When to Cut Frozen and Damaged Foliage?

Plant Types

• Woody plants, such as trees and shrubs, tend to have more cold-resiliency compared to soft-tissue herbaceous types. However, the plant species and its native origins also determine how much damage occurs after a freeze. An herbaceous, temperate-zoned plant species may survive a freeze much better than a woody, tropical shrub exposed to the same cold temperatures. Woody plants first shed leaves and flowers, but the woody stems persist and may survive. Herbaceous plants sustain death to leaves and stems, often killed back to the ground. A plant's underground roots may escape harm from the freeze.
  
  

Damage Time Frame

• Depending on the plant species and below freezing temperature, damage may occur immediately or as much as 30 days later. Initial damage may show up as wilted or browned/scalded leaves that may or may not drop off the stems and branches. Over the next few weeks, damaged plant cells dry out. While initial damage may only be wilted leaves, the upper stems can also dry out and brown slowly. Ultimately, not until spring or after the threat of frost has passed, will the freeze-damaged plant reveal if any living roots, stems or buds remain to grow the plant anew.
  
  

Pruning Insight

• Wait at least one week, after the freeze, before evaluating the plant for damage. This allows the plant to naturally dry out and reveal its immediate dead tissues for you to evaluate. Any slimy, rotting tissues can be pruned away as this may produce a fungal or rot problem later. Also cut off any tissues that smell like sulfur -- an indication of decomposition. Do not cut away any leaves or stems that are still green, even if they're ugly. The green tissues photosynthesize light and help the plant recuperate. Delay extensive pruning for 30 days after the freeze or in spring when frosts/freezes are no longer likely.
  
  

Benefit of Waiting

• Leaving frost-damaged tissues on a plant the duration of winter acts as a buffering insulation against cold. Further nights of frost and freeze first affect the already killed tissues, rather than quickly reaching any underlying living tissues. Once temperatures warm up to promote new growth, the plant naturally sprouts new buds to reveal what roots, stems or branches are still alive. Once you seen where the new growth is emerging, you can prune off the dry, dead parts without mistakenly cutting off dormant but living parts.