frosts in may?

Worried that I may have been premature with planting out my bean seedlings, we took a trip down to the allotment yesterday to check on them, but all seems well. The rocket potatoes are doing well and the charlotte and maris piper are also poking through. The spring onion, beetroot and spinach seeds that I planted before Easter are slowly showing. Progress seems very slow- it can't be lack of rain so it must be the cold! But there is a hint of summer to come, with lots of flowers on the strawberry plants.