Named for the goddess of the rainbow, and forever associated with the rainbow's many hues, irises have a long history in gardens.
Valued in ancient times not only for their colors, but for the medicinal uses of their rhizomes, they are found in a mural
painted about 1500 B.C. in the great Minoan palace at Knossos (Crete).
Early Christian missionaries in Europe used the iris flower as a teaching device, just as they later used the Passionflower
in Brazil. A symbol of the French royalty (fleur-de-lys), of the Italian city of Firenza (where rhizomes were long grown commercially)
and of the city of New Orleans, the iris is still exciting today.
Hybridizing and breeding programs are producing new varieties in Bearded Hybrids, Siberians, Dutch Iris, Pacific Coast
Hybrids and Louisiana Hybrids, among others. Dedicated amateurs, small growers and large growers alike are actively looking
for the next great irises.
For us in the Northwest, the excitement includes the chance to see hundreds of varieties of bearded hybrid iris when the
world's two largest growers, Cooley's Gardens of Silverton, Oregon, and Schreiner's Iris Gardens of Salem, Oregon, open their
fields during the blooming season (see sidebar).
Although Bearded Hybrids tend to dominate discussion, many other iris are beautiful additions to the garden. There are
so many kinds of iris (200-300 species, let alone all the hybrids!) that my intention here is to help the gardener to sort
out the categories that might be available, either locally or from mail order nurseries, along with what to expect from each
Basically, iris are either bulbous or rhizomatous. The bulbous irises come from dry-summer areas around the Mediterranean
and in the Caucasus. They go dormant during the summer, an important point in placing them in the garden. The rhizomatous
irises are quite varied, and come from all around the northern hemisphere.
The form of the iris flower is fascinatingly complex. There are three petals that usually (but not always) stand up and
are called the "standards." Then there are 3 sepals that often (but not always) droop down, and these are called
the "falls." The falls have various pollination devices on them, such as the "styles," under which a bee
or other insect must creep to get nectar. Other devices that may be there are bright markings used as guides for the pollinators,
or there may be a pollen-bearing "beard."
Reticulatas. Among the earliest blooms of the year are the little (4-6") reticulata iris, along with their hybrids
and the yellow Iris danfordiae. They are usually blooming in Seattle during February and March with dark red-purple, blue-purple
or light blue flowers. All of their flowers have interesting color details in the falls. Plant them about 4" deep, except
for Iris danfordiae, which should go very deep - 8" is about right. Danfordiae has the bad habit of dividing after bloom
into dozens of tiny bulbs, none of flowering size, and planting deep seems to prevent that. The leaves will start to grow
out after bloom, eventually getting about a foot long. These little iris make good container subjects, and look at home in
the crevices between rocks. They do not need rich soil, and like to dry out during the summer.
Dutch, Spanish and English Iris. Blooming stems are 18-24" tall, and excellent for cutting. The leaves are not beautiful,
and after bloom should be allowed to dry out. This can be accomplished by planting them behind slow-starting perennials or
grasses (like asters, echinacea, or miscanthus) which will grow up to hide them in June. They often send up new leaves in
late fall and finish building up their bulbs during winter here. These iris come in deep blue and purple, lavendar, brown,
orange, yellow and white, with the English iris contributing wine red and maroon. But to list their colors hardly describes
the surprising bi-tones they achieve, exquisite or ghastly according to taste. Their styles are prominent, often contributing
a third color.
Rhizomatous iris are classified as Bearded, Beardless, and Crested.
Bearded Hybrids. These are the showy, May-blooming iris that are the stalwarts of the garden. They derive partly from
Iris germanica, and were often called "german" iris, but have been hybridized with so many species and varieties
that growers finally settled on "bearded hybrids." All colors except bright red have been produced, many in impossible
combinations, with edgings and stippling of dark on light, and light on dark. Newer selections show greater size, ruffles
and fringing, but many older flowers are kept on the lists because of a special grace of form or color blend, and some of
the most popular iris were bred decades ago.
A surprising number of gardeners consider bearded hybrids too much work, because every 3-4 years they should be divided
and the newest rhizomes re-set. I can only say, these folks need new iris. Iris catalogs are filled with rare beauties they
will look forward to seeing each spring. The plant itself is tough and self-reliant. It appreciates good soil and must have
good drainage. It needs moist ground during growth and bloom, and for a period after bloom while next blooms set. Then they
can go 2-3 weeks at a time without watering. Many gardeners do not water at all after bloom, but this leads to foliage deterioration
just when the strong grey sword leaves could stiffen up the blowsy look of the summer garden.
The bearded hybrids range in size from 6" miniature dwarfs through standard dwarfs, intermediates, border bearded
and miniature talls to tall bearded hybrids that may be 48". Growers are developing remontant (re-blooming) iris, but
be aware that they need summer fertilizer and water to achieve rebloom.
Arilbred Hybrids (bearded). This group includes some of the strangest iris you will ever see, and they sometimes pop up
at plant sales or from a neighbor. The flowers vary a lot, but the unusual ones that people treasure have "dotted lines"
all over the falls in un-flowerlike colors like brown, navy, grey or black. Care for them like bearded hybrids.
Siberian Iris (beardless). The beautiful grass-like foliage and easy nature of the Siberian group of irises makes its
lack of show a virtue. Even its seedpods are often so beautiful that deadheading seems pointless. The leaves are 16-36"
tall and the blooms rise above in colors of purple, blue, lavendar, wine, pink and white, usually with pretty detailing. There
is a widely available yellow/white form called 'Butter and Sugar.' The "Black Siberian" is Iris chrysographes in
its black form, one of several close relatives. Siberian iris like a rich soil and lots of moisture during the growing season.
