I had planned to post earlier, but things have been so busy in gardens. We have been blessed to have many come through during Open House.
I often get asked what products I like to use on the irises. Here is a list that I have found works for me. I can say what I have found to be helpful. These products have been winners for me since the beginning.
Fertilizer - About six weeks prior to bloom, I treat the irises with bone meal or triple phosphate. In the past, I've used Hi-Yield Triple Phosphate and various brands of bone meal. I can't say the irises prefer one product over the other. Bone meal is typically less expensive. After the initial fertilizer treatment, I water the irises once a week with Scott's Super Bloom. I also do this six weeks after bloom.
Disease - Iris rot can be a big problem. You'll typically be able to tell if your iris has soft rot by looking and touching the rhizome. Soft rot makes the rhizome mushy and eventually the leaves will fall over. I like to scrape off the mushy area of the rhizome and treat it with a bleach/water mix. It's suggested to use 1 part bleach to 2 parts water. For leaf spot, I use Bonide Neem Oil. It may take more than one treatment. Additionally, the leaf should be trimmed below the last spot that you see on the leaf. If you continue to notice leaf spot going down the leaf, I would suggest removing the entire leaf.
Slugs/Borer - Prevention of iris borer is essential to maintaining a healthy garden. I like to use Cory's Slug and Snail Killer. I use this product in the spring and also periodically through July.