The artist, scythe in hand, slashes at overgrown bamboo in front of a clunky yellow house fit for an Andrew Wyeth painting. This is not a performance piece. This is Alex Katz, 88, arriving in Maine for another summer by Coleman Pond, another summer of work.

He does not spend much time relaxing. Take the recent Sunday that he and his wife, Ada, made their annual migration from SoHo, a seven-hour drive in their BMW Z4. It was raining, but Katz wasn’t about to curl up on the sofa with a cup of chamomile. Before dark, he walked from the yellow house, down a grassy path and into his airy post-and-beam studio. He taped together sections of rolled-out brown paper until a piece stretched seven feet long and tacked it to the wall.

“What are you going to do when it rains?”says Katz, in white tennis hat, T-shirt and blue jeans with a rip in one knee. “I said, ‘Let’s get the studio going.’ ”

This is, in so many ways, the summer of Alex Katz. In Atlanta, an exhibition at the High Museum of Art focuses on his landscapes. In New York, Katz’s familiar figures stretch across the windows of Barney’s department store, and dozens of specially designed products are for sale. And in Waterville, Maine, at the Colby College Museum of Art, the artist’s formative work is featured in an eye-opening retrospective, “Brand New & Terrific: Alex Katz in the 1950s.”

You might think the artist could relax, take out the canoe or sip an Old-Fashioned in an Adirondack chair. But he’s got that brown paper on which he’s sketching out six versions of his daughter-in-law, Vivien. He’s got other work underway, and if you prod just a bit, a complaint or two as well. Katz wonders why no American museum has picked up the High Museum exhibition. It will travel to Spain and Germany instead.

Alex Katz. "Ada," 1959, oil on board, 24 x 24 in. (60.96 x 60.96 cm). (Courtesy Alex Katz)

“It’s the best show I ever made,” he says, before being asked whether, even with all these successes, he’s underappreciated.

“I’m not where I think I should be in the world.”

Which is not to say that Katz is a grumbler. As he approaches 90, he is a dynamic conversationalist, gallery hopper, mentor, critic and family man. And he is, as much as anything, a working artist. Every morning, Katz does 300 push-ups, 200 sit-ups and a litany of stretches before heading to his studio. He doesn’t seem to be racing mortality so much as trying to chase his imagination.

“Look, I did this thing with these six figures,” Katz says, motioning to the wall and the multiple sketches of Vivien, “and I want to see what it looks like. I’m working more now than I ever did in my life and I can’t think of anything more interesting to do than come home and work on this thing which I don’t know what it will end up doing.”

As he speaks, sun floods into the studio, which he had built in the 1980s. It is immaculate and smells of moist wood. The Katz summer home, in contrast, has low ceilings and some of the same features it had when he and his first wife, Jean Cohen, purchased it in 1954. That marriage didn’t last, but his union with Ada, the subject of more than 250 of his works, began when they met in 1957. They were married in 1958, the same year she first came to Maine.

“The light in here is really great,” he says, “and it’s great to be around the trees. When I’m painting, I’m outdoors.”

The area itself is also a spiritual fit. Make no mistake about it. Katz is as New York as a Coney Island hot dog, the son of Russian immigrants who grew up in Queens. But this section of Maine is his perfect summer home. The couple are a short drive from ritzier Camden, with its picturesque storefronts and influx of wealthy vacationers. They can easily go into town for dinner or a cup of coffee. They can also stay here and slip into the background.

Alex Katz. "Irving and Lucy," 1958, oil on canvas, 60 x 60 in. (152.4 x 152.4 cm). (Courtesy Irving and Lucy Sandler)

“I ran into a plumber I hadn’t seen for 20 years and the plumber says to me, ‘Alex, you still painting?’ ” he laughs. “And I said, ‘I try to keep my hand in it.’ ”

Katz is most famous for his portraits. They are color-splashed canvases of garden-party scenes and beach outings and freeze-framed men and women, sad-eyed or mysterious or half-smiling, crowding out blank space. The images are so bold, so alive and so deceivingly simple, you half expect a thought bubble to pop up with a zinger from Elaine May. That’s the Katz who gets lumped in with pop artists. Then there is the other artist. The one who paints trees, houses, buildings, flowers and tables. The Museum of Modern Art in New York holds one of his most beautifully subtle works, “Winter Scene,” a grayish field of bare trees.

“He’s been misunderstood from the beginning,” says Michael Rooks, the curator of Katz’s show at the High Museum, “This Is Now.” “He was never a pop artist. He was a realist going against the grain and provoking his peers into making figurative paintings and doing it unapologetically.”

Is this why Katz’s works sell for so much less than those of many of his peers? Jasper Johns’s and James Rosenquist’s go for millions, as do works by younger painters such as Peter Doig. Last year, the Art Market Monitor analyzed auction sales data for an article titled “The Mystery of Alex Katz’s Market,” wondering why his works sell for, on average, $100,000.

