[mollyblob]

My leeks have been looking very sorry for themselves the whole way along, especially so when I went out one day and slugs had eaten every one down to the soil.  Aargh!  In disgust, I left the tray where it was, writing it off as a bad job.  I happened to notice the discarded tray the other week and somehow they've all come back from the dead, and are now much sturdier than before, standing straight up, but still pretty skinny (biro refill thickness as I've seen someone here describe them!)

Should I put them into their final positions now, or wait till they've fattened up to pencils?  I'd hate to kill them after they thwarted the slugs :-)

[peapod]

Put them in, mine were like blades of grass when I planted them 

[theakston_uk]

I'd say plant them out too. Mine like peapod's were very thin when they went in the ground (people say wait until they are pencil thickness, I'd still be waiting now though) and have started to thicken up nicely, it's amazing how quickly and how much they grow once they are given the space to grow

[sunshineband]

Taek the view that they are never going to get to full size in the tray, so in the ground they go 

[Paul Plots]

Taek the view that they are never going to get to full size in the tray, so in the ground they go 

Yep plant them... then keep them well watered until they seem to be holding their own.

I take out a drill and flood it with water. Once this has drained into the soil I use a dibber to make planting holes. (The moisture helps keep the planting hole stable instead of dusty dry soil falling in).
 
Next drop a leek into each and use the watering can to help wash soil into the holes onto the leek roots.
The advantage of the shallow drill is that the leeks are easier to water until they become established.

Good luck.