How to grow irises in France: planting and care guide

There is perhaps no other flower in the garden which comes in such an enormous range of colours as the iris. In Ancient Greek mythology, Iris, daughter of Electra and Thaumas, was the personification of the rainbow. She encompassed all the colours of the spectrum, and iris flowers can be anything from pure white to deepest black, with everything in between. 

There are some 310 accepted species and irises on almost every continent (Antarctica excepted). Irises can be tiny, piercing the snow in your late winter garden or rising a stately metre or more by a summer pond. There are irises for all seasons and an iris for most situations.

Irises are often found in French art: from medieval heraldry and tapestries (the fleur de lis is an iris, not a lily), through the Impressionists – Monet, Bonnard and, especially, van Gogh – to Art Nouveau when the iris’s stylised form decorated buildings, furniture, interiors and jewellery. 

The shape of the flower is distinctive: there are six petals on each. The bottom three are called the falls; the central one is like a wide tongue. The three upright petals are called the standards. In the throat of some irises is a row of fuzzy hairs called the beard – they look a bit like a caterpillar has crawled onto the flower. The size of each flower can be 4cm up to 18cm depending on the type of iris you grow.

Best time for replanting

I find September is a good time for planting or replanting flag irises. Flag irises grow from a big fat rhizome, buff-coloured and looking somewhat like root ginger. If you visit gardens which have good iris collections (or specialist nurseries called iriseraies), you will see the rhizomes sitting mostly on top of the soil in a sunny position. 

This type of iris needs hot, dryish conditions. The rhizomes seem to thrive in conditions many other plants would find challenging. On baked Gascon clay, they flourish and multiply so that, by the end of some summers, something must be done to stop the congestion which would affect next year’s flowers. 

After the weather cools a little and there has been some rain to soften the ground, I get in with my broken three-pronged fork. It’s narrower so helps get between the rhizomes. I carefully lift all the rhizomes in a particular area, standing them on a tarpaulin. Then I fork in some garden compost, rake it level and pick the fattest and best rhizomes to replant. I cut the flat, sword-like leaves down to about 15cm and then line up the selected rhizomes, pressing them onto the surface of the lightly firmed soil about a hand’s width apart. Water well. Use any leftover rhizomes in other parts or put them on soil in seed trays, in a cold frame to swap with someone next spring.

In our garden I have had some fabulous flag irises from someone who comes to the Troc’Plantes (plant swap) at the Jardin Partagé in Marciac. Over the years I was given chrome brown, eggy yellow, red and all shades of blues and purple. My husband fell for the intense black at the Fourcès two-day floralies (flower markets), and my sister-in-law sent me supermarket pink “Frilly Knickers” with blooms like a can-can dancer’s drawers.

After all the flag irises have been tucked up in their newly remade beds, I start looking for iris bulbs for spring. Flat terracotta bowls of tightly planted Iris reticulata can be moved around to bring spots of jewel-like colour to a late winter garden. “Katharine Hodgkin” is a famous and widely available bulb but, in my garden at least, I have found its colour to be somewhat washed out. I prefer the intensity of “Blue Dwarf”, “Blue Note”, “George” (rich papal purple), “Sunshine” (vivid yellow) or pure white with a yellow ‘tongue’, “White Caucasus”. 

A new arrival

Planting drifts of iris under trees is very effective – there’s a property on the way to our local market town where the autumnal carpet of pink cyclamen alongside the tree-lined drive gives way to bright blue irises in February. It is magical.

I will also look for bulbs of Dutch iris which come into flower at the same time as the first tulips. They’re planted ‘lasagne-style’ in the large terrace pots with hellebores, blue primroses and violas above them. The following year they are planted in the bed along our drive when they stand above the wallflowers. My favourites are the deep blue and yellow, but as they mostly come from a discount supermarket there is a range of colours.

By the pond I have both Iris pseudacorus, the yellow flag iris which arrived on its own and has its roots just into the water, and Iris sibirica, a tall, slender perennial with deep purple flowers. They thrive in the opposite conditions to the flag iris. I have two other sorts of iris which came from a different swap: Japanese iris and Algerian iris. Both are happy in partial shade and both have large floppy flowers. The former likes to be damp and flowers in early to midsummer and the latter blooms around April.

The final iris in our garden is a Griffle – a rescued Petit Griffon Beagle cross who, when she arrived at eight weeks old, had a face like an iris. Now at six years old she spreads herself around the garden with gay abandon.