A surprising number of enthusiastic gardeners have requested information on the cultivation of those glorious flowers known as bearded iris. So this week’s column is dedicated to the cultivation of these stunning rhizomatous beauties which deserve to be far more widely cultivated in Pakistan than they are at present.
Iris is a genus of approximately 300 different species of flowering plants which, due to the many wonderful colours of the families’ gorgeous blooms, takes its name from the Greek word for rainbow (Iris). These long-lived perennials are either rhizomatous, as is the bearded iris, or bulbous, such as the popular Dutch iris, in form.
Predominantly spring flowering — although some strains of bearded iris, referred to as ‘remontant’, have a second flush of flowers later on in the spring, or in some cases autumn, season.
Originating from the Middle East, bearded iris requires plenty of sunshine and excellent drainage as, if grown in water retentive or overly wet soil, various forms of rot and rust can, potentially, be lethal.
Plant bearded iris and have a riot of rainbow colours in your garden
I fell in love with bearded iris many moons ago and slowly built up an extensive collection of these stately plants — although medium tall ones were included as clumps of eye-catching, late spring colour, in massed plantings on sunny banks throughout the garden — which enjoy the blazing sunshine, the heat magnified by the natural stone retaining wall that shelters them from the wind. With colours ranging from the deepest amethyst, sky blue and bright lemon through to purple and yellow bi-coloured specimens, bearded iris are the backbone of the garden orchard which would be rather bland without them as, when not in bloom, their massive clumps of spear-shaped leaves add architectural interest and form too.
|Blue-beard, Photos by the writer|
Each and every individual flower is composed of six ‘parts’: three standards or upward standing petals and three falls, these are the downward flowing petals with a central line of raised hairs referred to as ‘beards’. These beards, often dusted with golden pollen, provide an inescapable magnet to bees which, without hesitation, clamber up right into the iris ‘throat’ where, especially on sunny days, they drowse in satisfied slumber.
The main problem, as asked about by readers, is that of rotting away of the rhizomatous tubers which, on the whole, is a relatively simple matter to overcome: a mistake made by many is to plant the tubers too deep. The tubers of Bearded iris need exposure to sunlight, thus, should be planted on the soil surface with just their bottom one third to one half, pressed down into the soil. Covering the tubers completely, irrespective of soil type, causes them to rot away, quite rapidly, into nothing more than black sludge. Incorrectly planted tubers tend to begin rotting in just one section, with the rot quickly spreading throughout the rhizome. Affected tubers, if caught soon enough, can be cut into large pieces, and these ‘clean’ pieces can be immediately replanted elsewhere and allowed to grow on. Depending on the size of the ‘salvaged’ pieces, they may not flower for a year or two but the wait is worth the end result. Rot infected tubers can also be lightly dusted with pure sulphur powder to help prevent rot but this method will not work unless soil and drainage conditions are suitable.
As already mentioned, rhizomatous iris must be grown in well drained soil and in a very sunny location. A soil which has a negative pH value, neither acidic nor alkaline, meets their requirements perfectly. Avoid adding too much nitrogen at any stage as, whilst this encourages lots of leaf growth it discourages flowering and, in extreme cases, encourages the plants to completely outgrow their strength. The resultant mass of huge leaves eventually yellow, distort and die off. A generous amount of river sand — not saltish sea-sand — mixed into the soil can assist essential drainage which is further improved if the plants are cultivated in raised beds. Growing them, individually, in very large clay pots, is another way of maintaining necessary cultivation and drainage conditions.
Bearded iris are increased by division of overcrowded rhizomes every three to five years depending on their vigour. This division should be done after they have finished flowering and after their main leaves have been allowed, naturally, to die back. Cutting back healthy green leaves is not a good idea as, during the dying back process, all leaf nutrients are reabsorbed into the rhizomes to keep them healthy and strong.
These gorgeous plants will not take being over-watered but will (this is great) endure fairly long periods of drought without any harm whatsoever.
There are literally hundreds of hybrid Bearded iris to be tracked now and they are, as their name implies, found in all the colours of the rainbow, plus, in single and double forms with, as an added bonus, some of these being fragrant.
If you haven’t already done so, give these stunning beauties a chance and, I’m sure, you will be absolutely delighted with the result.
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Published in Dawn, Sunday Magazine, July 20th, 2014