I first came across irises when I got my first allotment garden at Stirling Park on the side of Dundee’s Law Hill. There was a beautiful row of blue coloured English iris well established along the main garden path. To add to the show I had bought some Dutch iris bulbs though these flowered after the English iris. Later in 1969 while studying at Essex Institute of Agriculture in Chelmsford we got involved in breeding flowers of the large and very colourful bearded iris. I got hooked and now iris is on my must have plant list.
Iris comes in a range of types and sizes. The most popular are the tall bearded iris, Iris germanica, also known as flag iris with thousands of different varieties available most of which are scented. They are always available in garden centres, though there are several specialists where you can get the very best varieties but usually at a higher price. These iris grow from rhizomes and are best planted in autumn. They like to be in the sun in fertile soil that is well drained and either neutral to slightly alkaline in pH. When planting keep the rhizomes on the soil surface as they will rot if planted deep.
Established clumps will need splitting up and replanting every three years or so.
English and Dutch Iris
The English and Dutch iris grows from bulbs, usually planted about six inches deep in autumn. The yellow, white, purple and blue flowers open in summer growing up to two feet tall. The English types are very hardy and can be left to form large clumps over several years before they need lifting and replanting. However the Dutch iris are best treated like a tulip by planting them in autumn, then lifting them in summer after the leaves have died down. They can be stored in a cool shaded place.
Bog and pond garden iris
Although most iris prefer drier soil and a warm sunny sheltered spot there is even an iris for the less sunny and more moist garden. Iris sibirica prefers a more permanently moist soil associated with pond fringes, but do not plant it in very wet soil otherwise it will rot.
Iris sibirica flowers in summer with blue, purple and white flowers up to 2.5 feet tall.
Rock garden iris
The rock garden is also well catered for with a range of dwarf irises most of which flower in late February to March. These all prefer a well drained soil in full sun and it is important that the ground is very well drained in winter. It is a good idea to incorporate grit as well as some well rotted garden compost into the soil before planting. Iris reticulata and iris histrioides grows about six inches tall with blue flowers. Iris danfordiae grows the same size but has yellow flowers.
Plant of the week
Kaffir Lily (Schizostylus coccinea) is also related to the iris family. It is a semi evergreen herbaceous perennial growing in clumps about 24 inches tall with white, pink and red flowers in late autumn and early winter. It prefers moist but well drained fertile soil and a warm sheltered aspect in full sun. It is fairly hardy in most winters.