Iris - Rainbow Flowers

Iris germanica, Bearded Iris are hardy perennials producing fans of leaves from a creeping rhizomous root and amazing, fragrant flowers. The Iris rhizome root is the source of Orris root. The essential oil, Orris Absolute Oil rendered from Iris rhizomes.

This has a sweet scent similar to Violet which is used as an essence for perfume and in an earlier age was given medicinally as a sedative. The Orris root is also used to flavour some types of Gin and the flowers are used to give it colour. The flowers have six petals: three upright ‘standards’ and three hanging petals called ‘falls’. Each fall has a fuzzy line or ‘beard’ running down the middle of each hanging petal which gives this elegant flower its name of ‘Bearded’ Iris.

The Bearded Irises of today’s gardens are a natural hybridogenic cultivar of European origin between the wild species Sweet Iris (I. Pallid) and the Hungarian Iris (I. Variegata). All the many thousands of named hybrids and varieties are a result of continuous cross-breeding between these progeny. Bearded Iris has been cultivated since ancient times in Europe where they are known as “German” Bearded Iris. One of the original wild species rather closely related to Iris germanica was adopted by the Kings of France as their emblem: the Fleur-de-lis.

The name ‘Iris’ is from the Greek word for ‘rainbow’ in illusion to the vast colour range of these flowers.  Goddess Iris is the Goddess of the Rainbow; a patron Goddess especially of women who guides their spirits to heaven via the rainbow. She is also the communicator and messenger bringing messages from Heaven to Earth. Thus in the Language of Flowers the Iris is the symbolic Messenger of Faith, Health, Hope, Love, Purity (especially meant for white Irises). It is often planted in ones garden when these qualities are sought or given to others as a symbol of these sentiments.

There are tall, intermediate, semi-dwarf and dwarf species depending on how tall their flower spikes grow. Flowering reaches a peak in Mid to Late Spring and some varieties bloom again in Autumn. A few species even bloom during the Winter months in mild and subtropical climates. In temperate climates with distinctive seasons, Bearded Iris can be grouped into early, mid and late blooming varieties. The shorter Iris varieties normally bloom first and the tallest ones last. Not all Bearded Iris species and varieties will flower as well when grown in warm subtropical districts with a ‘winterless’ climate, and those that do are liable to flower whenever they choose.

Miniature Dwarf Iris grows about 20cm/8inches tall. They are very early bloomers with a good colour range with perfectly formed blooms that are usually fragrant with just a few flowers per stem. These are wonderful clumping plants for the border or rockery and do very well in containers.

Standard Dwarf Bearded Iris produce plants 20cm/8in-41cm/15in tall. These are the next group to flower in the Spring. They often flower at about the same time as the traditional Spring-flowering bulbs and are a wonderful combination when planted amongst them all.  Their colour range and fragrance is exceptional.

Intermediate Bearded Iris grows 41cm/15in-70/28 inches tall. These usually flower following the spring-flowering bulbs or with the late Tulips on stocky plants with many beautifully colourful, fragrant large blooms that are very disease resistance and weather-proof. They are great for cutting, very hardy and hardly ever suffer from wind damage.

Miniature Tall Bearded Iris is the same height and flower at the same time but their stems are somewhat thinner and more branching with more flowers per stem that last longer. These come in almost every conceivable colour, are delightfully perfumed and make excellent cut flowers. They soon create large clumps which are truly elegant when in full flower.

Border Irises are almost identical but bloom a little later on branching clumpy plants.

Tall Bearded Irises are 70cm/28in or taller. These are the elegant ‘Queens’ of the Iris Kingdom producing huge, often ruffled or plumy blooms with up to 9 to even 14 flowers per branching stem. Their exotic and very fragrant flowers can measure 6in/15cm across and as high on graceful tall stems creating a truly stunning picture. The old-fashioned varieties produced fewer blooms that did not last nearly as long as the much improved modern hybrids. These are elegant for cutting and display. They are the last to bloom and are generally weather resistant. Although when over-fed, and grown in loose soils, they can become so tall and top heavy that they flop in heavy rain and wind. Exhibition Growers often stake these prized blooms. There is no question that a fully mature clump of Tall Bearded Irises in full bloom is an unforgettable sight!

Dependent upon variety, some plants produce several branching spikes from one rhizome while others produce a single stem. The exotic blooms usually carry a lovely perfume and make superb cut flowers, especially the intermediate and taller forms. Colours cover the rainbow in an exquisite array of shades and combinations giving rise to the common name of “Flag” Iris or “Rainbow Flower”. The only shade missing is true fire-engine red, although there are a multitude of brick and burgundy red shades, copper to orange-red, scarlet red to deepest black purple red and wine red shadings. By far the finest Irises are in blue and purple shades, also pink and salmon; bronze, copper, orange and yellow plus pristine white and an infinite array of combined colour shadings.

