How to Cut Down Daylily Plants. After the flowering period, the plant begins to prepare for winter. But I do gently pull off the dead stems in the early early spring (mid late March) from the last year's blooms. And during the spring summer years, I pull off the the iris leaves that turn a … Let the foliage yellow and die down naturally. The sword-shaped leaves and tall graceful flowers of an iris (Iris spp.) Bee balm (Monarda) and phlox (Phlox paniculata) with powdery mildew are examples. Iris plants are generally cut back in autumn. Dividing Irises in the Fall. It is OK to cut back the leaves any time after they begin to yellow or become limp. After hard frost in the fall, cut foliage back hard, remove any foliage that appears spotted or yellowed and dispose of all debris in the trash. Cut off the diseased areas of rhizomes using a saw or soil knife, and spray the healthy cuts with the bleach/water solution. ... By fall, it can become cover for iris borers and fungal diseases. Cut back plants with disease or insect pest problems to reduce the chance of infection the following season. Even resistant varieties of bee balm and phlox can become infected in bad weather so cut them all back. Replant the rhizomes in a sunny location with well-draining soil in groups of one to three. Cutting back perennials in the fall is often necessary to keep the plant healthy. Daylily pruning is simple. I never cut back my irises during the fall, I just let them grow naturally. Many are the garden plants that need hard pruning before the cold begins, this is not the case of the iris. Cutting the foliage to ground level is fine if the foliage dies back completely, but avoid cutting into the exposed tops of the rhizomes. Irises bloom for a short period of time in early summer, then the leaves remain until fall to collect nutrients for next years blooming. Irises are a tubular or bulb. The scapes, which are the stalks or stems the flowers bloom on, can be cut back right at the base with pruning shears. These 34 perennial plants are best cut back during this season. The … So much for regular bearded irises blooming in the fall, but there are also iris cultivars that naturally rebloom, that is to say, irises that bloom as usual in the spring, then a second time at the end of the season (August, September or October, depending on the local climate). Avoid removing any of the foliage until it is completely died back or until … How to Trim Iris Leaves After Blooming. When the plant is in bloom and green growth stage all the nutrients for the bulb is in the top part of the plant. If iris foliage is hit with heavy frost, … Cut back the foliage of both bearded and Siberian irises to within 6 inches of the ground. The bearded iris (Iris germanica) grows as a perennial in U.S. Department of Agriculture plant hardiness zones 4 to 10. It is advisable to leave the foliage on this plant. Advertisement. Perennials to cut back. plant provide an anchor in garden beds and borders. Using pruners, cut the foliage down by half. Just avoid cutting back the entire plant until late fall or early spring. 4.2 Cutting back iris after bloom (in fall) for winter. As the green starts to die off, the nutrients are returned back in to the bulb for next seasons growth. Alternatively, you can wait until a tug on the scape dislodges it easily. The leaves can be left to die back naturally at the end of the growing season, or they can be cut back when crisp, freezing weather is in the forecast.