Onion seedling question.

[poozie]

I just bought 3 trays of white onion seedlings for 45p each from my local nursery. How close should I plant them together? And also will they need protecting from frost?

[Demeter]

Any idea what variety they are? I believe the planting distance is normally about 4 inches - more if you want bigger onions, less if you plan to harvest them early / small. I imagine if you've just bought them, it's because they are overwintering onions and should not therefore need much or any protection.