The most important thing I ever learned about potatoes is that they need lots of water. Never mind that their fleshy leaves show little sign of wilt in dry weather. A potato plant stressed by drought will consume itself, drawing moisture from some of the tubers already formed, so that fewer of them swell to a good size by harvest time. Not only that, the plant will be less able to fend off the pests and diseases to which potatoes are prone.

To be sure, rotating your potatoes with other garden crops (so that larvae or disease spores do not lie in wait for next year’s crop) will help forestall problems. So will giving them a fertile, somewhat acidic soil, rich in organic matter.

But the real key is water. In one muddy, mosquito-ridden year in which it rained all summer, we had the most bountiful, perfect potatoes ever, and any Colorado potato beetle that showed up must have crawled clear back to Colorado.

This might seem surprising when you consider that Peru, the potato’s chief country of origin, is a relatively dry place.“If Peru had water,” a Peruvian friend once told me, “another cock would crow.”

And indeed, much of that country is desertlike. But traditionally the Andean heights, where thousands of potato varieties were born, have a long rainy season. Alas, both this botanical richness and the rains that nurtured it are threatened, the former by the rise of global agriculture and the latter by global warming.

New potatoes pulled from the ground. (istockphoto)

Here’s some good news from the Food and Agriculture Organization of the United Nations. A potato yields more food per unit of water used in growing it than any other major crop, including twice the protein of both wheat and corn, and four times the calcium of rice. So despite its water needs, the potato is a relatively sustainable crop. Clearly, when the conquistador Pizarro sailed to Peru in 1531, he was after the wrong kind of buried gold.

The fact that you could just about survive on potatoes, with some dairy added to your diet for vitamins A and D, is not going to persuade a modern home gardener to plant spuds. Brown and common, gritty with soil, they don’t have the sex appeal of a tomato or a strawberry. But if you should ever have the chance to sneak out a few new potatoes from the edge of a clump, hose them down, steam them and butter them, I guarantee they will change your mind.

So plant a row. There’s still time to get in a crop if your local feed store has any seed potatoes left. (Don’t worry if they have long sprouts on them; they’re fine.) Water the soil deeply, then lay down a mulch of hay or straw. This not only will prevent the tubers from greening up if they should break through the surface of the soil, it will also help the soil to retain moisture. A soaker hose, a line of drip irrigation or a sprinkler is also a good idea to make sure you get at least an inch of water a week on your potatoes — better yet, two. In fact, plant two rows while you’re about it.

Damrosch’s latest book is “The Four Season Farm Gardener’s Cookbook.”

Tip of the week

Last call for sowing winter squash seeds for a harvest in September and October. Classic butternut varieties are highly productive and resistant to the squash vine borer. Red Kuri is a handsome mini hubbard type. Sow seeds in threes, thinning to a single seedling after germination. Space bush types three feet apart, vining varieties at six feet. Fruit set is dependent on bees and other pollinators: Avoid insecticides that may harm them.

— Adrian Higgins