Ina, As long as you are planting them in well-drained soil in a north-facing spot (would be south-facing in the Northern Hemisphere), they will persist for many years even with winter rainfall. In this Berkeley planting strip they come back year-upon-year: http://flickr.com/photos/xerantheum/… just as I believe they do at the UC Berkeley Botanical Garden. Jacob On 23 July 2012 00:46, Peter Taggart <petersirises@gmail.com> wrote: > I must apologise Ina, > Thank you for your correction Dylan. > It is I who is in error on this this time, I am not so familiar with the > rootstock of Tigridia. > Looking them up, I see Brian Mathew puts them down as bulbs along with > Trimezia described by him as bulbous/rhizomatous, and Herbertia described > as bulbous. > I shall look more closely at the rootstock of Tigridia when they are > available in the spring here ! > > However the rule of thumb given is not so good unless Irids excludes the > genus Iris as there are many old world Iris which are true bulbs, Iris > xiphium is a true bulb! Iris reticulata is too, and Iris serotina, > lusitanica, latifolia, Iris magnifica, aucheri, planifolia, palaestina, > histroides ....... I grow many bulbous Iris from the old world, as well as > many rhizomatous ones. Romuleas, Gladiolus, Crocus, Moreas (Gynandriris) > do have corms and occur in the old world too. > Peter (UK) > > On Mon, Jul 23, 2012 at 5:24 AM, Hannon <othonna@gmail.com> wrote: > > > Tigridia species have true bulbs rather than corms. I believe this is > true > > for all New World irids with "bulb-like" rootstocks. Corms are the rule > in > > Old World genera. > > > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/ >