Irises forum: Poor soil causing stunted irises?

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Oregon's high desert (Zone 6a)
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LynnDel
May 23, 2018 4:01 PM CST
Last fall a landscaping project required that I move about 30 irises in a hurry. This spring I am discovering that the moved TB irises are only making it to about 20" in the bud stage, and one that has bloomed is a shrimpy 7" tall. I'm quite sure it is not a mini, or at least wasn't when I moved it, because I had no minis.

It turns out that the soil where they are now trying to grow is mostly wood chips. I had seen wood chips when I made the move, but didn't realize they were the majority of the soil component in that area. The leaves have good color, so at least they don't appear to be in a life-and-death starvation struggle -- but irises can trick you that way.

My eventual goal is to move the irises to new locations and do extensive soil amendments in this area before planting irises there again.

Questions:
1. Would it be a problem to put topsoil in the area while the irises are still trying to grow there? Or is there some other temporary solution for them in their current location? I'm hoping to ID them them before moving them again (my "helper" disconnected the labels from the clumps during landscaping).
2. Should I move them out of the poor soil right away -- or wait until the usual iris transplanting season?

Thanks in advance for your help.

LynnDel
South central PA (Zone 6a)
Irises Region: Pennsylvania
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DaveinPA
May 23, 2018 4:18 PM CST
If they are growing okay although stunted I'd leave them but maybe put some ground limestone on the bed as wood chips are acidic most of the time. A little low number fertilizer [5-5-5 or 8-8-8] sprinkled on might help also as decaying material uses a lot of nutrients from the soil. If water is allowed to lay on the bed don't keep them there at all as it is the death of bearded irises. If you amend with top soil put on top of the bed do not bury the rhizomes with it unless you normally keep rhizomes completely below ground level.
I have mostly builder "top soil" of clay and rock; most were stunted after a move and further stunted because of the poor soil. A big improvement the second year after some amendments added between the clumps.
Name: Arlyn
Whiteside County, Illinois (Zone 5a)
Irises Beekeeper Region: Illinois Celebrating Gardening: 2015
crowrita1
May 23, 2018 4:24 PM CST
Dave has good advice, and, adding some nitrogen is definitely a good idea...the breakdown of those "chips" is tying up all the available nitrogen in the soil !
Name: Robin
Melbourne, Australia (Zone 10b)
Region: Australia Irises Garden Photography Cat Lover Seed Starter
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Totally_Amazing
May 23, 2018 7:33 PM CST
I agree with Dave and Arlyn. I once had wood chip mulch around my irises and they stopped increasing and blooming. I removed the mulch and applied pellet fertilizer and Triple 10 fertilizer in liquid form which worked well.

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