Charles Quest-Ritson tells the story of a mysterious but ravishingly beautiful rose he first came across in the Czech Republic.

Rose - R. x francofortuna

When my daughter Camilla was posted to Prague – she’s a diplomat – she lived in a suburb called Barrandov, famous in its day as the home of the Czech film industry. We all went there for Christmas one year and I noticed that part of her garden was carpeted – I could almost say ‘invaded’ – by a small, creeping rose.

The leaves were an unusual shape, being slightly corrugated like a hornbeam’s, but I had no idea what it might be, so I dug up some pieces and planted them back in England. They grew prodigiously to about 6ft in height and turned out to be something rather rare: a ‘Frankfurt’ rose.

Frankfurt roses are a small group of closely allied hybrids between the super-hardy May-flowering species Rosa majalis and the fat-cabbage Centifolia roses, much loved by Dutch flower painters. Almost all are extinct now, but their existence is recorded in a number of 18th-century florilegia such as Salomon Pinhas’s prints of the roses growing at Wilhelmshöhe in Kassel in the early 1800s.

Goethe used them as short climbing roses to cover the garden house where he worked in the Park an der Ilm in Weimar. I’ve seen them occasionally in old rose collections, but their individual names seem to have been forgotten, so they tend to bear vague and unhelpful labels.

“I like the thought that the rose is so old as to be nameless”

The best-known of the Frankfurt roses (called R. x francofurtana by botanists, but no one remembers why) is Empress Josephine. Snobs call it Impératrice Joséphine, but both are bogus names because it was introduced in about 1950 by Graham Stuart Thomas. He had received it from a Yorkshire plantsman called Bobbie James, who thought it resembled a rose called Turbin-ata that Redouté had painted.

The link to Napoleon’s delicious wife was too good to lose, which means that what we still grow as Empress Josephine is another of those old roses in search of a correct name.

I have no idea what name the rose we brought from Prague should carry. So little research has been done on Frankfurt roses that there is no chance of identifying it correctly, but it would make a good PhD project for an aspiring horticulturist – bringing together propagation material of all the plants that seem to be Francofurtanas, using DNA analysis to group and sepa-rate them, and comparing the plants with old paintings.

My ‘Francofurtana ex Prague’ (as we call it) is typical of the group. It has large pink flowers, very double, but scentless. The petals are very thin (this trait comes from R. majalis) and the flowers tend to ‘ball’ in wet weather. Truth to tell, we get a decent flower off it only once every three or four years. Why bother to keep it? Well, I like the connection with Camilla’s house in Barrandov and I like the thought that the rose is so old as to be nameless.

When we moved house, I forgot to pot up a piece for our new garden, so I asked Michael Marriott, the ever-helpful public face of David Austin Roses, if his firm could propagate it for me. Only one plant ‘took’ and was ready for me 18 months later.

The plant I brought from Prague was lost completely (we sold the house for development) so Michael’s remained the only specimen in cultivation. I panicked when I realised this, because budding had proved difficult and then I remembered the old technique of ‘mounding up’ a shrub as a way of producing new plants.

You cut it almost down to ground level, preferably in winter, and pour a mass of garden soil on top of it (I use spent compost from plants that have died in their pots and last year’s tomato growbags).

The new shoots that come up from below the surface put on roots as they grow and, a year later, you can push away the dumped soil, cut the new stems off below the roots and, lo and behold, you have several new plants. What’s more, they are on their own roots and will grow into a thicket that will always be with you.

My plants of Francofurtana are now expanding at the rate of about 3ft a year. I reckon they will have reached the M25 by 8517. Perhaps, by then, someone will know its proper name.

Charles Quest-Ritson wrote the RHS Encyclopedia of Roses