Last year my daffodils were touched I think with a severe frost, other ABs had the same problem and the daffs didn't flower. I've noticed, though the daffs have come through fine again this year, there are very few flower heads. Does this mean they need replacing for next year. What are your experiences?
I would give them one more year. Bulbs tend to travel upwards over the years and soil gets washed away from on top of them. Give them a good feed this year and a thick mulch of compost or bark chippings....anything that will insulate them in the cold weather and break down to enrich the soil.
Yes, they have a habit of going blind if they are no longer deep enough. But they will flower for years and years if happy. There are daffs in this garden that have flowered for decades, though, of course, some may new bulbs that have seeded or divided ! And they are within close proximity to a constant, annual, deposit of leaves and hence leaf mould.
I had no flowers on my daffs last year. Left them alone, and they're back to doing fine again this year, with plenty of flower buds (poking up through the snow!).