there is a rather active iris forum... for the real experts ...

i tend to only dig them up.. after the iris borers destroys the clump ... some of my untouched clumps are going to 7 years or so ... i am sure there are others who do it much differently ... BTW.. do you need more around the yard ???

primrose.. never got any to winter over ... so i dont know...

ken

The only primrose I grow other than my No ID one is Primula veris and I must admit I don't divide it very often - maybe every 4 years or when I get around to it. It probably could be divided more often, but for some reason I don't like the chore. The divisions always look so crappy that first season, but they do survive.

Kevin

Just had a thought. I wonder if you mean Primula or those other things that go by the common name 'Primrose'?

This post was edited by aachenelf on Thu, May 22, 14 at 18:57

Are you referring to bearded iris, Siberian iris or Japanese iris? Siberian iris tends to form a clump rather quickly that's difficult to divide/cut through the base/root mass. I have a number of SI clumps in various beds, all but one grown from seed via winter sowing. All are healthy and bloom each year to my delight. I haven't felt compelled to divide any thus far.

Bearded iris is slower growing/multiplying than SI but still a delightful addition when blooming. Japanese iris performs well despite being planted in less than ideal growing conditions.

Primroses are not great performers in my garden other than two that have held on for the past 3 years.

First answer......bearded iris. I have a number of clumps around my gardens, and got to thinking that maybe I should divide or split them, as they have been in the same place for 5 years or more. I don't get borers up here.

Second answer, Primula....I have one plant, planted on a whim I don't know how many years ago.....at least 5 maybe 10. It comes back every years and blooms, but I am thinking maybe I should be doing more with it than just enjoying it! Yes I would like more!

I divide bearded iris when the clumps get crowded/are taking over neighboring perennials. Mine grow at a good clip - they are happy where they are growing. I divide in mid to late summer. Very easy to do, just dig and separate the rhizomes, replant at a shallow depth - I usually leave a bit of rhizome above the surface. I normally don't have problems with borer but have in some years; if I notice tunnels on the leaves mid-summer I cut the leaves back to the point where the tunneling stops - have to leave some green to feed the rhizomes. No, it isn't pretty, but I have the iris in a spot where other plants hide the foliage to a large degree.