Are the blueberry bushes in pots or planted in the garden? If in the former, I was told to take care about over- watering and about under -watering.

I have just the one bush planted in the garden and last year I picked quite a lot of blueberries which I froze. Don't know why I bother really as Trehayne's is around the corner and two years ago we went a bit mad and picked so many blueberries on their PYO site that we still have some in the freezers.

At the moment there isn't a single leaf on the bush but plenty of buds.

The birds appreciate their take away as the blueberry is planted right next to their source of water!

We have acidic soil and when there is a drough water with tap water.

I'd echo that question - are they in pots or in the ground? Are they in separate parts of the garden?

Blueberries will deplete the nutrients very quickly. They are very hungry & thirsty plants. If they are in pots, you may consider a complete soil change before they wake up. Prune out the old canes. That will also be a good opportunity to inspect the root system for unwanted critters, nematodes, parasites, roundworms, etc.