Pruning the spent flower stem of an orchid, particularly the common Phalaenopsis (moth orchid), is necessary once the blooms have fallen off. This redirects the plant’s energy away from maintaining the finished structure and toward vegetative growth or new flower production. Removing the old spike helps the orchid conserve resources needed to develop new leaves, roots, and a stronger future flower spike. This practice is essential for the orchid to remain healthy and rebloom successfully.
Identifying the Flower Spike and Nodes
The flower spike, or inflorescence, is the long, green stem that emerges from the base of the leaves and holds the blooms. This structure is distinct from the main body of the plant and is the part you prune after flowering. Along the spike are small, raised bumps called nodes.
Nodes are protected by a small, triangular flap of tissue known as a bract or sheath. They contain meristem cells capable of developing into new structures like a secondary flower spike, a leaf, or a small plantlet called a keiki. The location of these nodes determines where you make your cut, as they are points of potential new growth.
The Two Main Pruning Strategies
There are two main methods for cutting a spent Phalaenopsis spike, each serving a different goal for the plant’s immediate future.
High Cut Strategy
The “high cut” is used when the existing stem remains healthy and green. This technique involves cutting the spike about a half-inch above the second or third visible node from the base of the plant. This cut conserves the spike, encouraging the orchid to produce a secondary flower branch from the node below the cut. This method often results in a faster rebloom (eight to twelve weeks), but the resulting flowers are typically smaller and less numerous. This is suitable for vigorous, mature plants with stored energy.
Low Cut Strategy
The “low cut” is necessary when the flower spike has turned brown, yellow, or shriveled, indicating it is dead. The entire spike must be removed to prevent decay from traveling into the crown of the plant. The low cut is made about one inch above the leaves, close to the base. Removing the entire stem is preferred if you want the orchid to rest and focus energy on growing new leaves and roots. This allows the plant to gather strength, resulting in a stronger, new spike with larger flowers, though it means waiting longer for the next bloom (six to nine months).
Essential Tools and Technique
The precision and cleanliness of your tools are as important as the location of the cut. Use a sharp, sterile cutting instrument, such as a single-edged razor blade or sterilized pruning shears. Sterilization is performed by wiping the blades with rubbing alcohol or heating them briefly with a flame and allowing them to cool. This prevents the transmission of viral or fungal pathogens.
When cutting above a node, make a straight or slightly diagonal incision about a half-inch above the chosen node. Cutting diagonally helps prevent water from pooling on the wound, which can lead to infection. After cutting, seal the fresh wound on the remaining stem. Dabbing powdered cinnamon, which acts as a natural fungicide, onto the exposed cut surface protects the plant from disease.
Post-Pruning Care for Reblooming
Once pruning is complete, care shifts to encouraging a new flower spike. The most reliable way to initiate rebloom is to provide a specific environmental trigger, primarily a temperature differential. Phalaenopsis orchids often require several weeks of cooler nighttime temperatures (55 to 65 degrees Fahrenheit) while maintaining warmer daytime temperatures (70 to 75 degrees Fahrenheit).
Nutritional support is also important to build up energy reserves. After blooming, switch the fertilizer from a high-nitrogen blend (which supports leaf growth) to a balanced or high-phosphorus fertilizer. This change encourages the plant to focus resources on flower production rather than foliage. Continue to provide bright, indirect light, as insufficient light is a primary reason an orchid fails to rebloom.