When to Cut Dead Mum Stalks
Mums (Dendranthema spp.) survive outdoors as perennials in U.S. Department of Agriculture plant hardiness zones 5 to 9, although individual species, hybrids and cultivars might have narrower potential growing ranges, and mums are often cultivated as annuals. Hundreds of selections offer a range of growth habits and diverse flower colors, shapes and other characteristics. Pruning mums appropriately encourages attractive, disease-free plants.
The appropriate time to cut dead mum stalks back to the ground depends mostly on a gardener's personal preference, although other factors should be taken into consideration. Mums respond well to pruning back in late fall once flowering has ceased or a frost or freeze has caused dieback or in spring just before new growth begins to emerge.
In places where a mum species or cultivar is marginally hardy, leaving the dead stalks intact until spring offers slight protection from cold temperatures. If the mum stems and leaves are affected by a pest or fungus, cutting the mum back in fall might help to limit the pest or disease presence the following year. However, pruning in fall can also leave the cut stalks and plant crown exposed to more moisture, potentially leading to problems with crown rot.
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