My husband comes from the Pacific Northwest and LOVES Miracle-Gro. It took me a few years to get him used to the idea of NOT putting it on my Iris! Iris do not like Miracle-Gro.
Here's a little Fertilizer/Chemistry lesson for today.
No... stop that, I hate Chemistry, but I love my iris. &:-)
When you buy fertilizer for your garden/flowers, there are usually some numbers on the side of the box or bag that look like 10-10-10, or 24-8-16, etc... some are balanced and some are not. Also on the box/bag there are other numbers (if you can't find the three number sequence) under a title called GUARANTEED ANALYSIS.
This is a breakdown of the major 'ingredients' of your fertilizer. Let's use our Miracle-Gro example. It says 24-8-16 on my box. This means that it is 24% Nitrogen
(this is the first chemical on the list under Guaranteed Analysis) It looks like this:
Total Nitrogen (N).....................................24%
3.5% Ammoniacal Nitrogen
20.5% Urea Nitrogen
Avaliable Phosphate (P2O5).....................8%
Soluble Potash (K2O)..............................16%
This is where we get our three number sequence 24-8-16
Now, Nitrogen is pretty commonly called Nitrogen.
Phosphate is also called Phosphorus, which is what Iris love. If you visit any Iris web-sites, don't become confused... ask me how I know.. ha ha! Phosphorus is Phosphate and vice-versa.
Potash is Potassium, but is usually called Potash.. I thought I'd throw that out there just in case.
Ok, the Chemistry lesson is over.
The reason why Iris do not like Miracle-gro, is because it is high in Nitrogen. You'll get tons of leaves but your rhizomes will be susceptible to bacterial soft rot during warm weather. I can promise you that more Iris are lost to rotted roots than anything else. Another cause of root rot is over watering. Iris like to be dry.
Phosphorus can promote strong roots, solid rhizomes and strong and plentiful bloom stalks.
When buying fertilizer for my Iris, I buy a balanced, slow release one, like the 10-10-10, and I also apply Triple Super Phosphate in the early spring,( This one is 0-45-0 ) and work it in into the ground about 4-6 inches away from the center of the plant. When planting a new rhizome, I work in a few handfuls of bonemeal. This contains Phosphorus too.
