If they're already outside, could be they've been nipped in frost, or they're suffering from a bit of drought.

Or wind burn. We're having our fourth day in succession of very strong winds. Leaves and branches down all over the place. Are you having similar weather? It really strips moisture from plants. A good drying day is great for drying laundry, not good for new plants.

Thanks Bamboo and Beattie. I know it has been very dry but we have watered them every day but whether that is enough who knows. We have had strong winds so maybe it is a touch of frost or wind burn. Hopefully they will recover but thanks for your words of wisdom.