People bought so many kale seeds this spring that at least one company ran out of them. According to Julius Koenig, a product technician at Johnny’s Selected Seeds, kale sales rose 20 to 30 percent this year, an unexpected spike, and all the company’s hybrid kales (except the ornamental ones) are sold out completely. Adds fellow technician Lindsay Spigel, “My mom will eat it now. That means it has really become mainstream.”

Have I been blind or did this happen overnight? Was it all those little round green bumper stickers that read “Eat More Kale?”

I quizzed Daniel Nagengast, owner of Seeds From Italy, about the whys and wherefores of the kale surge. “It seems like every order out of here includes a packet of Cavolo Nero [one of the popular Tuscan varieties],” he said. “Because of the leafy-greens-and-calcium connection, people grasp that it is very good for you. Kale is a gateway for a more greens-intensive lifestyle.” Jo-Anne Ohms, owner ofJohn Scheepers Kitchen Garden Seeds, reports: “It seems like every client is ordering kale.”

So it’s good for you — a superfood, even. And some varieties are more mild-tasting than the tougher curly kales that were once the only kind available. Smooth kales, such as the deep blue-green Tuscan and the magenta-stemmed Red Russian types, lend themselves to raw salads, teamed up with hearty additions such as bacon, garlic, chopped hard-boiled eggs and Parmesan cheese. And am I the last to hear about massaging kale first, as you would a Kobe steer? This tenderizes the leaves without cooking, explains my friend Alexandra, who rubs hers with coarse salt. Others use oil and vinegar, so that the traditional light salad toss becomes a more athletic knead-and-pummel.

Lance Frazon, general manager of Scheepers, tells me that kale now goes into smoothies and power shakes as well.

Removing ribs from Tuscan kale makes it suitable for chips. (Barbara Damrosch /Barbara Damrosch )

But if kale has become the new spinach, its most frequently mentioned repurposing is the kale chip, an item I first encountered some years back as “crispy kale” at theBurning Tree Restaurant in Otter Creek, Maine. To make kale chips, you start with de-ribbed kale with the leaves torn in pieces. Then all you do is squirt olive oil on a cookie sheet, spread the kale in a single layer and bake until crisp. I set the oven at 275 degrees, and it’s done in about 15 minutes. The low temperature lets them crisp without browning. Salting them at the end rather than the beginning keeps them from steaming and becoming soggy.

Employing fat, salt and crispness is a well-proven food alchemy, and a kale chip is simply a more healthful stand-in for a potato chip — and just as satisfying. Set a plate of them out for snacking and they will soon disappear. They have evolved to include very filling versions in which they are dredged in cheese, tahini or even peanuts, not to mention the gamut of seasonings from chipotle to curry. But I like them best when they taste of kale.

The dawning of the age of arugula seemed to focus on the dainty and the petite. The age of kale seems more about robust food that even a real man can eat. I approached a hunting enthusiast about the idea of a kale side dish along with his favorite meal of grilled moose. “I like it best raw in a salad,” he said.

Tip of the week:

Container-grown tomato plants should be of the determinate type, which are more compact than garden vining tomatoes. Place a cage or stake in the pot when the tomato is still young to avoid later damage. Popular and high-performing varieties include Patio Princess, La Roma, Red Robin and Bush Early Girl. Buy small transplants, which will establish better than larger ones already in flower. — Adrian Higgins

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