The Process of Division

As we got towards the end of dividing nearly 700 plants there was quite a rhythm to the process and it became much faster. I wonder if the big Iris nurseries do this task by hand or if there is some machine that lifts the iris for them?. If is it by hand then my hats off to them for it is hard work and we only had small clumps of 60 varieties to work on!
All dug up, one plant ready for propagating.

All dug up, one plant ready for propagating.

Stage one is digging up the congested rhizome, this was one rhizome that’s been in for 2 years. Tough growing conditions, drought and wind, so it has done well. The dead and diseased is removed first, that’s leaves and rhizome,  then the soil to the roots knocked off as carefully as possible though by the end of a week of this you realise the roots are pretty robust and can take a fair old knock! As the ‘solid knocking’ happens the individual ‘new’ rhizomes emerge, growing into and onto of each other they can be quite the jigsaw to separate but it is satisfying to feel them ‘tear’ apart and the roots disentangle and the new rhizome is parted from the old. It helps that our soil is dry as dust at the moment!
Beginning to tease the rhizomes apart

Beginning to tease the rhizomes apart

Once divided the tidying continues, leaves are cut back to 3-6 inches and in a ‘V’ shape to allow water run off. The reduction of leaves reduces stress on the new plants root system while it establishes. Not everyone cuts the in a ‘V’ but mostly Iris nursery people seem to, so I am following that much more experienced crowd.
Hairy roots of the Iris plant need a bit of trimming

Hairy roots of the Iris plant need a bit of trimming

Though some of the rhizomes are a little woody some are producing nodules of new growth at a rate of knots. Oh So Cool had very little top growth but about 4-7 nodes on each new root, a slow starter perhaps but a bumper crop next year?
Endless recording and note taking

Endless recording and note taking

We keep records, increasingly, records of everything. I have turned into a nerd almost without noticing. It is required to some degree – Plant Heritage like lots of info on plants behaviour. But it is also the curiosity of which grows best?, what sort of rhizome it makes?, is it more or less like it’s parent? how many are we likely to get in coming years?  And the more you work with them, take care of them, the more interested you become in how they grow. This year we numbered all the rhizomes. One or two got ‘lost’ last year and you have to wait for them, not only to flower but then there is the issue of identifying it if it’s one of the similar varieties – I know there are very specific differences in each variety but trust me when I say, not every root produces a truly DIFFERENT plant, sometimes it’s not so obvious!
PH require plant variety to be numbered, the source indicated and the year of acquisition stated. We also keep records of quantities and yield and who we have sold to (I told you, nerd) and of course details of the plant behaviour, growth, vigour, flowering dates, length of flowering, no. of flowers (you see, nerdy bordering on OCD), root vigour and volume, growing conditions….I will stop now as it’s clear I am a bit obsessed!
Iris Labelled with waterproof pen and THE black plant label

Iris Labelled with waterproof pen and THE black plant label

Suffice to say gathering intel on the varieties gives me pleasure and it’s useful to know which can handle really tough conditions an which turn up their toes in disgust.

Each row is labelled and each plant numbered. This year we’re trialling rows or 4-5 rhizomes instead of circular groups of 3. We are also noticing how 1 rhizome, when it has space to spread is MUCH more prolific than a few close together. Can it be as simple as the single has less competition for food, water and nutrients?

DIviding Iris Purple fans

The soil minerals seem to have affected some of our rhizomes. Having thought this  a variety (Poker Chips) ‘feature’, upon digging out others it’s clear that all the rhizomes in the area are purpley red to some degree and none of the others are remotely coloured. Wonder what the mineral is?
DIviding Iris replants
some end up here and some end up here
DIviding Iris pots
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  • Jacqueline Gum

    oh my this looks like a mountain of work! Kudos on getting it all done. I’ve tried splitting Iris before, but only a few survived. Maybe the V technique is what does it?

    • Tell me more! what happened to them? What zone are you in? (i.e how hot/cold do you get summer/winter)
      The V technique also stops windrock, which in turn helps them get roots established firmly and so growing.

