Answer: Have they ever bloomed? If no, you may have a "bad" batch, a soil deficiency, or, they have been planted too deeply. It sounds like from your question they were blooming in the past, they stopped abruptly and you thought they simply needed divided. Then you divided them, and there is no improvement. Is this a correct assessment? I must admit I have never heard of daffodils just quitting like that. Usually, if there is a problem with their performance it is that they don't come up at allbecause of animals eating them, or, too deep planting. Additionally, some bulbs, like tulips, simply die out after a while, but daffodils naturalize and spread readily so you should have daffodils under construction all the time. In my area (I am in the same relative climate as you), we are still a few weeks away from daffodil blooms. If you don't see blooms by mid April, I would consider scrapping the lot of them. I can't explain why they behaved this way, sometimes nature baffles us.
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