[Growster...]

Lots of comment, advice and help - marvellous, and thanks!

As for transplanting, it is a great pastime in spring, in the greenhouse, 'Desert Island Disks' blaring out (on earphones if a rock star is being grilled),  and a newly sharpened dibber, (not the one I'm going to describe in another post)!

Heaven!

[Goosegirl]

I transplant mine twice according to the Robinson's Mammoth Onion website. Once when they reach the "crook" stage and again when they have three or so leaves and it works far better for me as I get to the "pencil" size recommended for planting which I never did before.

[Growster...]

Goosegirl!

Marvellous - thankyou, there's enough encouragement here to go ahead!

The target is 240 plants, so, soon, when I find out how to post a picture, I'll explain my prototype 'Growster Leek Dibber Mark 1'! That many dibbled in by hand doesn't bear thinking about the knees go first, then the elbows, then the neck and finally the resolve!

Mind you, if I search hard enough, someone else somewhere will have done something similar...