Calla lilies (Zantedeschia) are popular ornamental plants known for their elegant, spathe-like flowers and glossy, often arrow-shaped foliage. Maintaining their health requires regular attention through targeted pruning and sanitation. Proper technique ensures the plant directs its energy toward producing new blooms and strengthening its underground storage structure, the rhizome. Understanding precisely when and how to make these cuts is fundamental to a successful growing season and preparing the plant for dormancy.
Removing Spent Flowers (Deadheading)
The most frequent pruning activity during the growing season is deadheading, the removal of spent flowers. Once a flower’s decorative spathe begins to fade, turn brown, or collapse, it should be removed to redirect the plant’s available resources. Allowing a flower to mature enables the plant to invest significant energy into seed production, which directly diverts resources away from rhizome growth and subsequent blooms.
The correct technique involves following the flower stem, or peduncle, down to its point of origin near the base of the plant. A clean cut should be made as close to the rhizome as possible, rather than simply snapping off the flower head. This deep cut prevents the remaining hollow stem from collecting water, which could lead to rot and potentially introduce pathogens to the storage organ below.
Trimming Yellowed or Damaged Foliage
Foliage maintenance involves removing leaves that become physically damaged, spotted with disease, or naturally begin to yellow during active growth. It is beneficial to wait until the leaf is significantly discolored before removal, as the plant actively reclaims mobile nutrients from the leaf tissue. This process, called senescence, allows the plant to efficiently recycle resources back into the rhizome for storage.
Prematurely removing a partially yellowed leaf wastes this valuable stored energy, forcing the plant to spend more resources creating new photosynthesizing tissue. Once a leaf has turned mostly yellow or brown, it has finished transferring its stored energy and can be removed. The leaf stem should be traced back to the base of the plant and severed cleanly near the soil line, similar to the deadheading process, which improves the plant’s appearance and airflow.
Cutting Back for Dormancy
Preparing calla lilies for their dormant period requires seasonal pruning that differs significantly from ongoing maintenance cuts. This process begins when the plant signals the end of its active growth cycle, typically in late fall or early winter, or after the first light frost. The entire stand of foliage must be allowed to completely yellow and collapse naturally before any cuts are made.
This complete dieback ensures the rhizome successfully withdraws all remaining energy and nutrients from the leaves, maximizing its reserves for the next season. Premature cutting prevents this energy transfer and can significantly weaken the plant’s ability to produce robust growth and flowering the following spring. Once the foliage is completely withered and brown, all remaining plant material should be cut back severely.
The stems are typically severed one to two inches above the soil line, leaving only short stubs visible. In cooler climates, this cutback is necessary before the rhizomes are dug up, cured, and stored for winter protection. If the plants are left in the ground in warmer regions, trimming provides a neat appearance and prevents disease from overwintering in decaying matter. Potted calla lilies can be cut back and the container moved to a protected, dark area for storage, or the rhizomes can be removed and stored individually.
Essential Pruning Tools and Sanitation
Pruning requires using sharp, clean cutting implements, such as bypass pruners or scissors, to ensure clean cuts that heal quickly. Dull tools crush or tear the stem tissue, leaving ragged wounds more susceptible to infection by fungi or bacteria. Tool sanitation is important to prevent the transfer of pathogens between plants.
Tools should be wiped down with a disinfectant, such as 70% isopropyl alcohol or a 10% bleach solution (one part bleach to nine parts water), both before and immediately after use. This procedure minimizes the risk of spreading infections throughout the garden.