They do especially well in temperate climates of Europe and much of the Northern Hemisphere or almost anywhere with a cold Winter, warm Summer and dry Autumn. Many hardy varieties will flower anywhere in the cool, Mediterranean climates like New Zealand’s, even in the humid subtropics if give good drainage and a bright but cooler exposure.

Soon after flowering simply cut the old flower spike down to the ground, leave the foliage intact so that it can help foster the growth of new side shoots that will produce next year’s blooms. Usually later in the season once the new growth becomes established, the older growth around the dead flower stem withers away leaving only the old rhizome connected to the new growth.

Each rhizome blooms only once then produces new rhizomes for next years’ flowering. These start as small eye shoots which sprout off the sides of the mature parent rhizome. The shoots quickly develop into a fan of flat, long, strap-like leaves that come to a soft spear-like point. Then the brown, flattish and fleshy rhizome begins to develop beneath and behind the fan of leaves. This slowly extends outward on either side of the old parent plant.  Feeding roots begin to extend down into the soil from the rhizome which feeds the growing fan of leaves.

By Late Summer or Early Autumn the new rhizome and fan of leaves is nearly mature and then enters a semi-dormant period which continues until flowering the following Spring. Usually this fan of leaves remains semi-evergreen right through the Winter. But in cold climates experiencing severe freezing the leaves often wither way leaving only the rhizomes with a small eye shoot or just a few leaves remaining that will produce the next flowering in Spring. These are often some of the first green vegetation to reappear in Early Spring.

Bearded Iris plants are best moved right after flowering or when the new rhizomes have matured later in the Early Autumn. Certainly early planting directly after flowering insures that new growth will become well established for the following year’s flowering. This is especially true in colder climates. In very mild climates with little winter freezing, Bearded Iris can just as easily be transplanted in Autumn once the new rhizomes have matured. Because limited root growth will continue right through the Winter, these plants often still flower successfully the following Spring.

Bearded Iris creates a creeping rootstock that continually grows outward from its central starting point. The rhizome always produces its fan of new leaves at the end of the rhizome facing outward from the central clump. Then after flowering, side shoots appear on either side of the parent fan and continue spreading outward and away from the parent. So it is best to dig and divide maturing clumps every few years; as the centre of the clump begins to die out. As mentioned earlier the best time to do this is right after flowering or in Early Autumn.

The easiest way is to dig from the outside of the clump using a garden fork or sharpened spade. Dig and lift inward toward the centre of the clump; lifting the entire clump or sections at a time. Once the clump is lifted, shake or wash the dirt off the rhizomes and roots. The mature older rhizomes with no leaves attached that have already flowered in years past are often disguarded. But sometimes, if replanted, they will volunteer new shoots that will rejuvenate the old clump.

The most important parts to keep are the healthy, plump and strong new rhizomes that ring the outside of the clump.  If dug directly after flowering, they will probably still have the old flower stem attached. If dug in Autumn they will be the large outer fan(s) of leaves with a brown, flattish potato-like rhizome attached.

Carefully grasp the mature rhizome root and work this back and forth until it breaks away from the parent older rhizome or cut it off where it joins to the parent. Do not grasp the fan of leaves and try to pull the rhizome away from the parent that way as this will often result in the brittle fan of leaves breaking away from the rhizome and ruining its chances of transplanting.

Then before replanting the healthy young fan of leaves with its rhizome attached, trim back the fan of foliage by cutting across the tops of the leaves literally creating a stumpy fan with leaves to 20cm/8inches. Also trim roots by about 1/3 to ½ their length. Now the new Bearded Iris fan is ready to plant. These fans are so hardy while in this state, that they can often be shipped by post without damage. Or they can be placed in a plastic bag with perforation holes or stored in damp peat, sand or soil for easily a week or more without damage. But it is always best to replant them immediately whenever possible!

The best method of replanting Bearded Iris fans is to dig a generous planting hole and then create a small mound of enriched earth in the centre of the hole. The central mound should be as high as or slightly higher than the ground level surrounding the planting hole. This mound should resemble a small volcanic cone inside a larger crater. Place the rhizome in the centre of the hole; resting on top of the small central mound.  Spread out the rhizome roots to dangle down the sides of the mound with the fan pointing outward in the direction where new growth is going to grow. Then back fill the hole. Cover roots with soil and firm this down so the rhizome sits just on the surface. In climates that do not experience severe freezing, leave at least the top ½ of the fleshy upper surface of the rhizome exposed to the air. In severely cold climates just barely cover the rhizome. Rhizomes will rot if deeply covered.

