A terminal spike is a flower stem that emerges directly from the center, or crown, of the orchid’s main growth axis, most commonly observed in Phalaenopsis (Moth Orchids). This event signals a permanent end to the growth of new leaves from that central point. Once the terminal spike develops, it consumes the meristematic tissue responsible for producing new foliage, meaning the main plant stem will never grow upward or produce new leaves again. While the orchid is not immediately dying, this development marks the end of its vegetative lifespan in its current form, compelling the plant to adopt a different strategy for survival.
Identifying the Growth Point
Distinguishing a terminal spike from a normal flower spike is important, as their locations are fundamentally different. A typical, lateral flower spike emerges from a node on the side of the main stem, appearing from the sheath at the base of a leaf. This lateral growth does not interfere with the central crown, allowing the plant to continue producing new leaves.
A terminal spike, conversely, erupts directly from the very center of the orchid’s canopy, where the newest leaf would ordinarily emerge. Its growth consumes the apical meristem, the plant’s primary growth point for leaves. Visually, a healthy new leaf starts as a smooth, folded spear. A terminal spike often presents with a pointed, sometimes reddish or purplish, “mitten-shaped” tip, positioned to cut right through the heart of the foliage.
Physiological Triggers
The shift in growth strategy that results in a terminal spike is a complex response involving hormonal signals and environmental stress. Orchid growth is governed by the balance between auxins, which promote vegetative growth, and cytokinins, which stimulate cell division and flowering. A disruption in this balance, potentially triggered by external factors, can cause the apical meristem to differentiate into a flower spike instead of a leaf.
Several environmental factors are considered contributing elements, especially in Phalaenopsis hybrids. Extreme or sudden temperature fluctuations, particularly a sharp drop, are known to induce flowering. If the plant is also under stress from inadequate care or low light, the spike may deviate into the central crown. Genetic predisposition in certain hybrids may also increase the likelihood of this growth anomaly.
Survival Through New Growth
Although the main stem’s leaf production has ceased, the orchid has a built-in survival mechanism to propagate itself. The plant channels its remaining energy into producing entirely new growths, ensuring the continuation of its genetic line. These new plants, which are clones of the mother, primarily manifest in two distinct forms: basal growths and keikis.
Basal growths are new plant stems that emerge from the base of the mother plant, near the roots or along the main stem below the terminal spike. These growths develop their own root systems and eventually become independent, full-sized plants. The orchid may produce aerial plantlets called keikis (Hawaiian for “baby”) directly along the nodes of the flower spike itself. A keiki must remain attached until it develops its own healthy root system, typically with at least three roots that are three inches long, allowing it to be safely separated and potted.
Care After Termination
Once a terminal spike is confirmed, the grower’s focus must shift from promoting the mother plant’s central growth to supporting these new clonal growths. Change the fertilization routine, moving away from a high-phosphorus “bloom booster” formula to a balanced growth formula, such as a 20-20-20 ratio, to support vegetative development. Maximize the plant’s overall health by ensuring optimal humidity, aiming for a range of 50 to 70 percent, and providing bright, indirect light.
The terminal flower spike should not be cut immediately after the blooms fade. It serves as a source of energy and a potential site for a keiki, allowing the plant to naturally draw back remaining nutrients. After the spike has completely yellowed and dried, it can be removed with a sterilized cutting tool near the base of the plant. The sole focus then becomes maintaining the health of the basal growths or developing keikis.