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IRIS
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Iris are available
between May and November from our Autumn Catalogue
or you can buy in season from our Online
Ordering Centre. |
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Please click on the
small pictures to see enlarged pictures which will open in a new window. |
This article is split into Iris for
Mixed Border,
Water side,
Semi-shade
and the Rock Garden.
There are
cultivation notes at the end.
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Introduction
Whether its a haze of flag iris shimmering in the heat of
Monet's garden or rimming his waterlily pool, a bowl of stylosa on a winter
windowsill or a bunch of Dutch Iris in a florist's bucket the word iris
conjures a host of different images. Not only do they flower for more than 6
months, from Nov-June, each has very different cultural requirements.
Appropriately named after the Greek goddess of the rainbow, they are found
wild throughout the Northern Hemisphere and have long been cultivated for
their colourful flowers. In Turkey one has always been used to decorate
grave yards whilst in Italy another is an important ingredient in the
perfume industry. I have seen them massed in high Himalayan bogs, clinging
to life on an arid Greek hillside and lining the banks of our local canal.
With such a disparate distribution there is sure to be an iris suitable for
virtually every part of the garden. |
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Iris danfordiae |
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Mixed border
The first iris that usually springs to mind is the flag or
bearded iris. These have a broad, fleshy rhizome on the surface of the soil
and a fan of grey-green leaves. They have a long history of cultivation and
even in the 17th century many hundreds of hybrids were recorded. Some of the
best known are still cultivated today such as the rich purple Iris germanica,
Iris g. Florentina (orris root) and the variegated form of the scented Iris
pallida. Although they all have relatively small flowers they are very
tolerant garden plants for any well drained soil in full sun. |
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Iris 'Langport Wren' |
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The large and
often dramatically coloured modern bearded iris has a complex genetic
history. They are architectural in form, carrying their large, flamboyant
flowers on upright stems. For ease they have been classified according to
height, from tall (70cm) to miniature dwarf (-20cm). Curiously their flower
size does not vary so dramatically, most being 3-6" across. They are easily
grown in a limey soil in full sun and their colours, covering a huge
spectrum, often contrasted or subtly mixed, means that there is always one
to match any colour scheme. I must admit that I choose them by colour and
not name, there are so many available. Although traditionally grown by
themselves I prefer them as part of a mixed planting and use them to back
our herb garden. Care must be taken to ensure that the rhizomes are in the
sun and not shaded by surrounding plants. In a wide border the intermediate
varieties, such as the almost red-black
Iris 'Langport
Wren', are perfect for the middle with some of the dwarf bearded
along the very edge. |
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One of the easiest, for a soil that is not too dry, is Iris
sibirica and its hybrids. They produce dense clumps of slender leaves topped
in May or June by a mass of dainty flowers. These may be blue, violet, white
or attractively veined. Their early flowering and neat habit even when out
of flower, makes them ideal for the mixed border. The lovely creamy-yellow
and white 'Butter and Sugar' is one of my favourites. The robust, 1m tall
Iris orientalis with its slender yellow and white flowers is ideal for a
dry, sunny border. Although by no means a showy plant every garden should
have a clump of the dwarf Iris graminea tucked into a corner. The slender,
deep purple flowers are almost hidden by the narrow leaves but they really
do smell of hot plum tart and are produced in such profusion that there are
plenty to cut. |
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I have not
mentioned the Xiphium ( Dutch, English and Spanish) iris as personally I
think these rather stiff florist iris can be difficult to integrate into a
border. Tight clumps of a single colour are the most effective way of
planting them, although that may take some effort to achieve as the bulbs
are usually sold in mixed colours only. One of the most effective
associations I saw occurred by chance. A solitary golden Dutch iris was
almost obscured by a cloud of violet aquilegia flowers that had seeded on
top of it leaving it rather like an exotic butterfly and beautifully
disguising its inherent stiffness.. |
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Water side
Iris are one of the easiest and most attractive of the marginal plants. Only
Iris laevigata itself must be grown actually in water all the time, Although
they make attractive pond side plants, Iris ensata and Iris versicolor will
also grow quite happily in any moist, rich soil that does not dry out and
preferably does not contain excessive lime. There are many named forms and
they come in all shades and mixes of blue, purple and white, including
double flowered varieties. Some of the most dramatic are the modern Japanese
hybrids which have unbelievably complicated marking, There is a fine
collection of them in the wild garden at at Wisley, a gift from a Japanese
