When to apply which Fertilizer
Last spring I moved to a new house in Indiana and created a large raised bed. In the middle of the lawn there was a huge mass of iris rhizomes that the neighbors told me hadn't bloomed in years. I transplanted about 40 of them to the new bed and last August planted a number of dark variety irises I bought from Schreiner's (Before the Storm, Anvil of Darkness, Midnight Oil, etc.
I've read that I should apply a superphosphate or 6-10-10 about six weeks before bloom, but new to growing irises, I don't know when to expect blooms in this zone (5B-6A). Any advice on approximately when I should apply a fertilizer? Also, any thoughts on which fertilizer would be best would be greatly appreciated.