Digging up/separating iris

jclepine(8b)May 7, 2009

So, while on dog-doody patrol, I noticed tons of iris rhizomes floating around on top near the irises. Ew, they almost looked like something I should throw away or like soggy cactus paddles!

But, I could figure out that they belonged to the irises that were here when we got here and that I've ignored for so long. I'm guessing that the area was so crowded that they popped out of the ground and then rotted away under the snow.

I don't know how to dig up and separate irises!! I'm sure there is nothing to it, but I think it best to ask first.

If I were to go out there and do this now, I'd probably take my weed popper (just the little flat and narrow metal stick with a handle) and pry a few up so as to allow room for the ones I leave in the ground.

Is that good enough? Do I have to dig them all up and then replace some in an organized way? Is this a good or bad time to do this? The foliage is only about two inches out of the ground so far.

I tried to look this up since I'm sure it has been posted before, but the search results here are kind of hard to wade through and I didn't see anything I was looking for.



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If these are the common, tough 'bearded Iris' then it is generally believed that the best time to dig them is in late summer. Seems like an odd time but that's what I've read time and again. It's best to get a spading fork under them and lift so hopefully you don't break off too many of the roots emanating from the rhizome. Then you shake off the excess dirt, and generally try to cut off the outer part of a rhizome clump to replant, on the basis that these parts are more vigorous than the older center parts (if you wait until August 15th or so, you'll be able to see this). Then you just re-plant that younger outer rhizome section with some roots attached, barely covering the top of the rhizome.

It sounds like your Iris maybe are in some standing water, so they could be Siberian or Japanese or ?? Iris, in which case I'm a little less sure how you divide and replant.

    Bookmark   May 7, 2009 at 5:09PM
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windwhipped(Z4 WY)

Take a look at the FAQ's on the Iris forum. I haven't checked there for a long time, but as I recall they had some great info re digging and dividing iris.

The short answer is no, digging up a few isn't going to work. Irises die out from the center out. So yes, you need to dig up the whole mass, discard the rhizomes in the middle that have stopped producing, as well as anything mushy and replant some of the outer rhizomes. (Again, much better, clearer info in the Iris FAQ's.) This is usually done mid-summer, after the irises have bloomed. If you do it now, you will lose any bloom for this year. Also, when you replant you do need to leave the top of the rhizome uncovered - planting too deep kills them right off!

Sorry, believe me I wish it were as easy as just lopping off a few at the edges.

    Bookmark   May 7, 2009 at 5:14PM
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Dan Staley

Yup. That was the chore for a long time in Sacramento, digging up the iris beds every 3 years. I'd always bring people by and admire them in front of them, then they'd get a grocery bag from Dan'l. ;o)

One of my friends has a childhood friend who breeds iris in WA state on acreage. Talk about work...

Your task after digging is replanting them in a way where you control their growing direction to make it easy on yourself in 2012.


    Bookmark   May 8, 2009 at 12:24AM
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Aha! Thank you all!!

They must be the tough beardeds because that is what they look like when they bloom. I wish I had standing water...so dry here.

But, we had that four foot dumping of heavy, wet snow and then warm weather right after. It melted for a change. sometimes it seams like it just evaporates but this stuff was wetter than a swamp! Might have happened then.

Also, they were here when we got here so I have kind of ignored them and classified them as "oh, how nice".

But, since I have built up the Siberian irises that are in front of the boulders (the beareds are behind the boulders) and have also added crocus and tulips to the existing daffodils, I want the irises to do well, too. Actually, I want them to do well anyway, I've just run out of time to ignore them!

I will check the iris forum. Gee, sometimes I forget there are other forums here!

Dan, I have been given so many bags of irises in my life from people almost willing to bludgeon me on the head if I don't take them!! Funny how that works. When I drive by yards that are covered, I just am glad they aren't my irises!

Although, I seem to be collecting more and more somehow...Who brought all those irises to the fall swap?? I managed to take a bunch home. Thank you.


    Bookmark   May 8, 2009 at 1:39AM
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david52 Zone 6

I dug up a totally overgrown patch of the plain ol' dark purple iris and stuck the rhizomes all along the top edge of my pond. I'd heard/read somewhere that they are swamp-related critters or something.... Anyway, they bloomed spectacularly for two years, and now, maybe one or two out of hundreds will bloom.

However, the rhizome mass helps stabilize the bank, and they're spreading happily.

    Bookmark   May 8, 2009 at 9:05AM
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