The baby rhizomes of my bearded iris are spreading themselves out away from the main plants and I would like to move them nearer to make a big clump. What time of the year should I do this. i.e. can I do it now as they will most prob be too young to flower this year.
I wouldn't split the clumps now, I'd do it after flowering - discarding the older central rhizomes and replanting the newer ones, giving them a chance to grow on through the summer to build themselves up for the following year.
The reason they're looking 'spread out' is probably because the older rhizomes are past their best.
You can split them now - it just means you won't get any flowers till next year. As Dove says, the big bits are past their sell by date, so it's best to get rid of them and keep the new, younger bits. I split some when I moved here at this time last year as they were in pots and very congested, and they wouldn't have flowered much anyway. They've grown on well and I should get a nice lot of flowers this year.