Julia Roberts - Pretty woman shows her ugly side but still comes up smiling

In Julia Roberts' new film, Mirror Mirror, a modern-day retelling of the unsuitably old-fashioned story of Snow White, her evil queen character tries everything imaginable to stave off ageing: bird droppings, maggots, garra rufa fish, you name it. In real life, Roberts, now 44, endorses a simpler solution to staving off wrinkles: "Happiness and the love of a good man," she announces, leaning forward from a squishy Santa Monica hotel sofa to knock on the table. "My husband thinks I'm pretty, that feels good. My mum is still beautiful. I have all my teeth. So far so good. But really, one shouldn't linger too long in front of the mirror."

Roberts still looks like her very pretty woman self; long chestnut curls, face pliable, not very lined for her age but not suspiciously unlined either. She also credits "a lot of Lancôme" but no obsession with off-the-wall treatments. Kombucha mushroom tea has recently re-reared its head as a "magical" potion in Hollywood, alongside the even more unsavoury likes of cow placenta. "Cow placenta?" she repeats, incredulously. "Can you imagine going into Whole Foods, and saying, 'Do you have any cow placenta?'" And she throws her head back and laughs that iconic Julia Roberts laugh. "I love that the queen is so blatantly psychotically possessed by this idea in a time where people can really be so out of sync with what is truly beautiful about them."

These days, Roberts insists her life isn't all about Hollywood either. "I feel I have another profession other than acting. Acting has kind of become my favourite hobby, I'm a great domestic artist now." She and second husband, cameraman Danny Moder will celebrate 10 years of marriage in July. But they are spending an awful lot of time living at their more career-friendly Malibu oceanfront spread rather than their New Mexico home, and Roberts' slate is chock-a-block with both starring vehicles and projects she is producing. Given that she wore a different crown this time last year (the poorly received Larry Crowne opposite old pal Tom Hanks), Roberts' career is fundamentally rosy, buoyed by some smart choices. She's about to start a long-overdue Hollywood production of Larry Kramer's acclaimed play about the incipient days of Aids, The Normal Heart, and after that will play Meryl Streep's daughter in another stage-to-screen adaptation, Tracy Letts' Pulitzer Prize-winning play, August: Osage County. Jesus Henry Christ starring Toni Collette and Michael Sheen, which she produced, is released in the US next month. As a producer, she has another seven projects in development, and is scheduled to star in none of them.

If Mirror Mirror appears a calculated casting-against-type effort on her part, it was not intended as such. Roberts simply confesses to a professional crush on Tarsem Singh, famous as the Hollywood visionary behind artistically sculpted outings like Immortals and The Fall rather than funny, at times quite facetious "family" outings like Mirror Mirror. He saw no one else but Roberts in the role. She saw no artistic appeal especially in playing evil. "To me, everything has its challenges – being funny, being nice, being mean. It's all the same on the day. You are trying to do it the best that you can because it's going to last forever."

Her children, twins Hazel and Phinnaeus, seven and Henry, four, haven't seen the film. She says they will "eventually. They are a little young for that still, but I think there will be a day where they probably will think it's quite amusing." Viewing of any description isn't particularly big in the Roberts household, but book reading is, fairy tales included, with gory bits excised. "Look at Rapunzel. That story is so savage. The prince falls out of the tower, and his eyes get gouged out. I read that story to my kids one night and well, very quickly it becomes The End and, 'That was a short one!' We call it parental editing."

As unthreatening as Roberts is in person, today clad in an all-white J Brand trouser suit, it's easy to imagine a young actress like Lily Collins, 23, being overawed to have her as "stepmum". "I just gave her a huge hug when we met," says Roberts, "and that was done with." Or not. "She was so amazing to everyone," reports Collins, clearly still overawed. "No matter if you were in craft service or a grip or Armie or myself, she treated everyone just the same. It was all about being part of this team. The other thing that struck me was that even at work, she's a mum first. Her kids are so well behaved and sweet and that's all a testament to Julia and Danny."

So what does bring out the "evil" in Roberts? "People who are late and people who are stupid. That's a terrible thing to say, I know. And if you show up late with a really stupid excuse." And her own imperfections? "I'm sure I have hundreds, but to advertise them would really kind of put me in a bad position. What I will say is I'm never late."

Perhaps because she's never home faffing about on Facebook (inspiration for a clever clever Mirror Mirror ad campaign). "I've never seen Facebook," she says, a smidgeon of pride in her tone, "but I did see The Social Network. I've never had Twitter. I email and text but that's it."

Roberts recently noted that for up-and-coming stars there is "the express elevator and there's rehab". I ask if her perception of Hollywood is a negative one. "I don't think that at all actually. I'm not a negative person in any way, and I certainly wouldn't participate in an industry that I felt was inherently negative. I just think the way that the business works now and how movies are made and how people are cast, it's just a very different thing than 25 years ago. I have a very distant point of view of that experience now compared to the experience that I had."

Things one might imagine would keep Roberts up at night – the oft-perceived image of the business as dog eat dog and feverishly competitive, for example – do not concern her at all. "I'm so not competitive, I never have been really. I think that there's a place and part for everybody. I have never felt that aggression towards anybody younger, or anybody my age doing something else. It's just not part of my DNA I don't think. I believe that the parts that we play are part of the sort of destiny of ourselves as actors."

But her life is not all about waiting for the right things to arrive at the right time. The aspects of it which she can demonstrably control are the most important: How she raises her children and the examples she sets for them. "We very much try to limit our impact. A family of five can produce a lot of waste, so we compost and have chickens, so that takes care of most of our food waste. We don't use any superfluous paper products in our house, no paper towels or Ziploc bags for lunches. In fact, our school has a waste-free lunch policy. We have solar shingles on our roof, I drive a bio-diesel and a Prius." She even grows her own vegetables. "We have a lettuce garden because I don't like to buy lettuce in a plastic box. That just makes me have a pain in my stomach." They also grow kale and carrots currently, and buy everything else from a local farmers' co-op.

Most surprising in this all-encompassing media age is the fact that Roberts and her family are so rarely photographed. Many A-list celebrities' children's faces are familiar to us, not so with Roberts' brood though she denies taking extraordinary measures to this end. "There are places I don't go, but I also will not alter the shape of my life. I think you live the life that you want to, that you've cultivated. If you take care of it, hopefully it just spreads out before you. Plus I don't get that kind of frenzied energy from people, I never really have. I think that's just an energetic destiny we all have with each other. People might say hi, but children are friendly, so they don't find friendliness suspicious."

Roberts seems so fearless in every aspect of her life. Is there anything that gives her pause: The prospect of "being" Meryl Streep's daughter perhaps? "Yes, you just made me feel a little nauseous. I worship her so yeah, I'm on pins and needles for sure."

And were she to cast a cinematic spell to lure her own acting Prince Charming? Her answer is, like the woman herself, surprising, and quite contrary to what one might imagine. "Anthony Hopkins springs to mind. But my husband knows that."

There's another great gale of laughter and she practically leaps off the sofa. She gives me sort of a half-hug, putting her arm round my back while apologising that she has to "run and say goodbye to my children. But thank you. That was the best conversation I've had all day."

'Mirror Mirror' opens on 2 April