teeny carrot seedlings

I have planted 2 row up at the allotment but had some started in a plastic greenhouse (as didn't think we would be getting llotment until May or so).

The seedlings are only about 1cm high and have been outside every day, can I just leave them outside whilst I go on my holibobs? as the plastic greenhouse is in full sun and even a daily water from the neighbour might not be enough?