Then he had a brainwave.
What could be better than a compact red telephone booth, one of hundreds that are being sold off by BT as mobile phones have made them increasingly redundant?
“I chose a phone box because it’s quirky, unique and it’s in a great location,” he says.
“The road is pedestrianised and it’s close to the Theatre Royal. I am in the heart of the city and the community is really lovely.”
And his unusual workplace means that he doesn’t have to rely solely on the quality of his hydrangeas, lilies and cacti to attract customers.
The boxes – first designed in 1924 by Sir Giles Gilbert Scott, architect of Liverpool Cathedral and Battersea Power Station and inspired, ironically, by a Sir John Soane mausoleum – were voted one of Britain’s top 10 classic designs in 2006.
“People love it and want to have their pictures taken with it,” says Mercer, 35, who trained at the prestigious Ballet Rambert in London before being forced to stop dancing due to injury.
“The boxes are iconic and people love that they are being used again rather than being left abandoned and covered in graffiti. They are listed buildings and while space is limited you just have to be creative.
“Since I opened I’ve had a lot of business because of major events in the city. I open from 8am to 6pm. The shop still opens despite any rain – not a problem at the moment. I am only concerned if it’s too windy.”
He is not alone in his decision to operate his business out of a phone box.
It is a growing trend among entrepreneurs.
“It’s all about coming up with genius ideas with limited space,” says Mercer.
One drawback, however, is that because of the lack of security, he is unable to leave his stock at work.
“I have a van and take the plants home when I close up.
The private enterprise charged with selling many of the redundant phone boxes nationwide is the Brighton-based Red Kiosk Company.
“They’re part of this country’s heritage,” says cofounder Eddie Ottewell.
“It’s important we find another use for them instead of them just disappearing.”
And all the signs are that there is widespread demand for the boxes, which cost as little as £3,750 apiece.
Such is the success of Mercer’s business the neighbouring box has been snapped up to launch a takeaway coffee business called the Dialling In Kiosk cafe.
Meanwhile, as his trade continues to grow, Mercer is aiming to start doing deliveries.
He says: “I would say to anyone considering doing something similar ‘Just go for it’.”
