I shall never forget seeing the striking Iris chrysographes high in the mountains of Yunnan. Although related to Iris sibirica I grow it as an understorey in a mixed shrub border where there is plenty of moisture available. It is a highly variable plant and it is well worth hunting for the best forms which have rich, velvety, almost black flowers.

Iris 'Edward'

Iris histioides 'George'

Iris Katharine Hodgkin

Rock Garden
 
As winter eases its grip on the garden so the first of the bulbous iris appear. These are members of the reticulata group. All produce narrow, triangular leaves and  a single, slender bloom, principally in shades of blue and purple, often with an attractively contrasting orange or yellow mark at the top of the fall. They are best planted in small clumps and are ideal for a sunny rock garden where they associate well with other early spring flowering bulbs such as crocus. I like to grow them through low growing grey foliage plants. Reticulata iris are naturally snow melt plants of the high mountains in the Middle East, conditions that are not easily replicated here. One of the principal problems is that after flowering the bulb splits into many tiny bulbs that can take up to 7 years to reach flowering size again. Deep planting (20cm) will discourage splitting however I'm afraid I take the lazy way out and plant a few new clumps each year. 'Harmony' and 'Edward' are two of my favourites. Sadly the very vigorous Iris histrioides 'Major' is no longer available although its rich purple form 'George' is proving to be a good substitute.  Alternatively you could try the unusual Iris 'Katharine Hodgkin'. Its exotic colouring of cream overlaid with a blend of light yellow and greeny-blue comes from its parents, Iris histioides and Iris winogradowii, the latter having also imparted its higher tolerance  of our climate making it a reliable, free flowering perennial provided you keep the slugs at bay.

The dwarf bearded iris also make their home on the sunny rock garden where their samm stature is perfect for the other low growing plants. They range in height from 4" to 10" and come in a kaleidoscope of colours, from simple single colours to amazing combinataions. 

Spring (January) catalogue- plants posted Feb-April

Dwarf bearded, species iris such as chrysographes, ensata, sibirica and winter iris ( I unguicularis or stylosa)

Autumn (June) catalogue - bulbs posted Sept-Nov

Pacific coast, reticulata and other bulbous iris

2. Dwarf Bearded Iris
Article published in The Garden April 2009

The genus iris is one of the most diverse and popular garden plants with flower shapes and colours almost as variable as their habitats. Iris were named after the Greek goddess Iris, the personification of the rainbow, in recognition of their rainbow hued flowers.  Iris species are found throughout the Northern temperate latitudes, growing in conditions as diverse as high mountains pastures to hot Greek hillsides.  This means that their cultural requirements are equally diverse, some preferring a cool water’s edge location whereas others require a hot dry situation. The bearded iris fall into the latter group. They have been cultivated since Classical times and depictions of them have appeared in literature and painting for more than 2 centuries. They are pictured in the palace at Knossos on Crete and the French heraldic device, Fleur-de-Lis, was an iris not a lily.

Iris germanica, the common flag or bearded iris, with its fat, surface creeping rhizomes and broad fans of deciduous leaves has been in cultivation for many centuries and has spread all around the word from its Iberian home. I have seen purple flag iris flowering in old oil drums outside a stone house high in Tibet and in gardens on the island of Chiloe off the coast of Southern Chile . There can hardly be a garden in UK without at least one representative of this group, whether it is the classic old purple flag or one of the spectacular modern hybrids with their amazing colour combinations.

Iris breeding took off in the late 19thC and by the early part of the 20thC whole beds were devoted to them. Unlike the simple species modern hybrids have an improved elegance of form, with multiple buds to a stem and beautifully proportioned flowers. The standards are large and upright while the falls are full and flaring but it is their marvelous range of colours that really sets them aside. No visitor to the Chelsea Flower Show can fail to marvel at the spectacular colour combinations displayed on the specialist iris exhibits. 

Unfortunately, however seductive their flowers may be, TBI are not quite so easy to integrate into our modern style of gardening. They all need a well drained, rather poor soil and a situation where the sun will fall directly on the rhizome for most of the time if they are to flower well. They became a popular choice for narrow beds under a sunny wall which could be devoted to them. However their all too brief flowering period, and the hard work involved in the annual division of the rhizomes has meant that they are perhaps not as popular as they once were and the classic iris bed is a disappearing feature of our gardens. 

Bearded Iris are useful to fill that awkward gap in flowering after the tulips fade and before the majority of the herbaceous perennials start but successful integration into a mixed border is difficult. Here the soil is more fertile than they truly like and any competition or shade from neighbouring plants curtails their flowering. Although their flowers are tall they need to be grown at the front of the border to maximize the sun on their rhizomes and it is therefore not possible to hide the rather large holes left at the edge of the border when they finish flowering.

However their dwarf cousins are much more versatile and distinctly underrated as garden plants. They have an equally long and complex history and are the result of crossing naturally dwarf species such as I. pumila (eg I.pumila ‘Atroviolacea’), with the modern tall bearded iris. Breeders divide them into 2 groups depending upon their height. The Miniature Dwarf Bearded (MDB) are 10 - 20cm tall whereas the largest group, the Standard Dwarf Bearded (SDB) are between 21 – 40cm tall. This is an entirely arbitrary classification and there is no difference in performance between the 2 groups.

