Early in the year, when every tiny shift in growth is a relief, the iris start to score their vertical, cutting us boldly off from one season and taking us into the next. In the marshy ground of ditches and in a distinctive line at the margins of ponds and lakes, it is our native flag iris, Iris pseudacorus, that makes this mark. Pushing away from ground that is so cold it is hard to believe it will ever be able to muster growth, its spears need just a glimpse of April sunshine to move, and before long they are already standing a foot proud. Backlit by low sun, the envelopes of foliage are at their best, full of expectation, one layer of leaf folded over the next; dark green where the leaves are overlapping, pale and luminous where only one thick. This is just the beginning.
The iris is a good metaphor for the flood of energy that leads up to Midsummer's Day, and it is no coincidence that the Japanese choose to plant whole gardens with moisture-loving I ensata and I kaempferi for precisely this moment. Although you often see images of these gardens apparently floating in water, part of the event when they flower is that the gardens are flooded to create the reflections, a double dose to mark a zenith in the season. A rush that in Britain will see meadows filling and softening contours, verges hung heavy and hedges fat with fresh extension growth. At no other point in the year are the greens so vibrant, the garden so full with expectation as right here and now, when dawn breaks at four and you can sit out until eleven.
Although most of the iris are past their best by Midsummer's Day, this is no reason not to draw them to attention, for their foliage continues to be wonderful in the garden and their seed pods are just getting going and will be good for months. Although I grow the sun-loving I germanica where there is a hot spot and a need for flamboyance in May, I have no place for them now in my garden as it becomes progressively fuller.
But, if truth were told, I prefer those that like to live on the damp side as these, on the whole, are happier in company and modest enough for even quite small gardens. The aforementioned I pseudacorus is a wonderful thing if you have the room, but this is a plant that can easily overwhelm its neighbours, and I only ever plant it with burly aquatics and on a big scale. It is so strong it even competes with bulrush and outstrips many of its companions where there is livestock, since herbivores choose to ignore its poisonous growth. It is a plant for the larger garden and, all too often, I have seen it sitting fat in a domestic pond, displacing almost everything around it like a big baby in a sink.
Although variegation is rarely restful, one of the best is I pseudacorus 'Variegata', with its flash of cream and green. This colouring is most evident early in the year but, by the time summer kicks in, it fades to green, assuming a more modest air and competing less with its neighbours. Its growth is also moderated slightly by having just that bit less chlorophyll coursing through its veins. Although I don't have sufficient water in my garden - no more than a small copper with a solitary water lily - I do grow a close relative of the Yellow Flag, a cross from American parentage of the equivalent species. In the ground with neither bog nor an endless supply of water, my I x robusta 'Gerald Darby' is a manageable size, no more than hip height when it is in leaf, a little taller when in flower.
As it emerges, the dark staining in the young foliage is what singles this plant out - a deep blue, the blades looking like they have drawn up Quink ink. The colouring travels into the young foliage from the heart of the plant and then up into the flowering stems, as they rise out of the arch of the now heavy leaf. This darkness is insistent and it only stops where the green sheath protects the dark buds. These teeter for a few days as if standing on tiptoe, until one day (the first of June for me this year) they break. Pure washed-out, denim-blue standards, falls streaked with violet, a white throat on which sits a smudge of saturated egg-yolk yellow.
There are several flowers to a spike and they last for a good three weeks - up until the solstice if we don't get a hot blast of weather. I am also growing this plant with muskily scented Primula florindae in the mud of a pond in the Cotswolds and here, with all the moisture it desires, it is almost double the size.
I am currently growing it in preference to I sibirica, which was a hard decision, but in the end one that was made for me as the plants began to dwindle. I have grown Siberian irises since I was a child, as much for their foliage as their flower, which in truth is as brief as a dog rose. But I love their verticality and the fact that they stay where they are put, and I have played with several over the years to get to know the best. I had a deep blue form laced with gold on the falls called 'Emperor', but it came unstuck in the garden here, as things rose up over the years to shade it out. Although they can cope with a little ambient shade, the thing they seem to like least is close competition. Iris are designed to have their head and shoulders above the crowd. This is how they like to live and how they look their best.
I sibirica is pure china blue in the true form, but there are several that stand aside as highly desirable. In one garden I have teamed up the dark royal purple I sibirica 'Shirley Pope' with white Thalictrum aquilegifolium 'Album'. They are staggered through a low undercurrent of Geranium 'Ann Folkard', which has a bright lemony leaf and forms good company in that it prefers to live low and give the iris its head. I 'White Swirl' is the clean lemony white that they grow in the white garden at Sissinghurst, which is pure and unadulterated. Although I have not tried it yet, I couldn't help but admire 'Butter and Sugar' in Beth Chatto's garden last time I was there in June - a creamy yellow fall teamed with a white standard. When I move on from 'Gerald Darby' to continue this wonderful journey of getting to know the iris, it will be to the I ensata. There is a wonderful collection at Wakehurst Place in Sussex, towering at almost two metres, but taking up not much more than standing room on the ground. This is quite something to see. Real loftiness.
Altogether smaller in scale, so that you have to stoop rather than crane your neck, is Iris chrysographes. The species is variable; some flowers are veined with green like a snake, over a velvety brown base, but my favourite is the 'Black Form'. This is arguably as dark as any flower can be and the delicate flowers absorb light like coals suspended on wire-thin stems. When I have the space to enjoy it (for it is an iris I will come back to again and again as a favourite), I plant it through a veil of Bowles' Golden Grass, Milium effusum 'Auruem'. The pitch-dark velvety flowers are all the better for being suspended among the seedheads of the pale primrose grass and, though they last just a moment, it is one that perfectly closes this glorious prelude to high summer.