Too much Nitrogen. Simply sprinkle around some Triple Phosphate.

In article , Mother Mastiff\
wrote:

Last year the iris bed (about 3 years old now and new corms added each year)
bloomed PROFUSELY. I put some rotted chicken manure in their bed in late
summer and mulched with pine straw. There was nly space to add two new
corms.

This spring I was excited because of the big lovely bluish green leaves (the
bed finally looked mature somehow, or close to full), but only two plants
(out of over 30) bloomed. I kept looking excitedly for the buds, but --
nothing!

What did I do wrong? If the chicken manure had too much nitrogen, what can
I do now to balance things out?