The first hybrids had clear, single colours such as blue, purple or yellow eg  ‘Stockholm’, ‘Mary McIlroy’*, ‘Zero’* and ‘Open Sky’, their beauty being in their dwarf stature but then gradually patterns, first as veins, known as plicates eg ‘Dunlin’ and then stronger contrasting marks appeared eg ‘Meadow Court’.  Finally the colours merged rather like an untidy artist’s palette where all the colours blend into each other often in a dramatic manner eg ‘Quark' , 'Peach Eyes' etc  

Although they are dainty and rather delicate in appearance they are fully hardy with a good  balance between leaf and flower, the flowers being 2-3” diameter, the best having well rounded, upright standards and falls that are held horizontally, not curving under, so that the patterns are visible; especially important as they are to be viewed from above. They flower for about 1 month in late spring (April-May) just before the TBI. Most have only 1-2 flowers on a single stem but each established plant can be literally smothered in flowers. There are some so-called Remontant forms but I have yet to find one that is truly repeat flowering. There is just an occasional late summer flower. A truly remontant iris with good flowers may come in the future. 

All are easy to grow provided a few simple rules are followed. They are shallow rooting and should be planted in a sunny, well-drained position, preferably in poorish soil with the rhizome on the surface and the roots extending downwards. Care must be taken not to allow neighbouring plants, or weeds, to encroach and smother the rhizomes. Congested clumps should be divided in late summer. The old central rhizomes should be discarded and the side ones replanted. Cut the leaves back by 50% and firm the roots well.

If you should have one, they are perfect for planting in front of TBI in a dedicated iris bed where they will flower first. Alternatively they are particularly attractive under a sunny wall, or against the house with other sun lovers such as Iris unguicularis, eucomis, nerine etc., where their fans of leaves provide a good foil for the other plants and where they fill the gap in flowering between I.unguicularis of winter and the late summer/autumn flowering eucomis & nerine. They are also very effective in the narrow beds that are often found edging the path leading to the front door, where they associate well with other low growing plants, especially those with silver foliage or Helianthemums. Smaller tulips are other good companions as they like similar dry sunny positions. [example the walled garden at Wisley].

Their dwarf stature makes them ideal for a sunny herbaceous border where they make a good edging plant. Although, like their tall cousins their rhizomes must be left exposed, they are much smaller and therefore their leaves are closer together and they make rather attractive clumps of foliage along the front edge. As DBIs are individually small it is advisable to plant at least 3 or 5 rhizomes initially to form a reasonable sized patch. Single plants in a border are easily swamped. Take care to keep any mulch away from the rhizomes.

For tall bearded iris contact:
Seagate Iris   
Kelways of Langport   

3.Winter iris
Article published in Gardens Illustrated Feb 2011

Brisk walks, warm fires and plant catalogues sum up winter, a time of bare branches rather than brightly coloured flowers but there is one group of plants that defy the elements to produce their jewel-like flowers in this most inclement time. These are the surprisingly sturdy winter flowering iris. There are 2 distinct groups of these – the rhizomatous I. unguicularis which flower from October to March and the bulbous  I.reticulata group which flower in late winter.  

The star of the winter garden is undoubtedly Iris unguicularis, still more commonly called by its old name Iris stylosa. This clump forming iris has tiny rhizomes and long, narrow, sword shaped evergreen leaves. It grows wild throughout the Mediterranean area where it is naturally winter flowering. It is extremely variable both in flower colour and size. It is native to dry, sunny soils and flowers best against a sunny wall where it can be left to form large clumps.

 The flowers are a typical rounded rather open iris shape in shades of blue-purple with a striking white and gold centre to the falls.  In the best forms these will start to appear in November and continue throughout the winter until they finally run out of steam in April. A cold snap with frost will halt flower production for a day or two but normal service is quickly resumed once the temperatures rise again and there is almost always a few to pick for the house. These are best pulled when in bud rather than cut. They quickly open in the warmth of a room and are one of the most cheering sights for a gloomy winter.

 Of the blue cultivars ‘Mary Barnard’ is one of the most vigorous. It is slightly smaller in stature, has narrower leaves and flowers of an intense rich purple. One of the most distinct is ‘Walter Butt’ which has very large flowers of the palest slate blue. The highly sought after white forms are often rather disappointing.  Unfortunately the smallest– I.cretensis,  ‘Oxford Dwarf’, and the slightly taller ‘Bob Thompson’ and ‘Abington Purple’ are also less hardy than the type and are probably best grown in a very sheltered position or under glass. These are only 4-8” high with more grass-like foliage.

