We specialize in seeds from several sections of the genus Iris, the large type-genus of the Iridaceae with about 250 species spread around the northern hemisphere. One group for which we have a long-standing affection and an association extending over almost 40 years are the rhizomatous irises of Sections Oncocyclus and Regelia, known to enthusiasts as ‘the arils’ because of the large white aril on their seeds. These irises belong to Subgenus Iris, the bearded irises, but their cultivation is very much more of a challenge than it is with their close allies in Section Iris. They are the most spectacularly beautiful of all irises, indeed of all plants, and one of the most difficult groups to grow well, especially in the wet climate of western Europe. We grow a wide range of species belonging to these sections under glass to make available hand-pollinated seed from correctly named plants of known wild origin and we collaborate with other European growers such as Michael Kammerlander, Chris Lovell, Ed Picken, Norman Stevens and Bob and Rannveig Wallis to conserve these difficult species in cultivation.

The Mediterranean oncocyclus irises are mostly larger growing, robust plants, distributed from northern Syria, through the Lebanon to Israel and Palestine. They start to grow in autumn with the first moisture and their foliage may not tolerate very low temperatures in winter. Some are quite vigorous plants and include some of the easier species to grow.

The desert oncocyclus irises extend from the Syrian Desert southward through Syria, Jordan and southern Israel to Sinai in Egypt. They include several attractive dwarf species but they are used to a dry atmosphere throughout the year and have their main growing period in winter. They are the most difficult to cultivate in wetter and colder northern climates, where light intensity and temperatures in winter are likely to be too low and atmospheric humidity too high.

The steppe oncocyclus irises are distributed through the steppes of Central Anatolia, Transcaucasia and northern Iran, from near Aksaray in western central Turkey to the Kopet Dag range on the border between Iran and Turkmenistan. They are used to severe continental climates, where they are covered with snow for several months and the summers are dry, though not always extremely hot. Their main growing period is in spring, when the ground is moist from snow-melt, but root activity underground starts with the first moisture in autumn and proceeds slowly at the low winter temperatures. These are almost all dwarf plants with narrow foliage and are perhaps the easiest to grow under glass in Britain. They are temperature-hardy plants which could be attempted in a well-drained, gravelly bed in the open garden in the higher, drier, colder parts of North America, such as northern Arizona and New Mexico, Colorado and the Great Basin area.

The regelia irises extend the distribution of the arils eastwards into Central Asia. This is a small section of the genus comprising about 5 or so species. Most are more easily cultivated than those in the Section Oncocyclus and are good plants to start with if you are interested in growing the arils. We grow several planted out along with Eremurus and other Central Asian genera in our netting-sided polytunnel. In such a situation they are very trouble-free. They can even succeed in a raised bed in the open-garden in the drier parts of Britain and will offer no problems outside in colder drier areas elsewhere in Europe and North America.

Propagation from seed is the best method of maintaining all these irises in cultivation. Seedlings will be free from virus and more vigorous than divided rhizomes. Once you are producing seeds yourself, you can sow green seeds extracted from the pods before they split but we cannot arrange to send this out. Even fresh, dried seed can take a long time to germinate. Ken Bastow, an expert cultivator of these irises claimed that 5-6 year old seed gave the best percentage of seedlings most promptly but we have been told that most growers have had some germination from the current year’s seed, which we send out, the first season. Never discard ungerminated seed. It is large enough to check if it is still sound. If so, it will come up in time. Most breeders of hybrids use the complicated process of embryo-culture as a short-cut but this can be risky and it requires some experience and skill. We prefer conventional methods and patience. As with other summer-dormant steppe-species, sow from summer to early winter, place the container outside and remove them to a more protected environment when the first sign of germination occurs in spring. If sown early enough or in a previous year, seed may germinate in autumn with the drop in temperature, so do not ignore seed-containers until spring.

Nomenclature : The Turkish and Iranian species are covered by ‘Flora of Turkey’ and ‘Flora Iranica’. The treatment by Per Wendelbo and Brian Mathew in these floras tends towards ‘lumping’ several taxa into one broad species. In contrast to this approach, the attitude to the species outside these areas has been one of extreme ‘splitting’ where every minor variant has been given specific status. This is the reason we have not indicated the number of species in this section. It is a very debatable matter. ‘Splitting’ makes more fun for the gardener who wishes to acquire representatives from every colony. We try to even out the nomenclature by not following the Wendelbo and Mathew nomenclature too slavishly.

Further information : 'The Iris' by Brian Mathew (1981) is the best, easily accessible source of information. There are plenty other books of varying quality on irises but the information on the arils in these is not always reliable. There is an award-winning overview of Section Oncocyclus written by Jim Archibald and published in The Quarterly Bulletin of the Alpine Garden Society, Vol.67, No.3 (September, 1999). This was reprinted in a subsequent Year Book of the Aril Society International.

Enter 'oncocyclus' or 'regelia' in the 'description' field of 'search' to access a complete list of all the members of these sections listed in alphabetical order