Katz thinks buyers may not accept his landscape work as readily as they do his portraits. He also wonders whether his blunt manner — he just can’t offer faint praise when he doesn’t appreciate another artist’s work — may have held him back. Still, as his artist friend David Salle offers, perhaps there is another answer. None of the above.

“One must always remember, there is no correlation between quality, importance and the art market,” says Salle. “The art market might think there is, but it really makes very little sense.”

The Colby show, which runs through October, follows the work done during a formative decade. Katz was wide open, playing with color, space and subject matter, and about as unfashionable as an artist could be. Realists wondered why he wouldn’t finish the canvas. Moderns thought him old-fashioned. Just consider a short article in Art International from 1960. In calling Katz a figure painter, the piece describes that as “the most boring of all types of painting.”

That didn’t stop Katz. After studying at Cooper Union in New York, he came to Maine to study at the Skowhegan School of Painting and Sculpture. In the ’50s, even as he got to know such luminaries as Johns, Willem de Kooning, Robert Rauschenberg and Andy Warhol, Katz explored his own style. Milton Avery meets Cezanne, reviewer after reviewer wrote. In other words, in a universe of abstract expressionists, work perceived as out of sync.

“When my wife met me,” says Katz, “she said, ‘I thought every intelligent painter would be painting abstracts. What are you doing painting figuratives?’ I was trying to make something that was new and realistic. I didn’t know if it was possible, but I kept searching.”

“It’s one of the sterling examples of someone going their own way and knowing in their heart and mind that it’s the right way and will be perceived that in time,” says Salle.

Diana Tuite, the Colby curator who prepared the exhibition, researched and read the pans from the 1950s.

“Working on this show, I’ve come to realize how incredibly difficult it would have been for someone as young as he was to stake his ground and not budge,” she says.

The Colby show features much of that work, including Katz’s cutouts — figures painted on wood — and a surreal double portrait of Rauschenberg. Many of the paintings are likely to surprise those more familiar with his portraits: The smoldering orange of “Ives Field (1956),” the bright, Impressionistic dashes of “Goldenrod (1955)” and “Flowers (1953).” Then there is the question of how many works are not here.

Katz talks of having destroyed thousands of canvases from that time. But much does survive. Tuite sifted through Katz’s storage area in New York, secured loans from museums and tracked down works in private homes, some of which are rarely, if ever, seen in public.

Colby, about an hour’s drive from Lincolnville, was a natural for the exhibit. In 1992, Katz donated hundreds of his works to the college museum and, four years later, a wing devoted to his work opened. Here, you can also see how Katz supports other artists. His nonprofit foundation, run by his son, Vincent, has placed 385 pieces in museums, ranging from big names such as Chuck Close and David Smith to younger artists.

What’s notable is that Katz, in choosing works, doesn’t adhere to a specific style. Take Ann Pibal, whose colorful abstracts are defined by lines, shapes and patterns on aluminum panels. She has work, given by the foundation, hanging at Colby.

“His understanding of art is so inclusive and sophisticated, so the range of works he has collected don’t necessarily support a particular thesis or vantage point,” says Pibal, 46. “He’s supporting good painting.”

In the barn connected to the yellow house, Katz rubs a kerosene-and-oil-soaked rag on his scythe. That keeps it from rusting. He hangs it up and takes the short walk over to the studio.

Katz does not fake it. If he loves an artist, musician or writer – say Matisse, Rosenquist, Stan Getz, Eve Hesse or Edwin Denby – superlatives flow.

If he’s not moved, he doesn’t offer false praise. Ask him about Mark Bradford, for example, perhaps the most talked-about contemporary artist in recent years, and he shrugs.

“It’s competent, very nice decorative painting, but it just doesn’t interest me.”

There is one artist Katz seems particularly comfortable critiquing. That would be himself.

He sifts through the Colby catalogue and offers judgments, quick takes with little regard for the artist’s feelings.

Of a self-portrait from 1953: “I didn’t care for this much. But other people like it. I don’t know. I thought it was okay. A little decorative.”

Of a woman with a cat: “This one I was never crazy about. Why, I don’t know.”

But there are gems.

The winter scene from MOMA is “the best picture of the time” and a 1959 portrait of abstract expressionist Norman Bluhm is “a perfect picture.”

Vincent Katz, his son, says his father’s unflinching take, his unwillingness to embrace his own success, is what drives him.

“That honestly drives all successful people and all successful artists,” he says. “He says he still wants a show at MOMA. We turn around and say, ‘You’ve had amazing things at this museum or that museum. Look what’s happening right now.’ But it does bother him. I’m always saying, ‘Why don’t you take some time to smell the roses?’ He’s smelling the coffee instead. He wants to get out there and start hitting again.”