[iwantanallotment]

Should they be punctured for drainage?

Haven't done mine, because I only water sparingly....but should they be?

Apologies if this is mentioned elsewhere.....I did search, but soooo many posts 

This is my first time with leeks in cat litter trays, and so far I'm really impressed with the results. Thank you, DD 

[DD.]

Yes - make drainage holes. You may water sparingly, but  the things you sow may need to go outside sometime.

Rain may not be quite so sparing.

Holes are best make with a red hot skewer or similar. Don't try to push something like a screwdriver through the bottom, the plastic will crack.

[BobandJack]

Use a drill with a fine bit, by far the easiest way to do it, just put a bit of scrap wood underneath so you don't damage the drill bit or the kitchen table etc.