I was just using bone meal at transplant & six weeks before bloom. I read it takes awhile to break down. At transplant I mixed it in the bottom of the hole, but tiny rhizomes let it be close enough to the surface to attract ground squirrels to dig them up to eat the bone meal. I tried various methods of capturing the squirrels and they are just too smart. In the end bubble yum gum was left out and the squirrel disappeared. I also broadcast the bone meal, but had to broadcast cayenne pepper to keep the neighborhood dogs from jumping in the bed to sniff around.
Last year was a departure where I decided to broadcast generic osmocote in the whole flower bed in addition. This slow release fertilizer seemed to make all my plants happy with the least amount of work on my part. Even the Dutch Iris decided to bloom again.
