Iris Flowers – 5 Golden Rules
The 5 Golden Rules to Grow Iris Flowers
There are irises that will be in flower at most times of the year, from mid-autumn through the gloom of winter into early spring and then the burst of summer.
Those that brave the inclement weather hug the ground; the rest stand proud. Their scents beguile with plums and primroses and greengages or offend with the smell of raw meat from crushed leaves. The colors of iris flowers are used by watercolorists, the essence of liquid light.
There is an iris flower for every condition, dry or wet, sunny or shaded, arid or fertile. The evergreen leaves that are sometimes variegated are half their charm.
In mythology, the radiant maiden Iris was the swift messenger of the Greek gods whose path was the way of the rainbow. As a genus of plants, however, she is exceptionally diverse. Indeed, there are 300 of them. The Iris Register, begun in 1930 to record all new varieties of iris flowers, currently lists more than 62,000.
For simplicity, however, we need only consider two categories, the rhizomatous and the bulbous. To explore further would tire the concentration and needlessly exhaust the patience. After all, the main difference between the bearded and the beardless is, yes, the presence of or lack of a beard – a small area of hairs on the tongue of the falls, which are the flower petals that droop around the central upstanding standard petals.
Varieties of Iris Flowers
Let us begin at that indecisive cusp of the year as autumn slips warily into the ice of winter when the remnants of an Indian summer arouse with its warmth the small bulbs of Iris histrioides ‘Major’. These varieties of iris will flower even before Christmas, their low Queen Mother blue blooms lasting many weeks.
As they fade, they are replaced by Iris danfordiea with its honey-scented acid yellow flowers.
Vassil, Public domain, via Wikimedia Commons
At the same time, Iris unguilaris, a native of Algeria, will flower, its lilac shaded loveliness smelling of primroses. This eight-inch high iris flower loves to be among grit, the sharper the better. It is most at home against a west or south-facing wall. The iris flowers are an amazing three inches wide. Grit protects it from the slugs attracted to its unopened flower. There is a iris variety, amusingly called ‘Walter Butt’, that is silvery lavender in color.
Spring lengthens its days and the soil murmurs into warmth. The Iris family stir. Iris bucharica, a native of Turkestan, is one of the earliest and easiest of the June irises the English gardener can grow. It dislikes a wet summer, when its bulb may rot, especially on clay-based soils. But, if happy, it will perform with cream white to yellow falls that are sweetly scented.
Late spring and early summer are dog days for the iris family: the time when they most yearn to flower. The bearded, the beardless, and the bulbous all rush into song. Among them, there are those who do best when their rhizomes have been long kissed by the sun and those who hide in boggy soil or who paddle their feet in the water. Some slip into the shade.
In April and May, the crested Iris japonica, which likes a warm and sheltered spot, produces its extraordinary flowers around stiff bamboo-like stems two feet high. They are open flat flowers, iced lilac in color with a lemon yellow flash to each fall. There is a charming variegated one with cream striped leaves, called, Variegata’. Another, ‘Ledger’s Variety’, is virtually identical to the species but hardier.
A shy gem of an iris flower at this late springtime is Iris graminea. Only a foot high, it hides the bushels of its charm within the tight green shafts of its leaves. They are a rich reddish-purple with falls veined blue-purple on white.
We move into early summer and the first of the bulbous iris to flower, the Xiphium family, especially the Iris xiphium. Growing to two and a half feet, this variety of irises is extremely variable and is apt to produce some happy surprises. Indeed, no two flowers are exactly alike. Blue, violet, a touch of carmine, splashes of yellow, cream, and white are her palette. The Spanish iris flowers a fortnight or so later, and even later, in July, the English iris flower will perform.
May and June herald the Iris sibirica with its dark blue-veined flowers that resemble a dancing cloud of exotic butterflies. It is a moisture lover and has a tendency to be thuggish in its spreading habit. In moist or boggy soil in late spring, the natural spreader Iris sibirica will make nearly four feet and bear purple-blue iris flowers that are strongly veined in darker purple.
Also in early summer, the yellow-tinged brownish intrigue of flowers of Iris foetidissima appear, impolitely called the stinking iris flower. In fact, it is not the flower that stinks but the glossy blade-like leaves which, when crushed, give off the whiff of meat, some say roast beef. It is an accommodating plant, thriving in poor soil and shady conditions, as well as in damp. Its seeds astonish through winter as the pods split open to reveal a smile of shiny bright orange fruits which, inexplicably, birds ignore.
There are varieties of iris flowers from America called Pacific Coast Hybrids. Of course, there is no place for snobbery in the English garden. But discernment has its place everywhere, surely? These hybrids are gauntly and jarringly cheerful. That they are ubiquitous is an enigma.
This, then, is the iris family in all its convolutions and intrigue. They are as ladies at the Elizabethan court; enigmatic, disconcerting and, above all, constantly diverting.
Cultivation of Irises
Bearded irises are easy to grow. They are tolerant of exposure (although gardeners with very windy sites may avoid the very tallest varieties of the Iris flowers) and do well near the sea, being very resistant to sea spray damage. They are also tolerant of strong alkalinity and mild acidity. Keep your iris plants free from dead leaves and other debris, and keep weeds and other plants from shading the roots of the iris – bearded irises are very vain, and like to have room to show off!
We recommend that you follow these five golden rules for success with bearded irises:
- Plant in full sun so that the rhizome (woody rootstock) can be warmed and ripened by the sun. The more sun they get, the better they will grow and flower.
- Give good drainage. Bad drainage leads to rot. Add grit to your soil before planting if you are not sure, or use beds raised above surrounding paths so that moisture drains away.
- Shallow planting. The rhizome should be just covered with soil – the top of the rhizome about 1cm (?inch) below the surface. Do not plant with the rhizome exposed – this will not be deep enough for the plant to be properly anchored. The plant will push itself to the surface when it has established new roots.
- Light feeding. NEVER add bulk humus, such as manure. This leads to soft lush growth and few flowers – in extreme cases, it can promote rotting by impairing drainage. Avoid using high nitrogen fertilizers. Instead, use a high phosphate fertilizer at a half rate when planting and in spring to encourage extra flowers.
- Divide clumps regularly. Congested clumps perform badly, flower infrequently, and encourage rot. Lift and divide your clumps at least every third season, this usually being carried out in August or September. Replant only the youngest growth from the outside of the clump, discarding old woody rhizomes from the center of the clump.