The message
from John contains these words:

This year, amongst a mixture of old and new daffodils, there are a
number of 'blind' plants.

Should these be thrown away or can they be persuaded to
flower next - and subsequent - years?

That depends on the cause of the blindness. It could be overcrowding,
or disease.

Good news: It's normal for daffodil bulbs to multiply underground, and
as the clumps become crowded, some of the smaller bulbs are so cramped
they can't ever grow to flowering size.They just produce leaves, and are
called blind. The leaves are healthy and green. It's cured by forking up
the whole clump around now, with the leaves still green, gently pull the
bulbs apart to separate them, and replant them all right away, at least
4 inches deep, well separated out. (Leaves will droop a bit and look
temporarily untidy, don't worry about that). Some clumps contain amazing
numbers of baby bulbs, a hundred or more. The fast way to replant large
numbers is by just pushing the spade into the soil and pull it back to
open a slit, dropping the separated bulb well down inside it, and
firming the slit shut with a fairly heavy tread of your foot so the bulb
isn't left sitting in an air pocket.No fertiliser is required. In future
seasons the small overcrowded bulbs will grow on to become flowering
size and in a couple of years you'll have a fabulous huge display.

Bad news: If leaves which are currently in full growth are partly
green but badly mottled with brown streaks and spots, the bulbs have a
disease which has permanently reduced their ability to flower and can
spread to other daffodils. Dig them up and burn them.

Janet.