Best in show: The RHS is seeking the 'plant of the centenary' to mark 100 years Chelsea

There's a space in my garden. Finally, a space. A space that could be filled with something new. Or possibly something old, as it turns out, because I am perusing the David Austin roses at my local garden centre, where they have a particularly good selection, and the ones I hanker to put in my trolley are soppy traditional roses such as "Albéric Barbier" and "Madame Isaac Pereire".

Both varieties made their appearance on the global stage well before the First World War, in the bygone days that were already mere memory by the time Proust went and dipped his biscuit into a lime-blossom tisane, and both roses possess fabulous perfume and a distinct old-world glamour.

There are plenty of other roses that make my heart beat a little quicker in a slightly 19th-century way. If you want genuinely Proustian, what about "Albertine", who made Marcel her love slave? Yet David Austin, the great rose breeder himself, seems determined to sway me from my path. Because Austin spends most of his waking hours trying to devise new roses that spectacularly outdo all the charms of Albéric and Madame P – the recently gorgeous "Benjamin Britten", the light-on-her-feet "Darcey Bussell" and the oh-so-terribly-2011 "William and Catherine", to name just a few examples.

Plus, any minute now, he'll be blowing his trumpet to herald some more new arrivals, because for David Austin and all other plant breeders, the Chelsea Flower Show, which opens to the public on 21 May, is the horticultural industry's best platform for launching new plants.

Never mind the show gardens: Chelsea's new-plant introductions are a massive attraction for gardening enthusiasts, and journalists arriving for press day at dawn are consequently handed a three-page stapled bumpf listing all the launch times, along with the new arrivals' associated celebrity. (Well, it is Chelsea, after all.) Which can lead to a profusion of confusion, frankly. So maybe we'll be glad to hear that this year, in celebration of 100 years of the show since its 1913 debut, the RHS is trying to establish exactly which of the plants launched at Chelsea over the past century actually qualifies for the title "Plant of the Centenary".

Actually, they're making it a sort of competition. Top horticulturalists such as Roy Lancaster and Carol Klein helped to nominate the 10-plant shortlist, but the public is being asked to vote on the final winner. So we sit and toss up the merits of the Russell Hybrid Lupins, glorious blazes of colour first shown in 1939, or argue for the noughties favourite, Geranium "Rozanne", a bright, rewarding blue that flowers all summer long, smothers out weeds and requires little attention.

My vote, though, will probably go to 1958's sweetheart Rosa "Iceberg", the sleekest and coolest of the white roses, always exuding a film-star magnetism. Which just goes to show that often new things don't seduce me as much as the old. (And I spend a few minutes at the garden centre, pondering whether "Iceberg" would have the same steely appeal for me were it called "Delia Smith" or similar.)

The new is always tempting, and I'll be perusing the Great Pavilion at Chelsea and all the latest introductions with as much pleasure as ever. But in the end it's the positively medieval "Rosa Mundi" that's made it into my garden's waiting space. "Bred prior to the 16th century", is all it says on the label. Which is quite enough pedigree for me.

Vote online for your Plant of the Centenary at rhs.org.uk/chelsea/potc

Four more to be launched at Chelsea this year

'Chelsea'

This appropriately named bloom is a pure white, with rather rounded petals, giving a lovely old-fashioned feel. From raymondevisonclematis.com

'The Lady Gardener'

A perfect apricot with plenty of petals, accompanied by a good tea fragrance. From davidaustinroses.com

'Sichuan Silk'

Meconopsis, the Himalayan poppy, normally comes in sky-blue; this one is an Imperial Chinese red. From harperley hallfarmnurseries.co.uk

'Barbe Noir'

A happily piratical bearded iris flying white flags above and showing its true black colours below. From iris-cayeux.com