A to Z
Border Bearded Iris (BB)
Border bearded iris are the same as tall bearded iris in all respects, except their stature, and the same qualities should be looked for in them as in their taller cousins. The height range is similar to that of intermediate bearded iris, but the most common height is likely to fall in the upper range of 41 -70cm (16 -27.5 in). The fact that they are shorter than tall bearded iris means that they rarely blow over, and do not usually require staking. In many cases the shortness of stature is accompanied by slowness of growth, and it is rare to find an extremely vigorous cultivar, however, they are a very beautiful addition to the middle or front of an iris border. Being somewhat less vigorous than tall bearded iris, they do not require such frequent lifting and dividing, and so are also excellent plants where the planting is more or less permanent.
Colour break (CB) means when a new colour or colour pattern has been developed by hybridizing. The most recent breakthoughs have been in 2 locations in the USA, where random striped patterns have been developed in Utah, and luminata patterns (a dark colour wash over a light ground, where the lighter coloured veining shows through) in Oregon. The one colour break that is eagerly awaited is the development of a "true" red, but that is only really likely by genetic interference.
Intermediate Bearded Iris (IB)
Intermediate bearded iris are those which fall between the dwarf and tall bearded iris in both stature and season of bloom, which in much of the UK, is from early May to the beginning of June. The height of the flowering stems is between 41 -70cm (16 -27.5 in), with the majority being 50-61cm (20" to 24") tall. The IB plants are generally compact and vigorous, making them ideal subjects for the front of the sunny border. Their season of bloom, coming as it does as the tulips and the majority of spring bulbs are going over, and before the summer flowering starts, makes them a perfect link between spring and summer. The colour range is now similar to that displayed by tall bearded iris, with the additional advantage in many cases of having "thumb-print" marks on the falls, which creates a further dimension to their beauty. Their short stature makes them ideal for windy sites, as they do not blow over, and hence do not require staking.
Miniature Dwarf Bearded Iris (MDB)
The miniature dwarf bearded iris is not only the smallest, but also the earliest of the bearded iris to bloom. They grow to 20cm (8"), and bring lovely colours into the garden from March into April. In the rockery they can bring pockets of colour of deep blues and violets, bright and pale yellows, pale and mid blues, whites, and with modern hybridizing there are now also oranges, apricots and pinks available.
Stems usually carry two flowers, but many more modern varieties now have three buds, which all goes to prolonging the flowering time.
Miniature Tall Bearded Iris (MTB)
The MTB is exactly as its name implies, a miniature version of its majestic cousin the tall bearded iris. Of a height that lies between 41 -70cm (16 -27.5 in), in most respects it parallels the TB, but in smaller proportions, being multi-branched and multi-budded, but with slim stems and making neat and floriferous clumps.
Ideal for smaller gardens and frontal planting, it has a longer flowering period than most median iris, and blooms towards the latter end of the iris season along with the TB's. Once called "table iris" because they were dainty enough to use in flower arrangements, this class of iris has long been neglected by plants breeders, but deservedly, they are now receiving much more of the hybridizers' attention, and more new varieties are becoming available from specialist growers.
The reblooming abilities of iris are at the stage roses were some 80 - 100 years ago. Fortunately, in the last two decades a number of breeders in the USA have made concerted efforts to produce new hybrids that will rebloom, but not happy to rest on their laurels, some are now hybridizing for rebloom in colder climates.
When one thinks of rebloom, it is usually with a second set of spikes sometime between August and October, but if the genetic makeup and microclimate in which the iris are grown is conducive, then rebloom can occur at almost any time of the year.
Bearded iris are what are expected to rebloom, but in recent years some Siberians have exhibited this tendency as well. If you can get iris to rebloom, then you will be getting more value for your money and for your garden space.
Space Agers are named as such, because they came to prominence during the Space Age (i.e. the late 1970's), but in fact have been around since man first started helping nature by doing some pollen-daubing of his own. What makes them so different from other iris is that the rib that extends from the end of the beard down the fall has lifted from its bed, curving up into a horn. Past hybridizers made crosses to enhance this characteristic, and initially managing to lengthen the horn, eventually succeeded in getting it to curve back on itself to form a hook, flattened the end to give a spoon, and even flattened the whole horn forming a flounce.
Standard Dwarf Bearded Iris (SDB)
Most plants of standards dwarf bearded iris will have three buds, and their bloom time overlaps and follows on from the miniature dwarf bearded (MDB) iris. They bloom at a height of between 21 - 41 cm (8 - 16in), some varieties blooming earlier than others, so SDB's can give colour in the garden from April through to May.
All the colours exhibited by MDB's are available in the SDB form, and there are also many different colour patterns. These lovely irises make compact and colourful plants for the front of the border, and like all bearded iris, they like as much sun as they can get, and should be positioned accordingly.
Tall Bearded Iris (TB)
The Tall bearded (TB) iris, so called because they are over 71 cm (27.5 in) or more in height, are generally regarded by their supporters as the aristocrats of the iris family.