  • Rosalind, as you know I love gardening and always appreciate learning more. The info you had about record-keeping, labeling each iris plant with magic marker, and the different things you look for – which ones grow best, which ones turn out like the parent plant, etc. – are things that I can use in my own garden.
    That is an amazing amount of work accomplished by you. Thanks for sharing this. Appreciate it.

    • Thank You Lenie, I do sometimes wonder if this sort of post might just bore everyone rigid 😀 though it’s a useful thing to point at for people new to Iris division!
      I’ve actually gone from a Sharpie pen to a bullet proof permanent waterproof marker. So far so good.

  • I planted some bearded iris years ago, but they didn’t grow very well. I was patient the first year, and then the second year they put up flower stalks that were six inches or less. My grandpa chuckled when I told him my struggles and said they are such an easy flower to grow. I don’t have great luck with tulips either if I plant them directly in my yard’s soil which tends to be clay-like in consistency, though I’ve amended it a bit over the years. A few neighbors have lovely clumps of irises, but not me.

    • Your Grandpa is right they are easy to grow but but but can be sulky on occasion.
      Clay is their nemesis. Not because they don’t like it per se but they don’t like wet feet in winter. I have found this is pretty much the only thing they hate. It’s all about drainage!
      If you can then dig them up and where they will be replanted dig in a bag of horticultural grit, or gravel or pea shingle, 6-10mm stuff. You want it gritty. If in doubt dig in more.
      Plant them in this keeping the top of the rhizome on the surface of the soil (as it bakes in the summer sun it gathers energy for next years flowers) and they will be happy. Bearded Iris mostly hail from mountainsides. Think windy, rubbish soil, dry. If you really want to give them a hand feed them after flowering with a potash feed, here it is Sulphate of Flowers, not sure in the USA.
      Tulips are another post 🙂

  • Thx for these detailed instructions on how to propagate irises. I’m just in the process of cleaning out my garden and getting rid of unwanted plants and weeds. It’s a never-ending job!

    • I agree, a pause button for weed growth would be VERY helpful!

  • Looks like a lot of work. I admire your commitment.

    • Actually I hold what is called a National Collection of Iris, one particular kind hence the dedication (geek level record keeping). It is required.

  • I’ve always lived in cities as an adult so I’ve never had a back yard. I don’t know pretty much anything about gardening for that reason. This was interesting as I learned how much consideration and thought needs to go into really effectively keeping up a garden. Thank you for sharing.

    • Gosh I don’t want you to think this is ‘normal’, it really isn’t, As I mentioned to Ken I have to keep these records for the National Collection otherwise I wouldn’t. I do keep a notebook on what is doing well, not so well, flowering, failing, fruiting and so on so that I can look back at triumphs and disasters year on year but it’s rather more random than these Iris records.

  • ukmaggie45

    Thanks very much for very clear and informative post on how to divide bearded irises.

    I’m afraid we did our (possibly) irises at the wrong time of year – back in May(ish) if I recall correctly. They’d been growing under rhubarb plants for years (we’ve only had our allotment 2 years) and we needed to move them to make space for a bean bed. I say “possibly” irises as they haven’t flowered, I suspect because shaded too much. At least they are in a sunny part of lottie now, so we’ll just have to hope we get flowers in the next couple of years… If not I suspect they’ll be going to that great compost bin in the sky! 😉 But we did at least want to give them a chance. Think there might be a couple more still need moving, so we’ll get onto that in the next couple of weeks.

    • The will definitely thank you for moving them from under the rhubarb! If you moved them in MAy then they will probably not flower until next year (29016) fingers crossed for flowers…

  • I’ve never done anything like this Rosalind but the photos are wonderful and you make it sound doable even for a non-do it yourself like me!

    • I’m a great believer in the resilience of all plants which is handy when they come into my gardens for the first time.

  • God bless you, this looks overwhelming to me! It’s your skilled and gifted hands that make my world more beautiful, thank you

  • William Rusho

    My garden was started by my mom, since she has been gone I have
    tried to maintain it. There are tons of iris’s there, and thinning them out
    would help a lot, thanks for sharing this information with us.

  • I know nothing about gardening. You made this job sound easier than I thought it would be.

  • I’m not a gardener – my father was but that gene didn’t get passed on. I admire your tenacity.

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