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How do I divide irises
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Posted by Pam_Em WA (My Page) on Mon, Mar 1, 04 at 0:44
| Please help. Last year I bought about 20 irises and planted them around a new garden within a Fawkner Jap Box hedge in a parterre design. Well they went berserk and not having any experience with them before, I planted too many and too close to the hedge. So now I have to shift some. Would someone please tell me do I simply shove in the spade and lift the whole clump out? THen what? Do I divide up the rhyzomes or whatever they're called and put them in a container to plant in April or May? Do I discard any part of them and should I cut them into a fan shape like they were when I bought them? Is it too early to lift them now? Most are yellow though I wanted purple too and some never flowered (yet). I need blow by blow help! |
Follow-Up Postings:
RE: How do I divide irises
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Depends what type they are, but most irises should be divided and planted by mid Autumn. They make a lot of growth over autumn if watered, before they become doramnt in winter, so the earlier they are back in the ground, the better.
If they are bearded irises, lift the whole clump with the fork, cut out all the dead roots, and cut the tops back to about 20cm, and gently pull off any dead leaves. Prise the rhizomes apart, then pull or cut the larger ones where they attach to the mother rhizome (the one that flowered). Most mother rhizomes can be discarded, but if they have lots of tiny increases starting to grow, plant them in some light soil, and they will gove you a new clump.
Your purple one may bloom next year. Some irises do not bloom every year, and take a year or so to settle in before blooming.
The reason for trimming backthe leaves is to prevent the wind rocking the rhizome. If the rhizomes rock they do not contact well with the soil, so do not form a firm root attachment.
Hope that getws you started. If you have any more problems, let me know.
Cheers, Jan |
RE: How do I divide irises
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| Also, don't replant the rhizomes too deeply - leave the top of it showing above the soil. Bearded iris will generally bloom the first year from division if it is done soon after flowering is finished. Using a knife or secateurs to give a clean cut, cut back each rhizome section to within a couple of centimetres of a leaf shoot. Plant the divisions straight away. Prepare your soil with a handful of complete fertiliser and a light dusting of lime. |
RE: How do I divide irises
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Rhizome depth should vary with soil type. If you have light sandy soil, you can cover the rhizome with up to 2cm of soil (as Barry Blyth does at Tempo Two). This helps the roots to establish properly, and hold the plant in the soil. Irises planted too high in sandy soil may fall over when in bloom. If your soil is heavier, the sun cannot penetrate so easily, so less soil should cover the rhizome.
Either way, they will often pull themselves down, or grow up above the ground, and find their own depth.
They are amazingly hardy. |
RE: How do I divide irises
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| Sorry Sparaxis. I've never had sandy soil ... only the blood, sweat and tears variety (sigh). I stand corrected. I love bearded irises and have lots, from extra tall ones (which blow over in the wind anyway - my fault for living on the top of a hill), down to tiny miniatures. |
RE: How do I divide irises
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| THanks Sparaxis and Wombat, I am so impressed to get an answer so fast and in such detail. They are Bearded iris and looks like I ought to do it in May or therabouts. Gulp. I'm glad they're hardy. It is windy but I have great soil in that garden and water is good. I am going to have so many though. Ought I plant singly and how long should I leave it before planting after I have dug them out? |
RE: How do I divide irises
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Haha - Wombat - same here. I have just been digging mine out of the concrete that was mud in winter :-( Have amended my iris beds with copious quantities of clay breaker, rotted cow manure (not humanure) and black sand. Rotary hoed it all in, and it didn't look a lot different - time will tell.
Plant them ASAP after digging. If you don't plant all, make sure you keep a few from EACH clump rather than the biggest like I did with my first lot. I ended up with all one variety (white0, as the rhizome size can vary from clump to clump, and I had given the small ones away to friends who ended up with a lovely assortment of colours. We live and learn! - LOL |
RE: How do I divide irises
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| You don't have to wait until May to divide. You can divide straight after they have finished flowering. If you divide now they will have a chance to establish themselves before winter and there will be chance of them flowering next season. Another word of warning to add to Sparixis' - some varieties are much more vigorous than others and will form HUGE rhizomes over the top of others, if they get the chance. It then becomes almost impossible to figure out which bit belongs to which plant. I used to have a beautiful deep apricot ... but I have lots of a very tall, bright yellow!! SO.. leave a bit of room between them. Paddle pop sticks and permanent markers make unobtrusive little signs. |
RE: How do I divide irises
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| THanks again, Wombat and Sparaxis. I shall start this weekend then. I don't have the room to plant as many as have grown from the ones I planted. And I would still love to have purple ones! I'd hate to throw them out but will try to give some away. Have copious Day lilies too and love them. Same deal, I thought I was getting one colour and ended up with 4 different ones. I'll let you know how I go. |
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