A Complete Analysis of the Key Cultivation Techniques for Sandersonia
Sandersonia (Sandersonia aurantiaca) is a bulbous flower of the lily family, named for its flower shape and color, which closely resemble Chinese palace lanterns. When in bloom, it looks like strings of lanterns hanging from the flower stems, set off by green leaves, and is extremely distinctive. Its English name is Christmas bells, because its flowering season falls at Christmas.
Growth habits
Sandersonia is native to South Africa, where the humid, rainy summer is its growing season and the dry, rainless winter is its dormant period. Because Sandersonia is not very demanding regarding temperature and sunlight, it is very well suited to greenhouse and field cultivation in temperate and subtropical regions.
The most suitable soil temperature for Sandersonia is 18°C-24°C, and it is best cultivated in a greenhouse with rain shelter and shading facilities. If the temperature is above 30°C, growth will be inhibited and the flower stems will become twisted. When planted in summer, high temperatures will shorten the growth period, causing flowering in less than 45 days, and the flower stems will also be shortened. Under normal conditions, Sandersonia flowers 60 days after planting. In northern Taiwan, China, or mid-altitude areas, the winter low-temperature period is longer and temperatures do not get too high to affect Sandersonia growth, so cut flower quality is good and bulb yield is high; in summer, however, the longer high-temperature period results in a shorter Sandersonia growth period, which is less favorable for cut flower and bulb production.
Propagation techniques
Sandersonia can be propagated by seed and by bulbs. After pollination, each flower stem of Sandersonia can bear 8-12 capsules, and each capsule contains about 50-70 seeds. Because the seeds have a deep dormancy mechanism, the germination rate is extremely low; treatment with gibberellin can increase the germination rate to 20%. After the seeds germinate, they grow through one growing season to form small bulbs of 1-2 grams, and the small bulbs then require another 1-2 years to develop into commercial bulbs for cut flower cultivation.
When Sandersonia is propagated from bulbs, each bulb has two growth points and can produce two new daughter bulbs. Bulbs produced in this way are larger, but the propagation rate is relatively low; during the growth and development of daughter bulbs, secondary bulbs often form, and these secondary bulbs readily detach from the daughter bulbs during digging or manual handling, causing the daughter bulbs to lose their growth points and sprouting ability. Because propagation from bulbs has a low multiplication rate, seed propagation is currently the main method for achieving large-scale production of high-quality bulbs.
Cultivation management
Soil and fertilization: Choose loose, fertile soil with good drainage. If the soil has low acidity, use quicklime to improve it, which can both improve the soil and kill some soil-borne pathogens and underground pests. If the soil is relatively alkaline, use phosphoric acid added to peat to improve it, with the amount depending on the specific situation. When preparing the land, broadcast fully decomposed organic fertilizer. Apply compound fertilizer at 375-600 kg/hm2 + organic fertilizer at 30000 kg/hm2 per mu, or other decomposed organic fertilizer, as a base fertilizer, and then mix it evenly into the top 30 cm of soil. In plots where other bulbous flowers have been grown, add 800-fold dicofol to prevent damage from root mites. Lilies do not require a very high nutrient level. Generally, no fertilizer is applied during the first three weeks of cultivation; during this period, ensuring good root development is most important. For relatively small bulbs, during the early growth stage when seedlings are 10-30 cm tall, spray fertilizer containing humic acid and some trace elements to increase stress resistance and promote rooting. Before the seedlings are 30 cm tall and before the stem roots have reached 5 cm in length, do not apply soil topdressing. After the stem roots emerge, apply calcium nitrate at 75 kg/hm2 once, or apply compound fertilizer at 150 kg/hm2 once. If nitrogen fertilizer is insufficient during the growing period and the plants often grow insufficiently sturdy, then apply quick-acting nitrogen fertilizer, generally at 20-150 kg/hm2. Soil topdressing is best done 2-3 times, and foliar topdressing can be done once a week. After topdressing, spray the plants once with clean water to prevent leaf burn.
Temperature management: Controlling soil temperature is the key to early-stage management. The most suitable soil temperature during the Sandersonia growing period is 18°C-24°C. During the first three weeks, or at least before the stem roots emerge, the temperature should be low. When the temperature is above 20°C, rooting quality will decline; especially in summer, keeping or promoting cool soil temperature is indispensable. If the daytime temperature is too high, plant height will be reduced, the number of flower buds per stem will decrease, and blind flowers will occur. If the nighttime temperature is below 15°C, it will cause bud drop and leaf yellowing, reducing ornamental value. In summer, cool the temperature through ventilation, misting, and shading; in winter, pay attention to heating and insulation.
Ventilation: In spring, summer, and autumn, temperatures are ensured, and midday temperatures are relatively high, so the greenhouse film and roof windows can be opened in the morning for ventilation, regulating humidity in a slightly cooler environment and avoiding sudden humidity changes during high-temperature periods; in winter, temperatures are low, so insulation measures should be taken, and air exchange must be carried out at noon when outside temperatures are high, with ventilation and air exchange done intermittently.
Light management: Insufficient light is unfavorable for flower bud formation, while excessively strong light can also affect cut flower quality. Generally speaking, during the growing period, shading treatment and supplemental lighting measures are needed to change the adverse effects of light factors on plant growth. Shading in the early growth stage helps increase plant height, especially in summer. Use shade nets inside, outside, and around the greenhouse to prevent the temperature inside from becoming too high and damaging the plants and flower buds. The period from flower bud differentiation to flower bud emergence is a sensitive period for leaf burn, so care should be taken that light and humidity changes are not too great.
Pest and disease control: Common diseases include gray mold, leaf spot, and root rot, mainly controlled through disinfection of bulbs and soil. If disease occurs during the growing period, alternately spray fungicides such as amobam and carbendazim at regular intervals of 7-10 days. Common pests are mainly underground pests such as root mites and aphids, controlled with phoxim and dicofol.
Cut flower harvesting: When the lowest 3 flowers on the flower stem have fully opened and turned golden yellow, the cut flowers can be harvested. Usually, after cutting, leave 2-3 leaves at the base of the plant. The harvested cut flowers should be placed in clean water promptly to absorb water for more than 2 hours, then placed in preservation solution and kept in a low-temperature cold storage room at 6°C-8°C. After 4-6 hours, they are graded and packaged.