water them well and give them a dilute feed. leave foliage on for as long as possible. if you can wait until the top 3rd of the leaves are yellow that will give your bulbs the best chance of them forming flowers.

Follows SBG's advice you can use half strength tomato food to feed them. Bulba and I let the leaves die back completely to ensure the maximum amount of energy goes back to the bulb to help with flowering next year. Oh and leave the bulbs in the ground don't dig them up!

Sometimes they grow blind if the clumps are overgrown, I find that splitting large clumps of bulbs helps them start to flower. (lift divide and re-plant after they have died down) Bulbaholic is one to advise on bulbs etc. he knows how to do things with bulbs very knowledgeable.

This has been a common problem this spring and some suggest it is because the very dry spring last year prevented them from taking up enough nourishment to produce flower buds. Give them a good liquid and make sure they don't dry out. Do not cut off or tie up the leaves, but let them die down naturally.