apart in rows 4 feet apart, by October they’re the size of basketballs and look pretty good; unfortunately, I harvest a hollow shell full of cabbage root maggots.  Root maggots are at their peak in early June.  That’s why I got interested in dry-gardening giant kohlrabi.

In 1991 we had about 2 surprising inches of rain late in June, so as a test I sowed rutabagas on July 1.  They germinated without more irrigation, but going into the hot summer as small plants with limited root systems and no irrigation at all they became somewhat stunted.  By October 1 the tops were still small and a little gnarly; big roots had not yet formed.  Then the rains came and the rutabagas began growing rapidly.  By November there was a pretty nice crop of medium-size good-eating roots.