The leaves of evergreen iris still die off regularly to be replaced by new ones. The overcrowded rhizomes and their associated dead foliage found in most mature clumps are the perfect hide away for snails which have an annoying habit of chewing holes in the unopened buds. This damage can be mitigated by reducing the leaves to about 8” in October and vigorously ‘combing’ through the clumps with a hand fork to open them up and to remove as much of the debris, and the resident snails, as possible. Congested plants should be lifted and divided, the old dead rhizomes removed and young pieces of the plant replanted with the rhizome at the surface of the soil and the roots placed downwards. This can be done either in August, when you will lose a flowering season or in early spring which is when we usually do it as it also lessens the risk of frost damage to the newly planted iris. Whenever you chose to do this the new plants must be regularly watered for the first year while they establish their root system.

 Reticulata Iris

The other group of winter flowering iris could not be more different. Instead of the mild climes of the Mediterranean basin these tiny iris come from the high mountains of the Middle East where they are buried deep in the snow all winter.  I. unguiculalris is naturally winter flowering but these flower as the snow melts in their Middle Eastern mountain homes and the temperature rises. In our gardens this means late winter – early spring; the first coinciding with the last of the snowdrops. Instead of clusters of surface rhizomes reticulata iris have a small pointed bulb, with a whitish netted tunic. They produce solitary flowers and long thin deep green leaves which are triangular in cross section. They are 4 - 6” tall.

 There are various species that make up this section. I reticulata is a very variable plant and most of the cultivars in commerce are wild selections. Iris histrioides has much bolder flowers. Sadly the best known form of this, I histrioides ‘Major’, is no longer available but other cultivars are just as easy. There are a few excellent hybrids.

 
It has always been recommended that reticulata iris should be planted on a sunny rock garden. But in this position the bulbs have an annoying habit of splitting into tiny non flowering bulbils so they are often treated as annuals. However one year I planted a flowering potful of iris in a new shady bed where we grow snowdrops - just to give it some instant colour (the garden is open!) and I noticed that they flowered just as well the following year. I now have well established clumps in cool, humus rich soil under deciduous shrubs so there is plenty of light/moisture when they are growing but dry and shady when they are dormant. The buds will poke through in December and then wait until Feb to flower.

 Their early flowering means they also make excellent subjects for pots for greenhouse, conservatory or house. The pots should be kept outside (protected from severe frost )until the buds appear when they can then be brought in to the house to flower.

  Cultivation: The bulbs are planted in the autumn in small groups of 5 – 10 bulbs 4 - 6" deep. They are traditionally grown as rock garden bulbs in a sunny situation but the dry soil usually causes the bulbs desiccate and to split into tiny bulblets which will then take some years to regain flowering size. Extra deep planting and feeding with a low Nitrogen fertiliser is often recommended to overcome this. However bulbs that are planted in a cooler, but equally well drained, position among shrubs do not split up in the same way and will continue to flower year after year. They can be grown in light grass under trees and are excellent subjects for growing in containers and make attractive pot plants to bring indoors once the buds appear.

Pests: these early flowers are like caviar to slugs who will leave unsightly holes in the petals. The bulbs can suffer from Ink Spot disease. Infected bulbs should be thrown away.

I.danfordiae This is the first of the group to flower with very angular yellow flowers with green spots in the throat and virtually no standards at all – just a vestige between the 3 falls. It tends to less reliably perennial than the others. More inclined to split. Mountains of Central Turkey   Height: 5"

I.histrioides ‘Major’ AGM wild central Turkey.This reliable cultivar has large deep blue flowers. Sadly this once popular bulb is no longer freely available but there are other good, similar cultivars. ‘Angel’s Eye’ (‘Angels’ Tears’) and ‘Lady B Stanley’ are recommended. Height: 5"

 I.reticulata

This very variable early flowering iris grows wild in N Iran to C Turkey where it flowers as the snow melts.  Over the last 100 years many colour forms have been selected. The following are some of the best cultivars. ‘Alida’ (illustarted)– is a new cultivar with exceptionally large mid-blue flowers. Good in pots; ‘Cantab’.-pale Cambridge blue; ‘Edward’, intense bright blue with a distinct orange ridge; ‘George’ AGM is a hybrid with I.histrioides and has exceptionally large flowers of rich purple; ‘Harmony’ has well-shaped flowers of a good clear blue and is scented. It is recommended for pots as the leaves remain short at flowering:  ‘Pauline’ deep purple with a distinctive white central stripe. Height: 6"

Whites – there are some rather pathetic off white cultivars but they are very weak. There are also some new hybrids with amazing colour combinations which are not yet commercially available so their vigour is yet to be tested but they are worth looking out for as they make a beautiful pot plant

‘Katharine Hodgkin’ AGM

An amazing hybrid between I.winogradowii and I.histrioides. It is much more vigorous than many of the cultivars and has significantly larger bulbs. The flowers are an extraordinary mix of cream and yellow overlaid with blue and green. It sounds dreadful but is very beautiful in the flesh. If planted in shade it will form large long lived clumps. Height: 4". ‘Frank Elder’ – similar with less yellow in the falls.  ‘Sheila Ann Germany’ is another hybrid of similar parentage and vigor with very large flowers of clear sky blue.