best time for dividing them in Britain is Automn. There is a short time when they grow new roots and there is not a lot of reserve in the thin rhizomes. You could try now but keep the pieces as big as you can, and dont let them get hot or dry unless you are sure that they have rooted. I find that half rotted garden compost is good for potting them. It might be easier to let the grass grow and wet the grass with a glyphosate mix using a latex glove, but in growth the Iris will be very sensitive to the glyphosate too. The Iris rhizomes root best plunged deep in damp airated compost with plenty of nutrients. Iris douglasiana is the most forgiving PC iris that I have grown Peter (UK) On Sun, Feb 3, 2013 at 7:35 PM, Gastil <marygastil@yahoo.com> wrote: > hi Kathleen and other PCI growers, > My only experience with these is to buy them in a gallon pot from our > botanic garden, plant them, and then do absolutely no maintenance > whatsoever for 2 decades. They multiply and bloom all on their own. I do > not cut-back, water or dead-head them and I seldom weed them. One clump is > now invaded with Bermuda grass which is difficult to eradicate so I have to > dig it up to get those grass rhizomes out. The only times I have tried to > transplant these kind of iris they all promptly died. So, my question is: > which season is best to dig these up? Right now they have small new shoots > emerging. > > I vaguely remember mine might be I. douglasiana or a cultivar or hybrid of > those. It is the white blooming clump which I have to dig up. They are > definitely Pacific Coast Irises. > > - Gastil > Santa Barbara, California (on the Pacific Coast) > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/ >