In article ,
Andrew May wrote:

Assuming they still produce healthy leaves, non flowering could be
caused by overcrowding / starvation.. especially if you planted them too
shallow.Daffodils vary considerably in how how much hardship they will
tolerate.. some types are almosr indesctructible and others relatively
shortlived.

I doubt that they were planted too shallow. I took the opportunity of
relaying the lawn to dig out a deep area, probably about a spade depth,
scattered the bulbs at the bottom and refilled before sowing grass on top.

I did wonder whether they might have been rotting because it can get
quite damp down there. But then suddenly all of these pop up.

Another cause can be cutting the tops off too early. I believe
that, surprisingly, fertilising them too much can also cause that
by enabling the grass to out-compete the daffodils.


Regards,
Nick Maclaren.