Cultivating Iris
There are over 200 known species of Iris, divided as follows:
While we have some examples of most of the above types, Iris Australis concentrates on Bearded Iris, primarily Talls (TB). We currently have almost 1100 different tall bearded cultivars, from all over the world. Not all 1100 are available to purchase (yet).
In 2020 we also hope to bloom several hundred new MTBs (Miniature Tall Beardeds) imported as seed from Lynda Miller, a premium MTB grower in Oregon, USA. We will also be growing TB seed imported from Anton Mego, an elite grower (and good friend) in Slovakia.
Bearded Iris grow best in full sun (minimum six hours per day), and are tolerant of a wide range of soils. They need warmth in summer, and cool in winter to bloom at their best. Rhizomes are best planted with about a centimetre of soil over the rhizome, but no more. The rhizomes need to “bake but not burn” through summer to ensure good bloom the following Spring.
Dwarves bloom before Medians, followed by the Talls. Talls tend to be divided in to early, mid-season and late. With sensible planting and management, six to eight weeks of bloom can be expected. Some TBs rebloom in Autumn.
A good modern iris should have 6-12 blooms per stem, spread over 3-4 bloom positions (sockets). The top (primary) socket should have 2-3 blooms in it which should open sequentially, giving 6-10 of blooming from just the one position. The 3-4 lower sockets and branches will have 1-2 blooms per socket.
Each rhizome only blooms once, but after blooming it sends up increase (babies) which should bloom the following year. Depending on how rapid the increase, the clumps are best dug each 3-5 years, the old dead rhizomes removed and the newer ones broken up and replanted.
Rhizomes are best planted in early summer for areas with summer rainfall, or late summer/early autumn in areas with autumn-winter rain. In Bilpin, I try to dig and divide in November-January.Iris need minimal water, once established. In the Blue Mountains, I barely water, if at all, other than new baby seedlings and iris that have just been transplanted.
Fertiliser needs depend on your base soil. If fertilising, ensure that your fertiliser of choice is not too high in nitrogen or you’ll get glorious leaves, but less blooms. Superphosphate is recommended as it’s high in phosphorous.