Phalaenopsis Flower Forcing Techniques and Analysis of Key Points

In order to supply Phalaenopsis potted flowers to the market during New Year's Day and the Spring Festival, the Rizhao City

Landscape Bureau and the Rizhao City Agricultural High-Tech Demonstration Park in Shandong Province conducted 3 years of research on Phalaenopsis flower forcing technology

and systematically summarized a set of technical regulations.

Production facility

An improved solar greenhouse is used, equipped with fan coil heating, fan wet curtain, and external

shading for cooling and humidification, and other necessary temperature and humidity control equipment.

Technical measures

Temperature control

(1) Day-night temperature: during the vegetative growth period, the daytime temperature is controlled between 26°C and 28°C,

with a maximum not exceeding 32°C; the nighttime temperature is controlled between 20°C and 23°C, with a minimum not lower than 15°C.

(2) High-temperature treatment: carried out 1 month before the low-temperature treatment, with a daytime temperature of 28°C to 30°C,

a nighttime temperature of 20°C to 23°C, combined with enhanced lighting, to promote nutrient accumulation in the plants so that they can better

transition to reproductive growth.

(3) Low-temperature treatment: carried out 4 to 5 months before the planned flowering period, with the daytime temperature lowered

to 25°C and the nighttime temperature lowered to 18°C. At this temperature, Phalaenopsis shifts from vegetative growth to

reproductive growth and begins to form flower buds, lasting 1 to 1.5 months, completing the entire process of flower bud formation.

When the flower stalk grows to about 10 cm, the low-temperature treatment is ended. If the low-temperature treatment is extended,

the flowering period will be delayed; if it is ended too early, the emerging flower stalk will grow thin and weak,

so the timing of the low-temperature treatment must be well controlled.

(4) Temperature treatment during the flower stalk elongation and flower bud development period: the day-night temperature is (25°C

to 28°C)/(18°C to 20°C). In this temperature environment, the flower stalk can be made thick and strong,

the flower buds develop quickly and become plump, and the flower color is good. When the stalk emerges and the flower buds appear, special attention must be paid to temperature

changes, which must not be too fast, otherwise bud drop is likely to occur. During flowering, the day-night temperature can be lowered

to 25°C/18°C.

Humidity control

Relative humidity should generally be controlled at 60% to 80%. Too much humidity makes disease infection likely;

too little humidity is unfavorable for orchid growth. When greenhouse ventilation is good, the daytime relative

humidity is about 70% and the nighttime humidity is about 80%, which is beneficial for the rapid growth of Phalaenopsis.

(1) Methods to increase greenhouse humidity: a. Except for the walkway, do not make the floor concrete;

a mud surface or a sand-and-gravel surface is better; b. spray or irrigate water onto the ground; c. mist to humidify.

(2) Methods to reduce humidity: a. natural ventilation or forced ventilation; b. increase temperature to reduce

humidity.

(3) It should be noted that a large amount of water should not be poured into the pots to increase humidity, as

doing so very easily causes root rot; humidity changes in the greenhouse should also not be too rapid, otherwise bud

drop is likely to occur.

Light control

Phalaenopsis has strict light requirements; light must not be too strong or too weak. Too strong easily causes

sunscald, with mild cases suffering tissue damage and leaves turning yellow, and severe cases turning grayish white and triggering

anthracnose; too weak light reduces photosynthetic capacity, causing leaves to grow leggy, weak, and

drooping, which is unfavorable for flower bud differentiation and results in fewer flowers. Generally, the light intensity is 15000 to 20000 lux.

During the high-temperature treatment before flower forcing, the light should be slightly increased to 20000 to 25000 lux, so that the seedlings

accumulate more nutrients and better transition from vegetative growth to reproductive growth, and the forced flowers are also

more uniform with better quality.

Water and fertilizer control

Cultivating Phalaenopsis requires applying an appropriate amount of fertilizer at the appropriate time. For medium-sized Phalaenopsis seedlings,

generally a 2000-fold dilution of compound fertilizer with N:P:K of 20:20:20 is applied; before flower forcing,

1 to 2 applications of high-phosphorus fertilizer are needed, a 2000-fold dilution of compound fertilizer with N:P:K of 9:45:15;

after the flower stalk emerges, apply a 2000-fold dilution of compound fertilizer with N:P:K of 10:30:20;

when the flower stalk grows to about 10 cm, spray a 2000-fold dilution of compound

fertilizer with N:P:K of 30:10:10; when the flower buds develop into flowers, stop fertilizing. The relationship between water and fertilizer is 2 times

fertilizer to 1 time water. Orchids prefer dryness and dislike wetness; water only when dry, and when watering, water thoroughly.

When it is found that root tips show yellowing or that new roots shrink back and cannot extend once they touch the surface of the water moss,

first observe whether it is due to too much water or fertilizer burn, and then according to the situation carry out water cutoff or

leaching treatment. EC value and pH value should be measured the day after fertilizing. The suitable pH value is 5.5 to 6.5,

and the EC value should be lower than 1.6 mS/cm. Fertilizer concentration should not be too high; apply light fertilizer frequently.