Touring with Bowie was a thrill. But I was on a high for weeks after winning gold at the Chelsea Flower Show

Kim Wilde on her unlikely transformation from multimillion-selling pop icon to green-fingered goddess.

Eighties icon Kim Wilde confesses to being ‘gutted when Madonna came along’. ‘It was awful – the worst time in my life. I just thought, “How am I ever going to compete with thìs?”‘

This year, as Wilde turns 60, she will celebrate her own life in music with a greatest-hits tour and best-of album, taking full ownership of her impressive pop output. But once again, a lifetime later, she finds herself going head to head with her old nemesis. However, as Madonna’s Madame X tour rolls into the UK this month, Wilde is more concerned about Madge’s joints holding up.

‘I read that she had a problem with her knee’, she says. ‘That she’d had to cancel some shows. I felt like phoning her up and telling her to see my knee doctor. He sorted me out. I had a cartilage problem with the meniscus in my knee. So if she needs my guy’s number…’

Kids in America propelled Wilde to fame in 1981. The international anthem was written by her brother Ricky and dad, original British rock ‘n’ roller Marty Wilde, and at one stage was shifting 60,000 copies a day. She had seven more Top 10 singles in the UK but never a No. 1. ‘Although having a No. 1 in America almost made up for it’, she says, referring to her re-working of the Motown classic You Keep Me Hangin’ On, which topped the US Billboard chart in 1986.

She went on to sell more than 30 million records and, with her chilling good looks, break a few hearts. ‘I feel very grateful that I got my mum’s gorgeous nose and my dad’s fabulous mouth’, she says, recollecting that she was bullied at school for ‘having lips like Mick Jagger, like that was a bad thing’.

In retrospect, Wilde looked like Taylor Swift’s big bad sister, with her sulky pout, artful tangle of blonde hair, trademark black tuxedo and blue jeans. ‘I had long legs and they did well with jeans’, she acknowledges. ‘I knew how to wear a pair of jeans, that’s for sure.’

She also knew how to wear a scowl: Wilde seemed to glower her way through the Eighties. ‘Most photographers I was working with were men’, she explains. ‘And they had this pretty old-fashioned notion that the only way a woman should be seen is with a smile on her face. It was always, “Come on, love, give us a smile. Why are you so grumpy?” And that made me even grumpier.’

She agrees that she was probably subjected to a few more sordid requests but brushes such sleaziness aside. ‘There were one or two crusty old guys hanging around with their crusty old ways’, she breezes. ‘But I always had a really great sense of humour, which hasn’t left me, and that got me through the worst of any situation, and still does.’

In 1987 Michael Jackson invited Wilde to joing him on his Bad tour and open 33 shows across Europe including in Cork. She observed a superstar alone in his own universe. ‘He was an elusive character then, and kept himself to himself’, she remembers. ‘We never sat and had a chat. We had a publicity photograph taken together and that was the longest we spent together. I’ve met a lot of very famous people – I grew up with a very famous person in the house, my dad was the Robbie Williams of his day! – so fame doesn’t faze me at all. But Michael Jackson was by far the most enigmatic character I’ve ever encountered. He was in another world, whatever that was.’

Two years after the tour, Wilde’s own world came crashing down the day after her 30th birthday, when it dawned that her time as a pop phenomenon might be over. ‘I felt really lost’, she says, ‘like I was closing in on myself. My inclination was to shut down. Having to deal with the fact that the success I’d had, which was so massive, had dissipated was very confusing.’

Mother Nature saved the day. ‘Within a year, I left London’, she recalls. ‘I moved back up to Hertfordshire. That was really the big turning point. I started noticing the natural world around me and getting involved in gardening and immersing myself in it. Nature brought me back to life.’

Wilde bought and renovated a 16th-century barn with two acres, where she still lives with her husband, actor and writer Hal Fowler and their two children, Harry, 22, and Rose, 19. It was while studying planting and planting design at Capel Manor Horticultural College in 2002 that Wilde was asked to appear on the BBC’s Better Gardens and Garden Invaders and a parallel career as a daughter of the soil blossomed. Her horticultural high point was winning a gold medal at the 2005 Chelsea Flower Show for her Cumbrian fellside garden – a triumph she believes might even trump supporting David Bowie in 1990. ‘I was completely besotted with him’, she sighs. ‘He was so approachable and lovely, it was such a thrill to work with him. But that RHS gold put me on a high for years.’

She remains a devoted student of music. ‘Music has been my greatest, most loyal, most loving companion. And it’s been the same for my dad, which is why he still tours at 80.’ And it’s also why Kim Wilde will see in her 60th birthday on the road, doing what she loves best (‘apart from weeding’). ‘Getting older has been a hugely positive experience’, she says. ‘I’m just going to hurtle towards 60 with as much dash and dare as I can muster.’

Here’s hoping her knees don’t go. ‘Me and Madonna both’, she laughs throatily. ‘We’ve got to look after ourselves, we’re not kids any more.’