Do iris need mulch during the growing season?
No. Covering the rhizomes with soil or organic materials at this time promotes rhizome rot. What about dividing iris? Healthy iris plants should be divided every third or fourth year. The rhizomes branch like a fork and grow outward from the back of the fan of leaves. Dig the plants with a spading fork and gently pull apart the divisions. Cut back the foliage to about six inches. Examine the rhizomes carefully for signs of problems, such as rot or borers, keeping only healthy rhizomes. Generally the vigorous portions are the younger parts of the clump. Place the rhizomes on top of a ridge of soil and spread out the roots. Cover with soil making sure the rhizome is partially exposed. When the soil has been firmed and the plant watered, the rhizome should be half-exposed out of the soil. What care do they require in fall? After a killing frost, remove all the foliage from your irises. Since iris borer is a problem in our area, there has been a lot of discussion about whether or not to mu
