The Doddington Method
Described by Antony Jarvis from Doddington as a trouble free way to divide irises, this system has been used successfully in their gardens for the last twenty eight years. He describes the advantages as a regular flowering, combined with speed and physical convenience.

Antony has worked on the premise that irises set their flower initials in August,; this determines how many flowers each stem carries the following year . The traditional method involves disturbing the flowers at the critical point that flowers are being set, and this is borne out by the poor flowering record noted the year after ‘splitting’ takes place. This makes it an attractive alternative and well worth a try.

The Process

Split the irises every year just after they have finished flowering in June
Split the individual plants with a light spade, leaving the part to be retained in the soil. Remove 30-50% of the plant mass. See illustration on where to cut
After splitting, cut back the early summer leaves on the remaining stems, and cut or break the stems at the base
After splitting top dress the plants with bonemeal that is raked in between the plants
When deciding which plants to keep, chose fat, first year shoots, with two shoots carrying the early summer leaves. Chose rhizomes that point in the direction you wish the plant to develop
One further advantage of the system is that the whole process can be done from a standing position, using a light fork and spade, with a pair of shears.. With no replanting of irises involved, the task is far quicker than the traditional method
If you find awkward gaps, irises can be replanted to fill the spaces, and because this is done in June, there is every prospect they will flower the following year
When switching to the Doddington system, it may take a year or two before you reach a steady state.
http://www.englishiriscompany....

Take into account that not all of our bloom seasons are the same. My irises are finished before some other areas start their spring bloom. I always divide and replant in June as my irises finish in May.

I have to plant the new ones that come later from generous iris friends whose gardens do not finish until much later than mine and from vendors who do not ship until late July and into September. A lot of these bloom first year so it sometimes depends on the care they received from the gardens they are coming from.

Unless you want to keep all the increases near each other I doubt I could ever do the whole division process in a standing position. Would be interesting.

Just can't do the plant in June. I purposely have vendors wait to send the rhizomes as planting them in late June through August, when it is very hot and humid, can really stress the plants.

This was from a garden in England. It seems to be a way to keep a steady state garden, as it doesn't say what to do with the 30 - 50 % that you don't keep in the ground. This isn't for every climate, or for new rhizomes, but I thought it was interesting as I am already digging my worst areas.

I can see planting earlier in England as the fall temps get much colder than in my area. And the method would keep the iris clumps in shape.

I understood all of it except cutting back the summer leaves. I think he said to cut them later which is a good thing. Interesting......Some advocate cutting out the mother rhizomes to thin the clump and therefore leave the remaining ones in place. That would not interrupt the bloom cycle. And you can do that with a knife and not have to dig the clump up.

We cut back Siberian leaves in Oct. otherwise they are a mess in spring. We don't cut bearded leaves, although will pull off dead ones.

janielouy said:I understood all of it except cutting back the summer leaves. I think he said to cut them later which is a good thing. Interesting......Some advocate cutting out the mother rhizomes to thin the clump and therefore leave the remaining ones in place. That would not interrupt the bloom cycle. And you can do that with a knife and not have to dig the clump up.

Janielou, tell me more specifically how to do that , if you know, please .

I usually don't cut the leaves back, however on some years I have in some beds and for different reasons. If I have a really bad year with leaf spot or a lot of dead leaves I may. I also have done it to help determine which rhizomes belong to which cultivar if some have grown close. It's easier to see which clump they belong to when you do that. I also noticed that this year I have very little leaf spot for some reason. I sure have never done anything to stop it chemically but just don't have much of it at all. Other years it is all over the place. Go figure????

tveguy3 said:I usually don't cut the leaves back, however on some years I have in some beds and for different reasons. If I have a really bad year with leaf spot or a lot of dead leaves I may. I also have done it to help determine which rhizomes belong to which cultivar if some have grown close. It's easier to see which clump they belong to when you do that. I also noticed that this year I have very little leaf spot for some reason. I sure have never done anything to stop it chemically but just don't have much of it at all. Other years it is all over the place. Go figure????

Do you make multiple clumps in various locations of the same variety as you divide or keep each variety together?

Most of the time I keep each cultivar in one area, however for those that I want to use for crossing more often, I sometimes have a clump near the house where they will bloom earlier, and another clump out where they will bloom later. That gives me a longer time to use them.