Irises forum: How can I keep rhizomes on top of soil?

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Jun 30, 2013 4:58 PM CST
Our ground is heavy clay with some compost added. I have found that if I can keep the growing edge of the rhizome just at the top of the soil it prevents rot from starting. So I start them this way, on a raised ridge area, but the next spring they are inevitably burrowing into the ground and I have to take my finger and clear out a drainage ditch for them. Last year with a catastrophic drought, it wasn't a big problem, but this year we have had rain rain and more rain. Do you think the problem is not firming the soil down enough when I plant them?
Name: Lucy
Hamilton, MA (Zone 6b)
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Jun 30, 2013 6:56 PM CST
The roots should grab onto the soil & there is less trouble. You can brush soil off the rhizomes but not disturb the roots.

Jul 1, 2013 5:56 AM CST
I guess you didn't understand my problem. It's a little hard to put in words.
Name: Tom
Southern Wisconsin (Zone 5b)
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Jul 1, 2013 6:03 AM CST
I know what you mean, Some irises seem to bury their rhizomes even though you try to plant them properly. I guess I let it up to the plant to put their rhizomes where they want them. I start them off right, and then they grow the way they want to. They seem to do fine. Unless you're having lots of problems with crown mold, I'd leave them alone.
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Name: Arlyn
Whiteside County, Illinois (Zone 5a)
Irises Beekeeper Region: Illinois Celebrating Gardening: 2015
Jul 1, 2013 7:09 AM CST
I agree Our soil is very sandy, and drainage is not a problem. I plant with soil to the top of the rhizome, on a slight "mound"( just so run-ff water does not carry more soil onto the plant). I've noticed that some cultivars will grow deeper, while most seem to grow themselves shallower. I think the iris know better what's good for them than we do, most times. If rot has been a problem for you, perhaps mixing a little sand into the planting hole would help with drainage? Also, don't crowd your plants....In my garden , it's always the crowded areas that suffer worst from disease...letting the air flow around them, and the sun reach the plant base, are the 2 best controls for disease, in my opinion....Arlyn
Name: Kent Pfeiffer
Southeast Nebraska (Zone 5b)
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Jul 1, 2013 10:07 AM CST


For what it's worth, mixing sand into heavy clay soil gives you two of the basic ingredients of concrete. All you need to do then is add water, and you're all set (literally!).

We have clay soils here. Irises will grow OK in straight clay, but they perform better with heavy amendments of organic matter. One of the things I've learned about gardening in clay is that tillage is something to be avoided. When creating a new bed, I just spread a 2 - 3 inch layer of coarse compost across the area and plant into that. The compost drains quickly, but it also acts almost like mulch in keeping the soil underneath moist. So the rhizomes stay relatively dry, but the roots have access to moisture.

Jul 1, 2013 3:07 PM CST
I've heard that old wives' tale about sand and clay, but I don't believe it. I like the planting into coarse compost idea, and since I have a pile handy, I think I will try it. I think that slugs are eating away at the leaves that touch the ground causing the rot. Haven't put on sluggo yet this year because you are supposed to reapply after a heavy rain, and it has been doing nothing but raining!
Name: Paul
Utah (Zone 5b)
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Jul 1, 2013 4:02 PM CST
I do not think it is very PC to say old wives' tale...wouldn't old mates' tale sound better? Hilarious! Hilarious! Hilarious! I have heard numerous times from plantsmen I respect that clay and sand=cement. Fine clay grains and large sand grains = cement. .....they always recommend coarse compost. I concurr.
Paul Smith Pleasant Grove, Utah

Jul 2, 2013 6:57 AM CST
Portland cement is made in kilns in Portland, I believe, but I am not an expert. What would "grit" be? coarse limestone?
Name: Arlyn
Whiteside County, Illinois (Zone 5a)
Irises Beekeeper Region: Illinois Celebrating Gardening: 2015
Jul 2, 2013 8:12 AM CST
Portland cement is made by baking limestone(85%), and other minerals( clay is one of them, along with iron oxide and alumina(10%)) in an oven, or kiln. The resulting cinder is then ground to a powder. Clay is a mineral "soil", with very small particle size( a powder, actually). As mineral soils increase in particle larger is silt, next sand, then it's into gravel, and from there boulders, and mountains, I guess! Rolling on the floor laughing . Concrete is made of Portland cement, aggregate( sand, and either crushed limestone or gavel), and water. Adobe is made from clay( in a "mud' state) and either straw, or grass, mixed and baked in the sun. if you bake the adobe blocks in a kiln, you have what we call bricks( you don't need the straw then, as the kilning gives enough strength to provide tension strength). Basically, the larger the size of the particles, the less they want to clump together.that's probably more than you wanted to know, Catlin! Rolling on the floor laughing ....Arlyn
[Last edited by crowrita1 - Jul 2, 2013 10:23 AM (+)]
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