Iris

09. May 2021 by Isabelle Van Groeningen
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Iris sibirica 'Strandperle' © Isabelle Van Groeningen

Flagge Deutschland für deutsche Übersetzung auf Deutsch lesen – Although the Narcissus are still flowering, and the tulip season is only just coming into full swing, I did spot the first bearded irises flowering already.

They are not the first to flower though. The delicate Iris unguicularis,* a drought-tolerant Algerian Iris has survived the last winters well, planted at the foot of a south-facing wall in a very sheltered position. During the summer months, she is shaded by plants standing on the terrace, which does not seem to bother her at all. The small spring-flowering irises such as the yellow Iris danfordiae (Gelbe Zwerg Iris) and the various I. reticulata** (Netzblatt Iris) such as ‘Harmony’ and ‘J.S. Dijt’ are also long-finished. These bulbous types are best bought in the autumn as bulbs, and planted in pots, rockeries, or drier meadows with good drainage.

It is a large genus of nearly 300 different species and hundreds of cultivars, with very distinctive types, suited to a wide range of environments. Some like to grow in or near the water such as the yellow flag Iris Iris pseudacorus (Sumpfschwerdtlilie) and the Japanese Iris (Iris ensata), in moist meadows (Iris sibirica) whilst others such as Iris barbata, the Bearded Iris*** are adapted to grow in sunny, dry conditions. In strong contrast Iris foetidissima will grow in dry shady places. Because the Bearded Iris is so glamorous and attractive it tends to steal the show. But quite a few others deserve attention.  

Iris barbata naturalised in southern France © Isabelle Van Groeningen
Iris barbata naturalised in southern France

There are two easy-to-grow Irises I find particularly useful for the garden. Not that the bearded ones are fussy, but their appearance on the flowering stage comes with great diva-like drama, whilst the Siberian Iris is a reliable, decorative garden guest. Iris foetidissima is  probably one of the least known species, but is valuable as it will grow where few other plants like to be: in shady, often dry woodland margins.   

Iris sibirica

The grass-like narrow leaves of the Siberian Iris, can reach up to 80cm. Above these the mostly branched flowerstems can grow up to 1,20cm tall, depending on the variety. This is an elegant slender, upright perennial that looks good in an early summer-flowering border or in a flower meadow. It has a wide distribution from much of central Europe, across to central Asia and Siberia, growing in moist meadows.  I am very fond of these plants, as they provide a long-lasting point of interest. The flowerbuds are enclosed in reddish papery spathes, that are attractive. After flowering most cultivars will set seed and produce a ca. 4cm long upright seedpod. These will dry and remain on the pant until you remove them at the end of winter and the new growth starts to show. These hollow capsules are ideal insect refuges for the winter months. There are numerous cultivars on the market, ranging from dark violet, to pale blue, white and yellow. ‘Caesar’s Brother’ is a favourite, as is ‘Cambridge Skies’.

The rhizomes will develop a tight rootball, that occasionally needs to be lifted and divided, as otherwise the plant develops a dead centre.  

Iris sibirica must be divided every 5-6 years © Isabelle Van Groeningen
Iris sibirica must be divided every 5-6 years

Iris foetidissima

iris foetidissima 'Citrina' © Isabelle Van Groeningen
iris foetidissima ‘Citrina’

The Stinking Gladdon is a European native with broad, mostly evergeen leaves reaching about 60cm in height. The flowers appear in early summer and are easily overlooked. They are a rather pale mauve and cream colour. The form much more attractive form ‘Citrina’ is sulphur yellow. Why do I think this is a valuable plant when the flowers pass unnoticed? Because from late summer onwards you suddenly stop in your tracks, as the large seedpods burst open to reveal bright orange-red glossy seeds that are very decorative. This splash of colour in dry shady areas, where at that time of year everything is just tired and dry, is a real treat and is a great companion to Lords and Ladies (Arum maculatum) whose orange seeds are equally attractive in the late season. Both provide great foliage that contrasts well with ferns during the cold season, and will cope well with dry, shady conditions.  

Iris ensata

The Japanese Iris is another species that forms a dense clump of rhizomes, out of which about 80-100cm tall narrow green leaves arise. It originates from the east and has been cultivated since at least 5 centuries in Japanese gardens in associated with rice paddy fields. They were introduced in the West in the mid-19th century. They prefer an acidic soil, and need moisture during the summer months, but do not mind being drier in winter.  

At first glance, the plants appear quite like Iris sibirica. Whereas the flowers of the Siberian Iris tend to be slender and upright, those of the Japanese Iris are more horizontal in silhouette, spreading its arms wide.

It is impossible to mention them all – I would be writing a book rather than just a blog. The asterisks refer to previous articles where you can explore this fascinating genus a little more. For serious enthusiasts, there are real collectors items, such as the Juno-irises which are very beautiful, but very difficult to grow. Many of the species require such a dry resting period during summer, that they are kept under glass to keep the rain off and maximise the effect of the north-European sun. But whatever their growing requirements, and how easy or difficult they are to grow, they all share the similar beautiful flower structure with the distinctive three upwardly growing petals know as Standards and three “falls” that point downward. They can be larger, wider, narrower. They are all called Iris, derived from the Greek word for rainbow. Their huge colour range certainly represents that.

Iris pseudacorus © Isabelle Van Groeningen
Iris pseudacorus

Read more:

*Winterblühende Schwertlilie – (Winter flowering Iris) 19. Januar 2020

**Über Iris ‘Katherine Hodgkin‘ und Alpine Häuser (About Iris ‘Katherine Hodgkin‘ and Alpine Houses) – 19. Januar 2019

***Bart-Iris – (Bearded Iris) 25. Mai 2019

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