student. I find them very vigorous and easy to propagate by division early
in the spring, although August is the more traditional division time for
these and most other iris. |
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The familiar
yellow flag iris of the water meadows. Iris pseudacorus, is much too
vigorous for most gardens. However the almost glowing golden leaves of Iris
p.'Variegata' are particularly beautiful in early spring. It can be grown in
an ordinary border, provided the soil is not too dry, and where it will be
of a more manageable proportion than if it was alongside a pool. I prefer
the delicate lemon flowered form which I grow beside my large pond where it
is mixed with Zebra grass and a golden rush. But no matter which form is
grown do not let them seed or they will quickly become a nuisance. I must
admit that I also find the blue Iris versicolor a little too generous with
its offspring. |
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All forms of
Iris sibirica love the moist soil beside a pond. They flower earlier than
the traditional water iris and are useful to extend the season as well as
adding yellow to the usual blue/white colour range. The shorter Iris
setosa also thrives in the dampness of a pond margin, producing its light
blue or violet flowers in early summer. I 'Gerald Darby' is much more
robust, producing a succession of strongly veined purple flowers on well
branched, almost black stems. |
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Dry, sunny borders
One of the joys of winter is the perpetual succession of blooms on my
various forms of
Iris unguicularis - still better known under the old name of
Iris stylosa.
Whenever the temperature rises above freezing for a few days they will
produce flowers, many hundreds over the season on established clumps. All
are native of the poor soils and dry conditions of the S. Mediterranean and
N. Africa and flower best when tucked in against a south facing wall. There
are many forms available but I still think
Iris 'Mary Barnard'
is one of the best. It is certainly the most floriferous. It has slightly
narrower leaves than the type and starts producing its rich purple flowers
early in November and, in cool springs, has been known to continue well into
April, although March is more normal. One common complaint is that
established clumps tend to be rather untidy in appearance. This can be
partially overcome by reducing the leaves to 2/3 their length in late autumn
and by gently raking out the dead foliage. This has the additional benefit
of also reducing the resident snail population that frequently causes
unsightly holes in the flowers. |
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Iris unguicularis |
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Iris 'Mary Barnard' |
A warm,
sheltered wall is also the perfect home for the slightly tender Iris
japonica. These have a broad fan of leaves and exotic pale blue or white
frilly flowers, dramatically splashed with purple and with an orange
crest. 'Ledger's Variety' is reputedly the hardiest form. There is also a
variegated form with attractively striped green and white leaves. Iris
tectorum is another crested Chinese iris for similar conditions. |
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Semi shade
Although iris are principally associated with full sun there are some
species that not only tolerate but actually thrive in cooler conditions.
Iris
foetidissima, called the roast beef iris after the smell of its crushed
leaves, is one of the most adaptable plants regarding soil or position. It
is is naturalised here in Somerset, often appearing in hedgerows, and can be
somewhat invasive. The plant that I enjoy most has seeded itself into a mat
of variagated vinca carpeting the base of a huge yew tree. I never notice
its slender leaves and certainly overlook the insignificant brownish flowers
that appear in April. Then in September the fat seed capsules open to reveal
glowing, sealing wax red seeds that remain on the plant well into the new
year, a perfect foil for the pale vinca. There is a variegated form, valued
as a foliage plant in its own right although it tends to be prone to rust if
not divided regularly. |
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Iris
foetidissima (berries) |
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Iris Broadleigh Carolyn |
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For many
years Broadleigh Gardens has been virtually synonymous with the evergreen
Pacific Coast iris. Often called "orchid" iris when we show them at the
Chelsea Flower show, they are the result of crossing various Californian
species. The resultant progeny have one of the widest ranges of colours of
all the iris, usually with a contrasting, veined mark on the falls. All
require a neutral to acid soil and are particularly effective used, as I
first saw them, lining a path through a rhododendron wood. Their subdued
colours are complimentary to those of the rhodos. Unlike most iris they
flower just as well in partial shade as full sun. The early flowering and
rather upright yellow and white 'Agnes James' and the clear blue 'Broadleigh
Carolyn'
would be among my first choices. Like most of the non-bearded iris the clump
gradually expands outwards from the center and should be divided at regular
intervals, discarding the central portion. We do this in late August. |
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Not all iris are showy giants, some of the real gems of the
genus are very small indeed. The tiny 6cm tall Iris cristata and the closely
related Iris lacustris also prefer a humus rich soil in partial shade.
