[Flump]

I have some lettuce in a tray ready to plant out and some in a pot.The ones I have planted out seem to do okay ,then go soggy at the stem and wilt/die,same with some I put on the lottie.Am I over watering or something?

[sunshineband]

Do you plant them in too firmly and the leaf stems and growing point is getting crushed 

[Flump]

I don't know : / I didn't think so as the compost is so soft

[Kleftiwallah]

Sounds like it could be "Die Back".  Not Di Bach that Welsh bloke but I think it is a fungal disease.     Cheers,   Tony.

[SkipRat]

Try giving them less water, also when you plant them out is it possible that you are leaving a hollow for water to collect and maybe rotting them off ?