No flowers here either.
Last Friday night, I think, we were threatened with 3/4 degrees... and I am always wary in the spring of a just above zero night, have been caught out before. We are just north of London, quite rural and exposed here, so temps drop fast. I didn't happen though. Think the day time temperatures are still high enough that even if drops to 3 or so, it's just not cold enough to form a frost.
I have some sheets of membrane, which we recently used to cover an old flower bed before gravelling. It's fairly tough stuff, so would probably hold off a mild frost. Last May I was really badly caught out, put some plastic sheets over my news, but the sheet was touching the leaves, I didn't have it raised up enough and boy, some were soooo badly bitten. I was utterly 
. Thought I had lost a number of my plants, but they bounced back. This time of year though, if they get bitten, not much chance to bounce back, so if I need to cover, will do much more carefully and make sure sheeting does not touch if going to be a proper frost. The plastic sheeting got used for something else, so the membrane is the next best thing I have.