Plant of The Month – Iris Unguicularis
Iris have never been my favourite plants as I find their flowering season too short and the rest of the year their foliage can often look a little tatty and let down the rest of the scheme. However, there is one Iris that I think is worthy of a place in your borders and that would be Iris Unguicularis. This tough little plant seems to thrive on neglect, really awful soil and often comes as such as surprise as it flowers in the depths of winter.
Iris Unguicularis (formerly I. stylosa) has always been known as the Algerian iris, although it is found in Greece and its islands, as well as north Africa. It is one of those plants usually ignored until buds appear, sometimes as early as Christmas. Flowers are produced on and off over the next few months, often as late as Easter. They are lavender blue, with delicate markings, and sweetly scented. The erratic flower production is actually a clever ploy to avoid weather damage – although the buds are frost-proof, the flowers are not.
The clumps of foliage tend to hang on to their dead leaves, which gives them their unkempt look. Generally, the leaves grow about 12 to 15in, with the flowers nestling among them. The variety ‘Mary Barnard’ is tidier than most as the leaves are shorter. Other good ones include ‘Abington Purple’ and the pale, free-flowering and heavily scented ‘Walter Butt’.
Iris Unguicularis grows naturally in shaded rocky habitats. In British gardens it needs full sun and a dry, stony alkaline soil. Not surprisingly, rubble-filled soil at the base of south-facing walls is usually where it does best. There is another factor in success, patience. They don’t establish or flower quickly and don’t expect them too either– the older the clump the better the flowers. Young plants, especially if grown from divisions, do need watering during their first summer but after that they are best ignored.
Iris unguicularis tends to flower in splendid isolation as there is little else on top form at this time of year in the location in which it thrives. However, its ideal garden habitat is distinctly Mediterranean and therefore perfect for combining with low-growing and drought-tolerant shrubs such as lavenders, cistus and santolina – all of which have grey foliage which is a good complement to the iris flowers. However, if grown in close quarters, it is important that you ensure the often sprawling tendencies of these shrubs do not overwhelm or shade the iris foliage. This little iris will be sure to bring a little bit of light in the depths of the cold dark winter.