In early summer I try to visit Oxford. In May and June the city of dreaming spires becomes the city of hanging gardens. The walls of the colleges are draped in the lilac and white racemes of Wisteria sinensis and its scent fills the rarefied air. It is a visit which transports me in time as well as space as the memories of being in the early summer of my life, my undergraduate years and a year of graduate study, return with such clarity and presence that I almost feel young again. I spent many happy hours walking through the University Parks, the flood meadows of the Isis and Cherwell, and the college gardens, filling my eyes with beauties both built and grown, smelling the flowers whilst I could.

In Christ Church meadow a corner of the old city wall had been bridged by a wisteria escaping from a garden within. We stood beneath it, looking up at the blossom-sky above us, resting our eyes in its gentle shade and breathing it in. We kissed perhaps, before we walked on – certainly, that is how I remember it. Beyond our bower, the bright sun was glaring from the hot gravel which crunched beneath our feet, a shimmer rose over the long grass of the meadow, and the many clocks chimed again.

Wisteria does well in Oxford. It has the time and space to grow to its full glory, covering three or four storeys of the college buildings. In its native China it can reach 30m/100′, twining around a supportive tree. On walls, two thirds of that is more common. The lilac flowers and the golden cotswold stone of the walls are a serendipitous pairing. Wisteria needs care through time too. It flowers on spurs and needs careful pruning in January or February and again in July or August to help these spurs develop and to keep the vine contained within the space available.

I had two wisteria in my care for many years. Sadly, the designer who had planted them considered my beloved Wisteria sinensis vulgar and had selected a white cultivar which verged on grey and which was less fragrant than the species. They were greatly appreciated by the goldfinches though, and four or five pairs would nest in each one every year. I would leave the summer pruning as late as I dared, hoping that the last chicks would have fledged and only the empty, delicate mossy cups of the nest would be at risk from the head of my ladder.

I have known thirty year-old wisteria die suddenly from graft failure, which is when the rootstock rejects the scion. It is better to grow a new plant from a cutting and be patient. It will flower in four or five years, but what is that in the life of a plant which endures through centuries. The oldest wisteria in England was planted in 1816 at Fuller’s brewery in London and it still looks splendid. It became the mother plant for the specimen grown at Kew as theirs had failed to establish.

My favourite wisteria of all is in Oxford. Walk down New College Lane into the canyon between New and The Queen’s College. There is an old, high stone wall topped with an iron turnpike. Many years ago, the adventurous stems of a wisteria wound around and through the metal, rendering the spikes still. The black iron spikes garlanded by the soft blossom of the wisteria has always affected me deeply.