Dutch iris--different dividing rules?

deanna in ME Barely zone 6a, more like 5b

17 years ago

I've read the FAQ and searched the forum and haven't found info on dividing Dutch irises. I'm new to gardening, and I've read that Dutch irises have a different type of root than bearded. Because of that I'm not exactly sure about what to do.

I have some grown by the previous owner of our house that so clearly need to be divided it's almost sad. My question mainly involves dirt and trimming when I divide. Should I keep a healthy amount of dirt around the root when I transplant (which means no trimming), or should I knock off all the dirt and trim it? Do I trim the root the same way the FAQ says to trim a bearded iris?

Thank you for your help!

Featured Answer

gardengal48 (PNW Z8/9)

17 years ago

Like any other bulb, each bulb is an individual plant and while they may naturalize (and I've never seen a bulbous iris accomplish this to any significant extent), you will never get a clump 5' across! What you are describing are NOT Dutch iris!

Pictures would help, but yours sound like Siberians. Dividing is recommended in the fall for these as the bloom cycle will be less affected, but it can also be done in spring. You may just miss a season of bloom doing so then. I've grown an awful lot of different Siberian (and Cal-Sib hybrids and other species) iris over the years and they tend to die off in the center as the plants age, leaving a doughnut of active growth on the outer perimeter. I've had the best success dividing by using an old pruning saw to slice the clump into manageable pie-shaped wedges while still in the ground, then digging and removing them. You'll want to remove and discard the old inner portions as these will not produce.

FWIW, there are countless species of iris and many dozens of hybrids and these include bulbous, rhizomatous and fleshy rooted forms. They all get handled a bit differently.

ps. there are no "rules" of plant division - only guidelines :-)

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Comments (6)

Chemocurl zn5b/6a Indiana
17 years ago
I'm new to gardening, and I've read that Dutch irises have a different type of root than bearded.
Yes, Dutch irises are bulbs and are planted differently than bearded iris rhizomes.

I have some grown by the previous owner of our house that so clearly need to be divided it's almost sad.
Are you certain that they are Dutch? I cannot keep Dutch irises going here in my zone, though I have heard of others who have them even in your zone. Often when they are sold, they are listed for warmer zones than mine or yours.

Are you sure they maybe aren't Siberian iris?

Sue...chemocurl

Here is a link that might be useful: How to plant Dutch iris bulbs
deanna in ME Barely zone 6a, more like 5b
Original Author
17 years ago
Wow. Now that I search, the Siberian and the Dutch look alike. My purple iris could be either! The foliage is long, thin, and still looks great, but I can't find any great pictures on the web of foliage because most of the pics focus on the flower. My foliage is also very mature, one clump being about 5' in diameter (yes, it certainly does need dividing).

The only clue I have is that I have one white iris that I think is a Siberian (only because my local nursery thought it looked like a Siberian but was not positive) and it has brown seed pods atop a green stem. These purple irises have fatter green seed pods and the stem is still nice and green. The white iris flower seemed "flatter" and by that I mean that when it bloomed it seemed like it didn't have those center flowers that raised up as high as other irises. Also, the purple irises definitely bloomed earlier than the white iris. I gather from my reading that Dutch irises are shorter, but these irises are about 2' high, which fits either description!! Should I just dig them up and then decide what they are based on the root? At least Dutch and Siberian have different roots!
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deanna in ME Barely zone 6a, more like 5b
Original Author
17 years ago
OK, so since the Dutch iris comes from a bulb, I wouldn't expect it to expand into a 5' growth? Is that right? Maybe that's an obvious clue?!

Since Dutch irises are bulbs, will they stay compact and not spread?
Chemocurl zn5b/6a Indiana
17 years ago
Since Dutch irises are bulbs, will they stay compact and not spread?
Since I cannot even keep them alive, I would say they certainly would not make an 5' clump in your area.

I have Siberians, and yes, the foliage is still green and neat looking, and when I dig them, it will be a bear I'm sure with a massive clump of roots. I dug some once before, and gave them away. I'm not sure how to divide and reset them. I would imagine that maybe one would somehow get them apart and in maybe smaller (as in 2-4'hunks) and plant them at the same depth.

Hopefully a Siberian person will check in here shortly.

I posted about mine last year as I didn't know what type of iris they were. There are pics

Sue
mad_gallica (z5 Eastern NY)
17 years ago
While I haven't gone after 5' Siberian clumps, I have successfully attacked 4' clumps.

If you buy Sibs, you want to order them for spring delivery. Established clumps can be dug and divided either in spring or fall. The difference is that what you are working with in your garden is going to be a much larger clump than what you will usually buy.

The easiest way to divide Siberians that I've found is to use the two-fork method of division of the clump while it is still in the ground. The link below is to somebody's explanation of how to do this.

Here is a link that might be useful: Two Fork dividing instructions