Then water in the newly planted rhizome. When the rhizome is well planted, it will sit exposed above the soil line.  The surrounding soil will gently slope away to maintain proper drainage. Caution! Never allow the rhizome to remain in an indented soil depression that would collect water around the rhizome. This will usually result in root rot and plant collapse.

Bearded Iris grow in a variety of soils from gravel, sand and shale through most average garden soils but prefer medium/heavy loamy soils like pasture land that are very well drained. They tolerate sandy soils with extra compost. Bearded Iris thrive in soils with a pH from 6.0-7.0 preferably 6.8. Alkaline soils or those well-enriched with Lime or Dolomite will still usually grow good strong Iris plants. But add Lime or Dolomite to all acid or volcanic soils with a soil pH below 5.7 to avoid blight and root rots.

Good air circulation and excellent ventilation combined with strong sunshine are essential. They will tolerate partial shade provided that they receive at least 6 hours of direct sunshine each day and their growing position is somewhat drier. But usually flowering and plant health suffer in anything less than full sunshine. Avoid close, humid sites or over-shadowing by other vegetation.

Bearded Irises mostly enjoy open, sunny positions in wide open spaces. One of the fastest ways to kill Bearded Iris is to plant them amongst dense foliage of other annual or perennial plants, shrubs, trees or vines in the cottage garden border or landscape. Bearded Irises demand pride of place and resent any form of over-crowding, even by ephemeral flowering annuals. Once this happens, and the weather becomes cool and damp, the foliage and rhizomes will begin to rot, wither and eventually the entire plant will collapse and be lost. For this reason, do not mulch over their rhizomes. They need air and sunlight on them at all times to keep them healthy and strong.

The only exception to the non-mulching rule is in borderline extremely cold climates that experience deep and prolonged freezing. Under such conditions, the Iris clumps are best surrounded by a hessian screen or covered over with loose evergreen boughs or books of spoil hay or preferably straw or frost cloth. It is much more effective to lean these books of straw into a tepee wedge shape that still allows air circulation around the dormant rhizomes. If ever hay, leafy litter or straw mulch compacts and becomes sodden and wet over the rhizomes, they will be smothered and will rot away.

Feed generously in Early Spring & after flowering. This is when the plants are in active growth and need a lot of nutrients. Use a fertiliser ratio of 6-10-6. They thrive on Superphosphate or Rock Phosphate and/or slow release plant foods with a similar mineral ratio mixed with aged compost & bonemeal. All the vivid blue and purple shades respond well to extra Potassium which brings out their colour. Avoid high Nitrogen fertilisers & especially fresh manures!  Just one application of fresh stable manure around the clumps is usually sufficient to kill them outright!

Once established, Bearded Irises suffer from few pests and diseases. While they do respond to proper care, once clumps become established in a situation to their liking, they can be left alone for decades. Usually if there is going to be a problem it will be due to over-crowding, over-watering or poor drainage.

Bearded Irises look great in large containers or large landscape planters and tubs. The Miniature and Dwarf and even most Intermediate sized Iris are excellent in ceramic pots that provide enough room for their root system and allow excellent drainage without drying out completely. In colder climates where freezing weather could be significant, these pots are moved to a bright, sheltered and very cool spot where they can remain dormant until Spring but where their roots do not freeze.

Bearded Iris in all their forms can create an unforgettably stunning massed bed. But remember that they will all flower out within a few months at the most. So there may be the need for other plantings to provide colour and interest for the rest of the year. Alternatively, Iris works in very well when planted in several clumps along the sunny annual/perennial border provided they are given plenty of space and are not over-crowded by later-flowering species.

Large clumps of Iris create beautiful statements when planted between very open lower-growing, smaller shrubs (especially Roses) and are wonderful rockery garden plants. They are an ideal plant on slopes and terraces as well as in raised beds.

Bearded Irises are highly compatible with almost all Spring-flowering bulbs, Lilies and many other Summer-flowering bulbs as well as lower growing Annuals and Perennials. They look particularly striking when planted amongst Ox-eye and Shasta Daisy mixed with pink Silene armeria (Sweet William Catchfly) and Dianthus barbatus (Sweet William). They are also very effective when planted in large clumps with white Alyssum (Sweet Alice), Eschscholzia californica (California Poppy), Phlox drummondi, and Gazania.

Everyone loves the beauty and glory of the rainbow. And the sweetly fragrant and beautiful Bearded Irises are certainly a Divine living reflection of rainbow flower colours and the exotic glory those living rainbows can create here on Earth.

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