Best of the Bunch Iris reticulata and friends.
Given any reasonable well-drained soil in a sunny position, these bulbs will go on to produce spectacular displays of flowers, with the clumps increasing year on year. A high potash feed towards the end of the flowering period will help to restore the bulbs after the efforts of flower production and you can lift and divide the clumps of bulbs to spread them further around the garden in late summer, or even give a few to friends and neighbours - who knows what you might get back in return!
There are a number of good species to look out for and some garden centres and nurseries are selling potted ones now for you to put straight out in the garden. If you miss out it is not too long to wait until late August when the dry bulbs reappear. Look out for the brilliant yellow Iris danfordiae from Turkey, the deep blue I. histrioides, also from Turkey and the violet and purple Iris reticulata from Iraq and Iran to add to your spring display. All of these can work in containers, in sunny borders and in rockeries and gravel gardens.