It’s one of the most enjoyable, easygoing things you can do on a sunny Sunday in Dublin: stroll around Merrion Square, look at the paintings and chat to the artists. The outdoor art gallery on the square has been going for 30 years, and on September 13th a street party will mark the anniversary of its opening, complete with music, family activities and a pop-up gallery.

"There's a very jolly atmosphere on Merrion Square at the moment," says Elizabeth Prendergast, who has been showing her botanical flower paintings on the square for nearly a decade.

Earlier this year she helped to form the Merrion Square Artists' Association, which works with Dublin City Council to promote the gallery. "We're the survivors," she says. "Quite a few people have survived the recession, and the idea is to get us noticed again."

Debbie Chapman has been showing on Merrion Square for 11 years. She went to Australia for a while, but when she returned to Ireland, she couldn't wait to get back on the square. "I craved the feedback that you get from the public when you're there," she says. "And it's a huge opportunity to share ideas with other artists. Somebody will always be able to help you along; there's always a pat on the back whenever you bring new work."

And, of course, it’s a business. It costs €240 a year to buy a licence from Dublin City Council. Artists also have to purchase public-liability insurance and show a tax-compliance certificate. Effectively, this means the gallery is curated by the public, Chapman says. “If the artists aren’t good enough, they won’t have the buyers and they won’t stay. You’re not going to sit out in all weathers if your work is not selling.”

At the moment, almost 200 artists sell on the square, ranging from young people just out of college to full-time professionals. Although she’s there every Sunday, Chapman says the range of styles and forms on the railings never ceases to amaze her.

“There’s work I love on the square. There’s work I hate on the square. But if nobody liked it, then those people wouldn’t be there,” she says.

She describes her current body of work as “urban landscapes with a figurative element . . . I live in the city. It’s my environment. It’s what I see, and what I love,” she says.

For Willie Redmond, who has been showing on the square for 15 years, the openness and informality of the space is perhaps its biggest draw.

“There’s room for everybody,” he says. “People aren’t intimidated, walking round the square. You’re meeting the artist and you’re also getting the story behind the picture – and the story behind the technique, which breaks down a lot of barriers too.”

Redmond, who was born in Edenderry, Co Offaly, currently shows paintings of street scenes and populated areas. He also brings some of his more experimental work before it goes on display at art centres or galleries. He has pretty much seen it all in his time on the square. During the Celtic Tiger years, it was hopping. During the downturn, people wouldn't even take business cards from the artists, let alone buy anything.

But Redmond says maintaining a presence on Merrion Square is always worthwhile. “It’s tough at times. But you’re doing your homework. It might not pay off straight away, but you’re sowing seeds for people. They’ve seen the style, they have an idea and they come back a few months later when they are ready to buy the piece.

“It’s a long-term exercise. I always say to younger artists who arrive in the Irish arts scene: it’s not a five-year get-rich plan. It’s a 20-year plan. It’s a slow burner.”

When Elizabeth Prendergast put her name down for a spot on the square there was a seven-year waiting list.

“Suddenly it came through and I was going, ‘What will I paint?’ ” She put up some paintings of flowers, and they were an immediate hit. Now, she says, she has sold paintings to people from all over the world as well as closer to home.

“I keep saying I’ll do this until I get bored of painting flowers. And every year I’m just dying for the snowdrops to come up,” she says.

“It’s a big sacrifice, giving up your Sundays, winter and summer. But I tell myself, ‘These paintings will not sell in my own sittingroom.’ ”

The 30th birthday celebration is designed to be a bit of fun both for artists and for the public, she says. "We'll do a painting demonstration, and one of the artists, Simon Meyler, is bringing his band along."

The star of the pop-up gallery, appropriately, will the square itself, in the form of 50 miniature “Merrion Squares”, about a foot square, painted by the artists and on sale at €50 each. Proceeds will go to the association, and to the Capuchin Day Centre for homeless people.

merrionart.com