Considering the size of the tiny rhizome, connected to each other by
thread-like stolons, their rather flat, blue or white, crested flowers are
remarkably large. They gradually spread outwards to form quite extensive
patches and are are best divided just after flowering. |
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Although Iris lazica is an
Iris unguicularis
relative it comes from the cooler Black Sea coast and prefers a semi-shaded
position, as we dicovered to our cost having struggled for some years to
grow it in full sun with our main Iris unguicularis collection. It is now
much happier in a shaded bed under a north wall where it freely produces its
narrow, heavily veined purple-blue flowers. |
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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. |
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Iris 'Harmony'
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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. |
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Iris histioides 'George' |
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Iris 'Edward' |
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Although not strictly speaking an iris,
Hermodactylus
tuberosus, the Snake's Head or Widow Iris, with its finger-like tubers
and velvety brown flowers is very closely related to Iris reticulata. It
will grow rapidly in a light well drained soil but will only flower well if
given a dry summer dormancy. Here it has become naturalised in grass under a
large oak which keeps it dry in summer. |
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Iris tuberosa
(hermodactyllis) |
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Iris bucharica |
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My rock bank is also home to two very dissimilar species.
One of the most unusual iris, both in and out of growth is
Iris bucharica.
It is the only member of the beautiful Juno iris group that can be grown
with ease in the open garden. Its strange, greenish yellow flowers rise
out of an interlocking fan of shiny apple-green leaves and come from a
rootstock that is half bulb and half tuberous root. It flowers in mid
spring. Flowering later in the summer is a dwarf, evergreen iris from the
Balkans and Turkey. Iris sintenesii is easily grown and deserves to be more
widely grown. At first glance the flowers appear to be a deep violet-blue
but a closer inspection reveals them to be a heavily veined white, which
gives them an almost metallic sheen. |
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Iris 'Blue Denim' |
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The dwarf bearded iris also find their home among other low
growing plants on the rock garden.. The strange Iris 'Forest Light' has
long inhabited my rock garden where its greeny-yellow flowers associate well
with the grey blue of
Ipheion
uniflorum. Another good combination is
'Blue Denim' with
Tulipa
batalinii 'Apricot Jewel'. Once again there are many hundreds of
varieties and colour combinations to choose from. |
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Tulipa batalinii 'Apricot Jewel' |
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Cultivation/ propagation
1. With the exception of the bulbous iris all should be planted with the
rhizome at or just below the soil surface.
2. Late summer is the best time to move or divide most iris.
3. When dividing iris reduce the rhizome to a young, vigorous piece,
discarding the old rhizome.
4. Water all iris in dry weather the first season after transplanting to
help them establish a new root system.
5. Plant bulbous iris 4-8" deep in autumn. Juno iris should only be planted
2" deep. Lift and divide bulbous iris as the leaves fade.
6. Most species iris can be grown from seed although some may take many
years to flower. Hybrid iris will not come true to name.
7. Feed with a low nitrogen, slow release fertilizer.
8. With the exception of water edge varieties iris prefer a well drained
soil. Add grit and humus to heavy clay soils. Lime may be beneficial for
very acid soils. |
