[mdjlucan]

Is it too late to separate them now

[greenjay]

I am no expert with leeks but I would personally separate them. at least the ones in situ will have the chance to develop. the soil should be warm and damp so the transplants should take easily.

[New shoot]

It is late, but you could separate them and as Greenjay says, they should take.  They probably won't grow as big now as they will run out of summer.

If you leave them, you will still get something, but they might be better pulled and eaten over the autumn.  You can sow leeks late like this to get baby leeks for autumn, but I'm not sure they would overwinter.  They may do, I've just never tried it, so I don't know.

[Nikkithefoot]

When I used to visit my grandparents in Scotland they were only just splitting and putting out pencil thickness leeks now and they grew to a reasonable size.
Certainly worth a shot.

[mumofstig]

I'd thin them leaving them about 6ins apart and replant the thinings.

That way you'll at least get some that will grow to full size.

[Goosegirl]

When you separate them keep your fingers/thumb around the base of the leek you want to stay then gently lift the other one so you won't disturb the roots too much.

[shedmeister]

Stick em in a stir fry. Lovely scoff

[al78]

I had some leeks that I had sown directly outdoors and then forgot about thinning. I dug them up and transplanted them yesterday. It gives them a chance to further develop, and some of them are virtually at baby leek size. I'll see what they come too during Autumn, if we have a mild one they might grow a bit more than normal. We rarely get winter in the SE so they might continue growing slowly over the extended autumn (aka winter) months, this happened once with PSB which cropped from summer through to the following spring during a mild winter.