They don't seem to mind a little shade. Here they tend to spread like mad, even in the cracks between the paving. Never had them fade away before. Try giving them a liquid feed when the flowers have gone over.

Thank you both. I have bought some bulbs and will try again in various places.

I have them under: a privet hedge, beech tree and Skimmia as well in an open aspect. They rarely fail to give a good show. The ground is quite damp in the spring and are happy in both situations. A feed may well be a good idea as Owd suggests.

Where you have them are they very in a very dry spot? That could be a reason for failure.

Hi SB, Well, I had them around the base of my amelanchier, which is in the middle of the lawn and I must admit it does get very dry in the hot summer weather. These 3 answers suggest various positions so I will scatter them around and make sure to feed them in the spring. I do love the blue ones. I don't remember them in any gardens from chijdhood days.

That would possibly be a very dry situation and have little food for them.
Our neighbour has the opposite problem. In his garden they are like weeds coming up all over the place in their hundreds.
They do seem to have only become more easily available over the last 20 years or so.
They have now been moved to Scilla by the way.
Dead easy from seed by the way, so if you get a seed set on them, sow when fresh and leave outside over winter for a spring germination. Flowering takes about 2 years.

PennyF if you want to put them where you feel it is a bit dry try mixing some moisture retaining granules in the soil. I have succeeded with some where plants that just wouldn't grow before.