Sometimes known as the Algerian iris (ht 50 cm), this is a Mediterranean rhizome that grows reasonably well in Sydney, though it thrives much better in inland NSW where the winters are colder and the summers drier (as illustrated in the second photo, below). Its main appeal is that is blooms in winter, the scented flowers appearing amidst the reedy, arching foliage. The buds are like tight scrolls, which unfurl to reveal the pretty flowers - which are mauve-blue in the species, but can be white, rich purple, silvery lavender, pink or darker blue in some of the cultivars. It grows best in a dry, sunny and well-drained position. Dry soil seems to be particularly important in summertime, and they seem to prefer alkaline conditions.
Some gardeners cut the foliage low in autumn so that the flowers (which have short stems) will be better displayed; often the leaves become very scruffy over summer so this does tidy the plant up. The plant will eventually form thick clumps, which should be divided (in autumn) only if they become hopelessly congested, as they prefer to be left alone. Snails may attack the flowers, so should be watched out for. The plant associates well with other dry-climate, Mediterranean plants, including lavender, rosemary, Artemisia species and wallflowers, as long as they are not overshadowed by these taller plants. The flowers can be picked for vases indoors, just as they start to open.