Iris are susceptible to botrytis crown rot and gray mold Before planting, soak rhizomes along with 3-4” of leaf base in a disinfecting solution for 30 minutes to help prevent rot.
1 gallon water,
1 ½ teaspoons Consan 20
Most irises need to be planted in the full sun in order to Siberian iris can tolerate light shade.
Iris prefer a light, nutrient rich soil. If soil is heavy clay, work organic material into the top 8-10” before planting. Bone meal and/or garden fertilizer (low in nitrogen) are good for irises. Manure can be worked into the soil also, but make sure that it is well composted; otherwise, it may cause rot. Fertilize regularly with a low nitrogen fertilizer to keep your iris healthy.
Irises can spread quickly and will need to be divided every 2-3 Late July or August is usually the best time for dividing. Water well after transplanting.
Iris should be planted with the roots deep enough to hold plant in place but shallow enough that the rhizome is near the surface. If the rhizome is planted too deep, it is likely to rot.
If planting several irises, plant them at least a foot and a half apart. Plant the iris so that the leaves all fan out in the same direction- this will allow the rhizomes to increase in the same direction without crowding each other out too quickly.
Water immediately after planting and fertilize with Root Stimulator to encourage new root