They flower, on average, from mid-May to mid-June, at a time when colour in the border is scarce. They are hardy, and will succeed in most soils, but avoid frost pockets. They are greedy feeders, and will amply repay liberal dressings of manure or compost, buried a spit deep when planting, plus an application of general fertilizer each spring. Be prepared to stake the stems in exposed situations, and to split the clumps every 3-4 years.
TB's require adequate drainage, and as much sun as you can give them. They should never be buried, and the upper surface of each rhizome should be visible, not only after planting, but throughout its growing life. Because most of the hybridizing work on irises over the last 100 years has been carried out on TB's, they now come in a very wide range of colours, colour combinations and patterns, including new forms such as Space Agers and varieties with new colour breaks. They are equally at home on the show bench as they are in the garden, and as the estate agent might say, "no garden can be considered complete without them". Better still, have a collection displaying the wide range of rainbow colours, forms and patterns now available.
These are bearded iris which are comprised of two species, I onco-cyclus and I regelia, the former probably being the most exotic looking iris to be found, having heavy veining and a dark blotch on the falls. There are inter-species hybrids, which have been named (e.g. Clotho and Thor), but none can be garden grown in the UK because of their cultural requirements. They are endemic to the middle east, where they grow naturally in the mountains and desert, and have evolved to cope with the hot summers, (when they go dormant,) and the cold winters, conditions we can only emulate by growing them in a cold greenhouse or frame.
Their culture is very demanding, but very rewarding when they do bloom.
Arilbred iris are hybrids of the better known bearded cultivars, and the more exotic "aril" iris. Arilbreds are, however, much easier to cultivate than their oncocyclus or regelia parents.
Modern arilbred varieties resemble their aril parents closely, the blooms often exhibiting striking "onco" characteristics of form, veining, spectacular signals and beards.
They can succeed in the open garden where the bed should be well drained, the soil light and open, and the aspect sunny and sheltered. They are cold hardy in the UK, but resent excess damp and stagnant air. They grow extremely well planted in large containers in a cold greenhouse.
Formerly known as I. kaempferi, but now known as I. ensata, these plants are, with I. laevigata, the oldest iris cultivars. They were described by a poet in the 12th Century, while cultivation and breeding certainly occurred in the 17th Century. They are closely associated with water, but are best grown at the damp edges or streams or ponds, rather than actually in the water. In flower beds they need plenty of water from the first signs of growth in March until flowering is over in July. Although their height is fairly consistent at around 90-100cm (35"-40") flower size and form varies, but the characteristic shape is rather flat with all the petals in one plane. Colours vary from whites to reds, from blues to violets, but there is no natural yellow, and patterns vary from solid colour to one overlaying another in stripes, dots and dashes. They are members of the beardless group of iris.
Anne Blanco White
The leaves of these iris look like sweet corn, and they have fleshy storage roots which must not be broken. Of the 50 species, only seven are known to be hardy in the UK, but not many are available, the majority being in small private collections which are grown in a bulb frame or pots in an airy alpine house using compost which should be 75% John Innes no.3 with 25% grit. Some of the species (e.g. I nicolai) will not take overhead watering, so they have to be grown in a pot within a larger pot, watering the outside pot only. The most commonly Juno available is I bucharica, and it is fairly typical of the type. I cycloglossa is a tall hardy blue with upright standards, unlike most Junos which have reduced standards which are not often upright.
If you have a pond, then the beardless laevigata iris are a "must". They grow in damp soil, or water up to 10cm (4") deep. Even if you do not have pond, the conditions they require are easily produced with cheap sheet polythene, or even an old washing-up bowl. They are easy to grow, and thrive in good garden soil, which should not be too chalky.
The original common variety has rich blue three petalled flowers, and grows to a height of 24" (60cms), but newer hybrids are now being produced in different shades of blue, mauve and white, and there are even some cultivars with 6 falls and no standards, which resemble some types of I enstata.
Louisiana Iris (LA)
These iris are endemic to the state of Louisiana in the USA, having evolved to accommodate the local climate, which is very cold and frosty in the winter, and very hot and humid in the summer. LA species grow in ditches, which were dug to deal with the run-off of floodwater after heavy rain or as a result of thawing snow, so the plants are very hardy. It would appear that with similar conditions in the UK, they could be grown over here, but we do not normally get temperatures high enough to bring them to their full potential, and most people who do grow them have to be satisfied with somewhat stunted growth.
They have, however, become widely distributed in the USA and Australia, because the growers have been able to supply suitable conditions, and a lot of hybridizing has been done on LA's, producing large flat iris in almost as many colours as the TB's.
If you fancy a challenge with these beardless iris, then give them a try.
