Fertilizer

This is the first time I have looked at rec.ponds, so my question is
probably well chewed already. I need recommendations about fertilizer
for Louisiana irises grown in water. I am a hybridizer and planning
to start a mail order business one day. I grow my irises in water in
half barrels in which olives, peppers and the like were imported. I
am familiar with fertilizing these irises in the ground, but unsure
what is best in this situation. A commercial grower I know who grows
Louisiana irises similarly just used Osmocote. Not sure of the
amounts or if this is really a good idea.

I would appreciate any insight or ideas on this. I think the irises
are hungry.

Patrick