Rosemary’s baby has come of age. We call it that because it is one of a few treasured plants that came from Barnsley House not long before Rosemary Verey’s death. It is a tree peony, a seedling that she saved from the shadow of its parents, two venerable and slightly differing plants of the Chinese Paeonia delavayi. For some years, its progress with us was of a kind that used to be only too familiar to British tree peony lovers fits and starts; one step forward, two steps back. This year, however, it has finally decided to perform. Eight blooms nod among its arabesque foliage, combining the colouring of both parents in a mixture of mocha and copper that looks like sunlight through tortoiseshell. Now, all this exceptional seedling lacks is a suitable name. Rosemary’s baby will never do. Mrs Verey herself would have hated it. Doyenne, perhaps?

I am open to suggestions. Evidently, the naming of tree peonies is not to be undertaken lightly. In addition to our Barnsley bounty, we grow several others, Chinese Paeonia suffruticosa cultivars whose epithets are nothing less than poetry. According to Jane Fearnley-Whittingstall’s excellent book Peonies, three of them (Qing Shan Guan Xue, Ge Jin Zi and Yan Long Zi Zhu Pan) translate as ‘the green mountain falls in love with the snow’, ‘beautiful purple scarf’ and ‘coiled dragon in the mist grasping a purple pearl’. These are much more than names. They are miniature word pictures that give us a glimpse of high culture, in some cases as long ago as the Song Dynasty. They do also describe the flowers, capturing their strangely silken tones and their aura, their ancient artistry and dignity.

It is this last quality that made tree peonies China’s imperial flower and which, I suspect, may account for our not seeing more of them. ‘But could I really grow anything as amazing as that?’ is a question I often hear when loitering near the Kelways stand at RHS flower shows. The answer is, yes, very easily. The trick to owning a Ming vase is simply keeping it clean and safe. In recent years, as Rosemary’s baby seems to be telling us, this has become very much easier. ‘Of course,’ says Big Lee, my Chinese lieutenant in major gardening campaigns, ‘your weather now is just like back home dry summer, damp winter, no late frost. Perfect’.

Nevertheless, I am still careful to clear up any fallen leaf litter lest we encourage peony blight. In late autumn, I prune the current season’s shoots down to the next buxom bud from the top. Despite the temptations of plants in flower, autumn is also the best for planting tree peonies. As I do that, I give them side shelter and a soil that is basically John Innes No. 3 with some added grit and garden compost. And I watch, secateurs in hand, for any suckers of Paeonia lactiflora, the herbaceous species onto which they are grafted. But forget all that old fuss about whether they can take sunlight in the morning or rain in the afternoon or milk with their tea. Like the royalty that they are, these plants have been continuously in cultivation since before the Norman Conquest, and will not be fazed by such trifles.

We grow the Chinese varieties in beds, chiefly because their shades of rose madder, mint green and mauve suit the soft planting around them. They are to ferns, the smaller bamboos, hostas and sedges what old-fashioned roses are to herbaceous perennials in a classic mixed border. But not all in a garden should be harmony. Some plants ought to be events, mercifully short lived, but marvellous while they last. For these spectacles, we look further east to the Japanese cultivars of Paeonia suffruticosa, which are generally more clean limbed, floriferous and dazzling. Shocking crimson Taiyo (‘the sun’) and the legendary ‘black’ peony Hatsugarasu (‘the early crow’) are plants for which, as RHS judges used to say, ‘placement can be challenging in the open garden’. Good. I love them all the more for their go to hell looks, and treat them as one-offs grown in large pots on the terrace. There are few plants whose flowering makes me want to drag strangers in from the street. These are two of them.