Pacific Coast Iris (PCI)
The Pacific Coast, or Californian iris are members of the beardless group, and comprise a number of iris species, mainly I. innominata, I. douglasiana, I. tenax and I. munzii, all of which are endemic to the west coast of North America. It would be difficult to grow most of the species in the UK, but hybrids bred from inter-species crossing are usually quite easy in British gardens. They are best grown from seed, which should be sown in trays in the autumn, and left outside over the winter. Germination is high, and under the right conditions, some plants can be expected to bloom in 18 months, exhibiting a variety of colours, and even with delicate tracery in the petals. A warning. Mature plants hate being moved, and this exercise should only be undertaken in September/October, when they are forming new roots, and disturbance is minimal. Otherwise, they are very accommodating.
Reticulata iris are the bulbous iris that bloom in February, and are the harbingers of spring, the name being derived from the loose "net like" skin that covers the bulbs. Most species have a quadrangular cross-section to their leaves, and flower up to 15 cm (6").
The ten species grow best in a well draining bulb frame, or in deep "long tom" pots in a cool greenhouse, using John Innes no.3 compost with added grit. The species I reticulata, histrioides and winogradowii, and all hybrids will grow outside in a sunny, well draining spot, rock garden or border, with I winogradowii requiring a richer humus soil, and more moisture when dormant. The bright yellow I danfordii needs deep planting to stop the bulbs breaking up to "rice" bulblets.
Siberian Iris (Sib)
These are excellent garden plants from the beardless group of iris, easy to grow in most soils, and any position that is not too dry, but fairly sunny. They combine very well with other border perennials, especially aquilegias, campanulas and hardy geraniums, which also flower in May and June, and there are some repeat-blooming Sibs which extend the flowering period. Most Sibs are descended from hybrids between I sibirica and I sanguinea, and grow in the main to 75-90 cm (30"-36"), but there are also some dwarf cultivars. Colours include all shades from blue to violet, as well as purple, lilac, wine-red, lavender-pink, white, yellow, and more recently black. The older cultivars had drooping falls, but in moderns ones they tend to be horizontal, but either way, they all have their own charm.
This is another beardless group closely related to the Siberian iris, and includes I chrysographes, best known in its "black" form, of which there are now a number of named hybrids. Some of the other species in this group are I forrestii (yellow), and the taller I delavayi (violet). Few hybridizers seem to have succumbed to the charm of these iris, but the work that has been done, produced first of all spotted patterns of blue on a white ground. Further work has introduced colour into the ground, and more recently the dotted patterns are blending into one another giving an ombre effect.
These also need moist growing conditions, in an acid to neutral soil.
There are, at present, 27 different groups of wild irises, mostly containing a number of separate species which are more or less easily recognizable. Many of these plants come from endangered habitats in countries with very different climates from our own. It is important that when seeds or plants are brought here we should try and establish ways of keeping them growing, breeding new generations and maintaining as wide a genetic base as we can, and information about such procedures needs to be published.
If you are not afraid of a little science, and would like gardening which stretches your mind as well as your muscles, then specie iris and the Species Group are for you!
Anne Blanco White
With all their frills and furbelows, tall bearded iris could be considered the queen of the garden, but if that is the case, then with their understated elegance, spuria iris must surely be the king.
Spurias are beardless iris, and are the penultimate to bloom. They are truly border plants, as they resent disturbance, and can be left to their own devices for 10-15 years, with little more needed than to cut back the stems after bloom, tidy the foliage in the autumn, and supply a dose of fertilizer in both spring and after bloom. Spurias tend to be tall (one noted hybrid grows to about 2M), work well at the back of the border, and even after bloom is over, their upright leaves become an excellent foil for other plants in front.
Not all spurias are tall however, as species such as I graminea pseudocyperus only grow to 30-38cm (12î-15î), which makes it good at the front of the border.
If the weather were to get warm enough, some spuria hybrids would become summer dormant, but there is little likelihood of that happening in the UK, so we can continue to enjoy their foliage until the autumn rain cuts it back in preparation for the following yearís growth.
This Algerian evergreen iris and its named cultivars flower during the winter months, often providing blooms for the Christmas table. The flowers of the species are lavender blue with lavender veined white patches on the base of the falls, and a golden stripe along the rib. The most common cultivar is MARY BARNARD, which is a deep lilac, but there are other cultivars which cover the colour spectrum from pale lilac to deep purple/blue. There is also a pink hybrid from New Zealand, and a white version, which retains the gold rib on the falls.
The closely related I lazica has wider leaves, and the sub-species I cretensis has very narrow grass-like leaves, and smaller delicate flowers. Other cultivars include marbled and striped forms, which are available from specialist suppliers.
The bulbs are usually slightly larger than the reticulatas, and have a smooth tough skin. The leaf cross-section is semi-circular, and the stems are taller to 25-90cm (10"-36"). Five of the seven species are on the tender side, and are best grown in a bulb frame or alpine house.
I xiphium and its forms (the Spanish iris) will grow in a sheltered, sunny, well draining border.
Hybrids with other species developed the "Dutch" iris so beloved of florists. These will grow in any rich draining soil in the border among shrubs, or under light shading trees.
I latifolia with a wide range of blues, purples or whites require a damp, but not waterlogged spot. Although they are from the Pyrenees, they are called "English" iris, but are sadly short lived, and prone to virus.