Calamansi, often recognized as the Philippine lime or Calamondin orange, is a tropical citrus hybrid prized for its small, tart fruit. This plant, scientifically known as Citrofortunella microcarpa, is a compact evergreen tree originating from Southeast Asia. While commercial growers often use grafting to ensure fruit quality and accelerate production, cultivating Calamansi from seed offers a rewarding experience. This method requires considerable patience, as the tree will take several years to mature.
Preparing Calamansi Seeds for Planting
Proper seed selection and immediate preparation are essential, as citrus seeds quickly lose viability once dry. Select fresh, plump seeds extracted from fully ripe fruit, which typically contain several seeds each. After extraction, the seeds must be thoroughly cleaned to remove all traces of the gelatinous pulp surrounding them.
The pulp contains germination inhibitors and sugars, which can lead to mold and fungal growth. A quick rinse under running water, followed by a gentle rub between paper towels, is sufficient to clean the seed coat. To give the seed a head start, soak the cleaned seeds in water for about three days, changing the water daily. Viable seeds will sink; discard any that float.
Calamansi is known to be polyembryonic, meaning a single seed can produce multiple seedlings that are genetically identical clones of the mother tree, a beneficial trait for growing true-to-type citrus. Planting the seeds immediately after cleaning is paramount to capitalizing on the high moisture content required for the seed to sprout. Unlike some other seeds, Calamansi generally does not require a cold stratification period to break dormancy.
Sowing Seeds and Encouraging Germination
Calamansi seeds require a sterile, well-draining planting medium to prevent “damping off,” a common fungal disease that kills young seedlings. A mixture of half peat moss and half perlite or coarse sand provides the ideal texture, offering aeration while retaining moisture. The soil pH should be slightly acidic, ideally ranging between 5.5 and 6.5, mimicking the Calamansi’s native conditions.
Sow the seeds shallowly, planting them only about one-half inch deep in small pots or seed trays that have adequate drainage holes. Consistent warmth is a primary requirement for successful sprouting, with soil temperatures needing to remain in the tropical range of 70°F to 85°F. To maintain the high humidity and warmth that citrus seeds prefer, you can cover the container with clear plastic wrap or a dome, creating a miniature greenhouse effect.
Place the covered containers in a location that receives bright, indirect light, avoiding direct, intense sun, which can overheat the soil and scorch the emerging seedlings. The soil should be kept consistently moist but never waterlogged. Under these conditions, successful germination can be expected to occur within two to six weeks.
Nurturing Seedlings and Long-Term Care
Once a seedling emerges and the first true leaves develop, the plastic covering should be removed to allow for increased airflow and prevent disease. This young plant must then be slowly transitioned, or “hardened off,” to accept more direct sunlight, eventually needing a minimum of six to ten hours of bright light daily for robust growth. When the seedling reaches about four to six inches in height and has developed a stable root system, it is time to transplant it into a larger container, such as a four- to six-inch pot.
When transplanting, you must handle the roots with extreme care to minimize disturbance, which can cause shock to the young plant. For long-term growth, the Calamansi will need a larger container, ideally one that is at least 18 inches in diameter, to accommodate its root network. Young citrus trees are considered “heavy feeders” and require regular fertilization to support their continuous growth cycle.
During the active growing season, apply a balanced, slow-release fertilizer that is high in nitrogen, such as ammonium sulfate or urea, every few months. As the tree matures and the goal shifts toward fruiting, switch to a complete fertilizer that includes phosphorus and potassium. Growing Calamansi from seed is a multi-year commitment, with the tree typically taking between four and seven years to produce its first crop of fruit. If you reside in a non-tropical climate, the plant must be brought indoors during the winter when temperatures consistently fall below 54°F (12°C). Indoor care requires placing the tree near a sunny window and providing supplemental humidity until the warmer outdoor growing season returns.