[fletch]

I have a really large patch of these, all overgrown with couch and nettles and I want to clear the area.

All I read on dividing Irises says to do it after they have flowered in early June. I really want to do it now (i.e. tomorrow) as if I leave it till June the whole area (approx 6ft x 6ft) will be a tangled mess of weeds and nettles, like it was last year.

Any advice?

[richyrich7]

Bit of a risk I suppose but if you need to do it do it, you could always take the flower heads off before they fully form this probably would give them a chance to get a stronger root system down ready for next year . Give them a good dressing of bonemeal or blood fish and bone to help them on their way.

[Trillium]

I divide my irises whenever I feel like it. And if the leaves are only just coming out, it's an even better time for a novice to divide them.
With a spade or shovel, scoop out a good sized lump of soil all around the iris clump. If the bed is simply too large, then you'll need to push a sharpened spade in between a less crowded space among the plants, but do start at one end of the bed.
Pull the clump out with the soil and hose it to dampen the soil. When done, hold the stem close to the roots and gently tease out the roots from the soil. Watering makes it easier and the roots should slip out. You might need to untangle weed roots at the same time or after you separate the first iris plant.
Continue the whole process until you reach the end of the bed. Irises don't like too much water so don't soak them in a bucket of water while you dig the others out.

Replant asap into a fresh bed, lightly manured, with compost, bonemeal and water them in afterwards.
If the leaves are quite large, then you'll need to literally cut them down halfway and new growth will come out later. It's iffy whether or not you'll get flowers this year, but at least you won't have a prominent crop of weeds.  

[fletch]

Oh good, thanks for that. The leaves have only just started to come through, they're a couple of inches high at the most, plus I've just bought some bonemeal.
If I miss out on flowers this year then so be it, they hardly flowered last year anyway as they were so choked.
Thanks again.

[Trillium]

Sounds like you've picked a good time to divide them. You won't have to cut down the leaves either since they're so small. Just be careful while handling them so not to break off any small leaves.

One trick I now use with fabulous results is to mix in or top dress each plant with alfalfa pellets (not cubes).  Mostly it's horse feed. I buy a 20K sack for about 5 pounds equivalent and it lasts a few years (kept safe from vermin). You can't overuse this. I either mix in 2 generous handfuls per planting hole or top dress with a generous handful yearly. Soon as you've finished setting the pellets down, water immediately. This makes it unpalatable to vermin who won't touch it. Leaves become stronger, greener, and flower stalks are larger. Good for roses as well. A healthy plant is less attractive to pests.

[fletch]

Well I never got around to it today as it's been blowing a freezing gale (and heavy snow forecast tomorrow  :evil: ).

I did have a poke around and it's much worse than I thought, the nettles have formed a mat (the stems/runners on the nettles are as thick as a pencil) with the Iris growing through. However, the patch of Iris is easily 5ft x 4ft so I think I'll try to salvage what I can, pot them up for the time being and then totally clear the whole area, it will need some serious hard graft and probably weedkiller too.

Some of the rhizomes just broke away in my hand, sections about 10inches long, but with roots attached. Are they worth potting up?

[Trillium]

You can easily replant most parts of the rhizomes other than the actual rootlets which have no 'eye' to sprout leaves from.
I've had couch poke through various roots, including potatoes, but they're easily pulled out. Usually looks worse than it really is.