Monday 22 January 2018

Beautiful Pacific Coast iris thrives in adversity

THERE is a group of irises, known as Pacific Coast irises, that are exceptionally beautiful, in flower at the moment. They are much smaller than the familiar tall, border irises but the flowers are nearly as big. They are very easy to grow and remarkably durable and long-lasting plants.

These irises are found growing in a matrix of grasses and other low-growing plants in the coastal prairie of the west coast of the United States, a relatively narrow strip influenced by the ocean. The hills on which they grow are dry but the plants are supplied with moisture by mist and fog that drifts inland.

A cold current runs down the coast and when warm air off the land meets the cold air from the sea, moisture condenses into fine droplets. To trap the droplets of water, it is a big advantage to have fine grassy foliage and these irises are equipped with narrow, green, grassy, evergreen leaves.

Being evergreen allows them to trap moisture year-round and, in a garden, it is also useful because they have a presence all through the year. The conditions in which these irises grow are remarkably tough but this makes them excellent garden plants, well able to cope with aggressive neighbouring plants.

The iris flowers are about 10cm across, relatively large for a small plant. Each flower stem carries several flowers that open in succession to keep them flowering for up to three weeks, making a low mound of colour. There are several related species. Iris douglasiana has cream to red-purple flowers. Iris tenax can be creamy yellow to almost purple but it is most often seen in a nice deep blue. Iris innominata also varies from yellow to blue and purple.

When the creamy yellow kinds were crossed with blue and purple sorts, a range of toffee brown, coppery brown and pale ochre colours was created. The species hybridise easily and named hybrids have been raised. The different species tend to occupy a defined geographical area of the coastal range. These clump-making irises could be used in areas of dry soil, semi-wild at the edges of a garden in company with grass. They can also be grown at the front of beds and borders where they will form a neat group, slowly spreading the clump outwards.

Even though the clump spreads, it does so slowly and does not need regular lifting and division. They can be easily divided to make new plants. These species are native to sunny conditions and do not tolerate shade very well. Full sunshine will increase flowering.

Sunday Independent

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