Spanish born professional gardener Medina won the 12-month vocational scholarship in garden design, sponsored by Bradstone. It will see her build a garden at the Chelsea Flower Show 2010.
Beardshaw said: "I see many students through my teaching and the thing that excites me is when you find someone with a mischievous sparkle in their eye. What we spotted in Maria is that as a child she dreamt of being a landscape architect.
"She has proved she has the passion and the dedication and she has that real sparkle of somebody who is going to make us all smile and that's what swung it for all of us - it was a unanimous decision."
Medina's garden - Water Pirouetting for a Colourful Audience - was inspired by a circus theme and was awarded a bronze medal at the show.
The scholarship was judged by a panel including Beardshaw, the wife of Bradstone chief Biddy Bolsover and RHS council member Richard Webb.
Medina said: "I'm delighted. I think it's going to be a very big step for my career. I have always wanted to get into garden design. I do maintenance and some planting schemes but design is the focus for me from now on and it's something I have always wanted."
She added: "My style is going to be modern with a touch of softness on plants and colours. I like to use straight lines and to use new with old. In Chelsea I would like to take the art of Granada and adapt it for England."
The garden included plants grown by Medina herself, together with some sourced from Wyevale East and some from St Peters Garden Centre in Worcester.
The scholarship gets underway immediately, with Medina helping 2009 scholar Paul Hervey-Brookes with his Chelsea garden highlighting biodiversity.
Medina's design for next year will be themed around the atom to celebrate UNESCO's International Year of Chemistry.
Beardshaw has just returned from New Zealand, where he picked up a gold medal at the Ellerslie International Flower Show in Christchurch. He will soon begin filming on a new gardening television programme, as yet unnamed.
He added: "I'm involved with a project that starts filming next week where I'm encouraging gardeners to get the best out of their gardens. I will be filming with Colin Donaldson and will be tackling gardens over six months, with frequent visits to get people to make the best decisions."
The programme will be shown on BBC Northern Ireland. Although details are not yet confirmed, a pilot in early summer is expected to be followed by a full series next year, with the possibility of it being picked up by the whole of the UK.