Iris: Unsure which type and extra long rhizomes.

zsjh7ssnddQNQ-AKxg · April 2023

I have been taking some plants from my grandparents former garden before the house goes on the market.

Today I noticed some tall "iris" looking things in amongst undergrowth in a shaded area. They were easy to pull up from the ground. The rhizomes on some of them are huge over 1ft/30cm in length.

Question is, do I cut some of the rhizome away as they are struggling to stand up and don't appear to have too many roots? Should the full rhizome be exposed to the sun, (as I appreciate the rhizomes like to be baked). Should I be cutting back any foliage, though if they do flower this year, it should be relatively soon I guess?

Any thoughts or advice on what and how to maintain is much appreciated. I have found conflicting information and do not wish to kill of the plant.

Thanks in advance.

Fairygirl · April 2023

Hi @zsjh7ssnddQNQ-AKxg - have you got any photos of the plants? That will help determine the type

However, it does sound like they're bearded Iris which need the rhizome kept on the surface of the soil. When they get large they tend to spread in a circle, with the centre dying off and becoming less productive. Is that what you mean about how they were growing?
When they get like that, they do benefit from being split and re planted, so that's what would be ideal. You cut through the rhizome - into pieces about 3 or 4 inches long, and with some foliage sprouting, and that should then be fine when firmed into a pot. If the foliage is long it should be cut back to a few inches or so.
If the foliage is long just now, it suggests it's either last year's foliage which would be quite tatty, or it's a different type. Most bearded irises wouldn't be very tall yet, but if you're in a warm part of the country, that may be the case

GardenerSuze · April 2023

Six to eight hours of sun is needed to get good flowering.

Cambridgerose12 · April 2023

A photo is essential, as a number of iris produce rhizomes, but have very different needs...

Fairygirl · April 2023

That was my concern @Cambridgerose12. It could be a flag Iris, as their rhizomes can get huge and very tough - the OP may not want to have loads of those!

zsjh7ssnddQNQ-AKxg · April 2023

This is the longest rhizome at 38cm/1ft 3i. Any further thoughts/advice would be much appreciated, as I’d love to see them flower.

Thanks in advance.

bcpathome · April 2023

Beard iris I reckon . Had one given to me( another thread) and they look just like that . You can cut the end with the growth on ,off ,like the one I was given ,and cut the rest into bits and grow them in pots to take away with you .

zsjh7ssnddQNQ-AKxg · April 2023

@fairygirl @Cambridgerose12

Thank you @GardenerSuze @bcpathome

Fairygirl · April 2023

You can certainly cut away some of the rhizome, but the bits you cut off won't grow - they'd need to have roots and some top growth for that.

@zsjh7ssnddQNQ-AKxg- the ground it was growing in - was it wet, dry? Any idea of the flower colour? You said it was in undergrowth, so was it very shady? What else was growing around it?
Those can all be indicators as to type, although if it's a bearded iris and was struggling due to the site, that could be why the rhizome is so long. It could still be a flag iris rather than bearded, so the conditions required would be very different.

zsjh7ssnddQNQ-AKxg · April 2023

@fairygirl Thank you for the advice about cutting rhizomes.

The ground was somewhat damp, but no surprise due to the amount of rain and shade in the area.

Surrounding plants included blue/whitebells, wild rose, sticky weed and dandelions with two conifers.

Parents said they gave my grandparents some blue iris years ago, but not sure if these are then. I’ve not seen them flower, should I cut back the foliage?

How best do I cut the rhizome without allowing a virus or pest to enter and kill the whole plant?

How deep will the roots grow?

Thank you.

Fairygirl · April 2023

The foliage doesn't look right for the sibirica or ensata types which like consistently moist soil, and don't mind shade, and don't tend to have such thick rhizomes - they're more bulbous, so it's more likely to be something like a bearded iris which just hasn't had the right conditions. If those are the ones your parents gave your g'parents, then they aren't flag iris. Most irises come in blues so it would be hard to narrow it down to type other than ruling out the flag ones.
Conifers can deplete the surrounding soil of moisture, but in wetter areas it still stays moist enough for many plants. I think all you can do is pot it up and see what happens.
Don't worry about cutting the rhizome - that's how rhizomatous Irises are propagated. In late summer/early autumn, clumps are split to make several new plants, and as I said earlier, many of them eventually spread to form a circle, with the middle section dying back, and they become less productive at that point, so splitting them is beneficial.

I'd cut back the foliage so that there's just 3 or 4 inches, and use a pot that has enough width to take the rhizome, and 3 or 4 inches of that is also fine, but it needn't be exact. Keep the rhizome on the surface. I think we have to assume it's a bearded [or similar] type - there are beardless ones as well, but the general care is the same.
The roots will be pretty shallow [ I can't see any at all in your pic!] so it may need some basic support until established. Twigs, small canes and string - something like that. Water it and put it somewhere sheltered but with decent light. You'll then need to keep an eye on it, and wait until something happens, and that could be a while. Make sure it has adequate water while potted. As the roots get down, pot it on into a bigger pot at the same level. Eventually, the roots on bigger irises get quite deep, so it'll need planted out in the ground, but it's a waiting game. It isn't likely to flower this year either, so patience is needed.

Iris: Unsure which type and extra long rhizomes.

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