Now that the blooms of my tall bearded iris (iris Germanica) are over should I cut down the stem to the ground or just half way?
It’s common practice to remove the blooms and stalks after blooming has completely finished. Cut the flower stalks right down to the foliage. This will allow the plant to devote its energy into growth rather than going to seed. Removing old blooms and stalks also encourages repeat flowering next season. Let the leaves die back naturally. They are a source of energy for next years growth. When the leaves go brown they will pull away easily. Damaged leaves should be removed by cutting or pulling off. This will help control disease.
Iris rhizomes multiply rapidly and may require dividing every 2-5 years. Divide after plants have finished blooming, in late summer or early fall, for best results. Cut the leaves to about 1/3rd of their height. Newly planted irises may need to be mulched for winter protection. If you follow these tips your irises should bloom for many years to come.