Breeders are developing wider petals, which creates a "rounder" shaped flower. The size of the flower has been increasing.
Another trend of recent years is the development of distinct bi-tones, as in 'Superego' and 'Shall We Dance?'
Pacific Coast Hybrids and species (beardless). Here is one of the most spectacular groups of iris anywhere, native to
our climate, yet hard to find. The named hybrids that sell on sight, like 'Roaring Camp' and 'Lunar Eclipse' are slow to propagate,
and also difficult to bloom in pots, so they lack sales appeal. Seeds are sometimes available (Thompson and Morgan currently
has hybrid seeds) but the best sources are a few small growers who show up at invitational plant sales. The species are just
as hard to get as the hybrids. These iris like soil with lots of humus in it, but it must be well-drained, and watering after
blooming is not recommended. Don't let nearby plants encroach upon them. Mine seem happy at the front of an east-facing border
where they have little competition. Don't ever disturb them unless their roots are actively growing, which would be in spring
when you see new leaves growing and again in October and the first part of November. The reward for your care is 3" flowers
on 12-24" plants of evergreen foliage. The flowers, in all the shades of the bearded hybrids, astound with their watercolor
blends of gold with purple, red with brown and gold, blue and white with gold or navy or purple-black veining, blotching and
edging. Some breeders have selected pure colors -- they have charm but not magic.
Water Irises This is a cultural grouping, unlike the other groups here, which are interrelated plants. These are all beardless.
Iris ensata. The Japanese iris is one of the most admired flowers in the world, almost synonymous with Japanese water
gardens and Japanese art. It has huge blooms, sometimes 10" wide, with short standards and enormous falls. Colors of
white, blue, purple, pink and lavendar are often veined or stippled beautifully, with yellow blazes on the falls. Many have
standards that look just like the falls, giving a "double" effect. They like rich, moist soil, and while they are
often grown in shallow water, they need to spend winter dormancy above water. They do perfectly well in an irrigated garden
Iris laevegata is similar to I. ensata, but slightly smaller, and blooms are purple with a yellow mark on the falls.
Louisiana Hybrid Iris. This group, like the Pacific Coast Hybrids, is simply spectacular, with flat open blooms, fascinating
color patterns and veining. They include some very good reds, as well as purple, blue, gold and white. Alas, they are rarely
grown here with the exception of a variety called 'Black Gamecock' which is a commonly available pond plant. Hardiness does
not seem to be a problem. Perhaps we simply need to experiment with them more. Like other water iris, Louisiana hybrids can
be grown in well irrigated, rich garden soil. They are not evergreen here, and are somewhat late to start spring growth. I
imagine our chilly ponds are not at all what they get in the south.
Iris pseudacorus. The yellow flag, from Europe, has made itself at home in many wild places in the Northwest. It multiplies
very rapidly, and often "climbs out" of backyard ponds to establish itself in the garden. It is very tall (to 5')
and graceful, and the flowers, while proportionally small, are very bright yellow. A hybrid worth looking for is 'Roy Davidson'
which has purple and brown patterns on the yellow flowers. There is also a variegated form with yellow and green striped leaves
in spring, which change to all green during the summer.
Crested Iris These iris have a ridge or flap-like structure on the falls, in the place where a beard would be on a bearded
Iris cristata. A small (6") native of the East Coast, available in either purple or white, with open blooms that
come early in spring. Its glossy foliage grows on slowly creeping rhizomes. It prefers part shade, humus-rich soil and summer
moisture. Slugs and snails love it.
Iris japonica. Blooms early (late March) and continues a long time, with sprays of flat, heavily fringed flowers, pale
lavendar or white, marked with a ring of violet watercolor dots around orange runes on each fall. It has a lovely fragrance.
The leaves are broad and glossy and set off the sprays of bloom like a work of art. A magnet for slugs and snails -- I grow
it in a tall pot to protect it and also to enjoy its perfume more easily. The leaves arch over, making the plant appear 12-18"
tall. It enjoys rich, moist soil.
Iris tectorum. The Japanese roof iris is another glossy- leaf iris with a penchant for rich soil, part shade and slug
bait. We know from its name it can grow in roof thatch. It has an open, violet-blue flower with interesting markings.
A Few Other Iris (beardless)
Iris orientalis. A pioneer plant, often found in old farmyards in the Northwest, where it was fed with manure. It has
nice foliage like a pseudacorus, 4-5' tall, bearing spidery flowers of white with a golden patch on the falls. It needs rich
soil to bloom well, but very tough otherwise. From western Asia, it is considered a Spuria iris.
Iris foetidissima. A handsome 2' evergreen iris from Europe. Has small, quiet flowers which develop over several months
into heavy seedpods. These split open in fall to reveal brilliant orange seeds which look well all winter. It can take sun,
but also does well in dry shade.
Iris unguicularis. Often called the Winter Iris because it blooms November to March. It is from the Mediterranean, and
those who treasure it find a spot for it where it catches winter sun, but can dry off in summer. It has low bending, narrow
leaves, and the surprisingly large flowers are elevated on 6-9" tubes (not stems). The lavendar, pink or white flowers
tend to hide down in the leaves, and it is often recommended to cut the tallest leaves back in the fall. Another approach
is to pick the blooms and enjoy them in a vase. I would not have included it, but saw it this winter in Montlake and found
it very exciting.