[rowlandwells]

I've lost a couple labels from 2 seed trays I think there leek seed coming up but not sure how can you tell which is onions or leeks ?

[Hampshire Hog]

What about squeezing a shoot you should find the onion has a characteristic smell.
Can’t think of any other certain method when they are small, although I have noticed that my very few onion seedlings seem to flop over more than the leeks.
Good luck HH

[rowlandwells]

maybe I need to wait till the plants get a bit bigger HH what I intend to do is take them out the modules and put them in a row down the allotments then as they get bigger I should be able to see if there onions or leeks? maybe that's the best way ?

[Rob the rake]

As the seedlings develop you'll be able to see from the multiplying leaves whether they're one or t'other. Leek seedlings develop flat leaves, whereas the onion leaves remain tubular.