An eye for an iris

This first weekend after English midsummer is heavenly. As the light fades I enjoy that pale pink old rose, Fantin Latour, and this year, its delayed companion, the excellent hardy geranium Blue Cloud, whose pale blue flowers float in the half-light. From 7pm onwards the colours loom more clearly through fading light. Most of them are consequences of decisions taken years ago and patiently left to mature.

Whenever possible, sit still and do not move gardens. If you know you will move, grow long-term winners in big pots so that you can take them with you. I hope that one day they find a permanent home.

In the previous spell of glaring heat the winners were quite different. We have just come out of a superb season for irises. They have never been better. My pleasure from them began in late April with a dark-flowered little beauty called Devil Baby, so deep a shade of red that it looks almost black: it flowers at a height of about nine inches.

These little irises are frowned on by alpine purists, but they are bright and cheering in beds of mountain flowers. They also look lovely in gaps in paving in an urban front garden. Excellent new varieties continue to proliferate, some of which are as intensely coloured as those iconic alpine spring flowers, mountain gentians.

The season continued with May’s thin-leaved sibirica irises, great favourites of mine, especially in selected varieties, all easy to grow. Yearly, I marvel in May and early June at the excellent sibirica Silver Edge, whose flowers of dark violet are thinly edged with glistening white.

Sibirica irises grow well in half-shade, making them excellent choices for most back gardens in London. They do not need damp ground, though they flourish in it.

The best irises for damp sites are the kaempferi irises from Japan. There is a superb display of them in the fine gardens around PepsiCo’s world headquarters at Purchase in New York State. The irises were added as a pendant to the park’s fine landscaping, which had been done by the maestro, Russell Page.

As a linking feature, he laid a remarkable golden pathway, now well restored, which winds curvily through the green acres of the grounds. If he had lived to see mature Japanese irises in long beds beyond it he would have been delighted. In acid soil, beside a lake or pond, Japanese kaempferi irises are wonderfully beautiful.

Elsewhere, irises mean big bearded ones, bred in ever-greater yearly numbers. They are dazzlingly beautiful and their flowers are good survivors on a hot day. They love a dry, sunny site, exemplified by their annual display in Italy on a hillside beside the Piazzale Michelangelo overlooking Florence.

There, bearded irises are judged and ranked in beds banked up with the local soil. They are a fabulous sight in late April, loving the hot conditions in which most of them flower so well.

I realise I am under-irised. For years I have been staring this obvious option in the face, wrongly believing that irises’ display would be too brief and that there must be other lovely flowers for dry soil that will last for many more weeks. I have found some alternatives, but not many. Meanwhile bearded irises have continued to improve. At recent Chelsea Flower Shows I woke up to the truth.

Chelsea’s most impressive recent exhibits of irises have come from France. The family of Cayeux are famous iris breeders there, headed by Richard who is the fourth in the line, his daughter preparing to be the fifth. When he first showed his richly coloured, heavily flowered irises, British exhibitors wondered if they would fare so well in cloudier British conditions.

That worry need not be yours, for three reasons. Many of you garden abroad in sunny climates anyway, where these Cayeux irises are excellent. Summers, meanwhile, continue to be hotter in Britain itself. The Cayeux family have explained to me on their show stands at Chelsea the many varieties that would become happy British residents.

Advised by them, I tried their amazing iris Mer du Sud. Its big flowers are a deep ocean blue and appear with gratifying freedom. It has been the top sight in my garden for the first three weeks in June, glowing in the hot sun and adding an unprecedented depth of colour.

The flower stems are firm and thick and do not need staking. The flowers are big and ruffled and go on opening from back-up buds beside the main one of the moment. Within two years Mer du Sud has made such a mat of rhizomes that I can split it in about three weeks’ time and have another dozen plants next year.

Previously, one of my favourites had been a 1930s bearded American iris called Wabash. Jolted into action by its new neighbour, it too has flowered freely this year, showing its fine combination of violet-purple, a white edging, a yellow beard and grey-white upright petals at its centre, the ones known as standards. It is still good but not nearly as good as Mer du Sud.

Irises like to be transplanted in July or early August, giving their rhizomes time to build up before winter

I recommend the Cayeux website with pictures and a video tour of the iris fields, otherwise past their best now for visitors (iris-cayeux.com). I also recommend buying the Cayeux catalogue as a dreamy weekend read, as it is a well-illustrated mine of wonderful varieties and sound advice on growing them.

I endorse the advice to feed the plants with a dusting of good old bone meal next month, four weeks after flowering, and next year, to give another such dusting in early April. I also endorse the firm advice not to use high nitrogen-based fertilisers on irises, Miracle Gro and so forth. They can cause the rhizomes to rot.

At the British Iris Society website you will find a helpful list of other good suppliers (britishirissociety.org.uk). Kelways of Langport is one option in the UK and Sue Marshall’s Iris of Sissinghurst another. Most of these UK growers now stock the best of Cayeux’s own hybrids, but I prefer to buy from the originators, a process not blocked by Brexit: delivery charges from £11.50 upwards apply to the UK, not much higher than those of many nurseries already in Britain.

Try among the newest hybrids the Rajasthan with golden-yellow flowers deepening to caramel and a scent that Cayeux even compares to frangipani. My young plant has indeed produced a stem with 10 buds, just as they promise.

Among whites, Got Milk, bred in 2002, is very free growing, as is the deep violet-blue Rosalie Figge. Cayeux’s own Domino Noir took second prize in the Chelsea competition for plant of the year in 2014. It is a superb blend of dark falls and blue-edged lavender white standards.

Here is the good news. Now is just the time to order and act on this new adventure. Irises like to be transplanted in July or early August, giving their rhizomes time to build up before winter. Other showpieces of the midsummer English garden are best ordered and planted only from mid to late autumn. Up your iris standards and you too will be amazed at the results.

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