I'd like to get some input on the group here on when it's best to
water and fertilize established bulbs (bulbs that have grown and
bloomed for at least one year). I understand it makes sense to add a
little fertilizer and water to a new bulb planting.

My particular bulbs are daffodils and bearded iris. Technically
bearded iris isn't a bulb, but I suppose this could apply to any
perennial.

I've read arguments that go both ways.

One says don't water or fertilize in the fall because plants go
dormant then, and the added fertilizer might encourage the plant to
stay active, and the added moisture might cause the dormant bulb to
rot. So it should be done in the spring as soon as new growth starts.

I've heard arguments that say that once a bulb starts growing in the
spring, it will not absorb any water or fertilizer applied to it at
that point and for the rest of the season, so it should be done in the
fall.

I've read that most bulbs (tulips, daffodils, etc.) are members of the
lily family and originate in mountainous areas of the mediterranean.
There they are only active in the wet spring, then go dormant for dry
summers and freezing winters. The Dutch/German hybrids that are
available today have inherited this behavior.

So it seems to me that if the bulb is dormant in the fall, it wouldn't
make sense to fertilize until very early spring, say April 1.

What do you think?