Flowers are the most wonderful plants in nature. Because of their existence, people's lives are more colorful. The technology of flowering period regulation has long been mastered. There is a record of Wu Zetian blooming the "untimely flower" peony. Nowadays, it is not difficult to make flowers bloom at a fixed time according to people's wishes outside the natural flowering period, that is, the so-called "urging hundreds of flowers to bloom in a moment and gathering four seasons in one time". Making flowers bloom earlier than the natural flowering period is called forced cultivation, and delaying the flowering period is called inhibition cultivation. The main technologies for regulating flowering period are: temperature control and flower control method, light control and flower control method, day and night reversal treatment method, shading and extending flowering time treatment method, sowing period regulation and flower control method, water and fertilizer control and flower control method, gas regulation and flower control method, pruning and flower control method, and drug control and flower control method. The flowering period regulation techniques used by different flowers are not exactly the same.   

The duration of light exposure affects the growth and development of flowers. The duration of sunlight required for the differentiation of flower buds of various flowers is different. Controlling the duration of light exposure by artificial methods can achieve the purpose of controlling the flowering period. For long-day flowers, in order to make them bloom in the autumn and winter when the natural daylight is short, they can be placed under the light for 3-4 hours after sunset and heated appropriately. For short-day flowers, that is, flowers whose flower buds must be less than 12 hours of light to differentiate, more shading for several hours and reducing their light exposure time can delay their flowering period. Generally, in the evening or morning, cover with black cloth or black plastic bags, shade for several hours, and only give 8-10 hours of sunlight a day, and it will bloom in about 2 months. On the contrary, if the light exposure is increased by several hours artificially to more than 12 hours a day, the purpose of delaying flowering can be achieved. Some flowers and plants in nature cannot adapt to strong sunlight, especially when they are in bud, proper shading or moving the plants to a place with weaker light can prolong the flowering time. If you expose a blooming azalea to the scorching sun for a few hours, it will wilt; but if you place it in a semi-shaded environment, the blooming time of each flower will be greatly extended. For flowers that adapt to strong light, such as peonies, roses, and carnations, if you properly shade them during the flowering period, the ornamental life of each flower can be extended by 1 to 3 days. Therefore, during the flowering period of flowers and plants, if you want to extend its ornamental period, do not let the sun shine directly on the flowers and keep the temperature as low as possible.

The beautiful Epiphyllum blooms at night. To make it bloom during the day, after the buds appear, you can shade it during the day and artificially supplement light at night. Gladiolus is a long-day flower that needs more than 14 hours of light a day. According to this feature, the quality of the flowers can be improved by regulating the time the gladiolus receives light every day through shading. In winter, if you increase the light appropriately, it will be beneficial for the flowers to bloom; in summer, you can use a sunshade net to shade and lower the temperature to improve the quality of the flowers. For large-flowered varieties, you can delay their flowering by lowering the temperature. Any variety of gladiolus can delay flowering by shortening the light to within 10-12 hours a day. Chrysanthemum is a short-day flower that is very sensitive to the number of hours of light. By increasing the light or shading, chrysanthemums can bloom at any time of the year. If you start to supplement light with lights in early September and stop artificial auxiliary lighting in early and mid-November, chrysanthemums can bloom before the Spring Festival. However, the light bulb used must be placed 1 meter above the top of the chrysanthemum. The effective illumination area of ​​a 100-watt light bulb is 4 square meters. If chrysanthemums and poinsettias are placed in the dark from 5 pm to 8 am the next day, poinsettias will bloom after more than 40 days of treatment, and chrysanthemums will bloom after 50-70 days. However, plants treated with short-day light must grow strong and have a height of 30 cm. Stop applying nitrogen fertilizer before treatment and increase the application of phosphorus and potassium fertilizers.

 The crab orchid is a common indoor flower in the United States during Christmas. It is a short-day plant. If you want it to bud and bloom, it must be treated with short-day light so that the buds can form. If you put the crab orchid in a place you don't often go to at night, such as by the window of the laundry room, cover it with a large cardboard box at 4 or 5 o'clock every afternoon, or put it in the closet at night and take it out early the next morning. In short, let it see the light for no more than 10 hours a day. After 2 months, there will be a small bud at the tip of each leaf, that is, the modified stem. When the buds of each leaf are formed, stop shading and take it to a bright place. Around Christmas, it will bloom. To make the bracts of Christmas red change color, you should also treat it in this way. To make the Kalanchoe bud and bloom, you must also control the light, that is, give it 8-9 hours of light every day, and put it in the dark for the rest of the time. It will bud and bloom after 3-4 weeks. In the long-day season, you can cover it with black cloth or black paper to keep the sunshine time below 10 hours, which can promote its flowering, but you need to stop applying nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer. If you want to prolong the flowering time, you can keep the sunshine time for more than 10 hours, or use light to supplement the light.

The flowering of flowers and trees depends on the differentiation of internal flower buds and external temperature. The flower buds of peach blossoms, crabapples, bauhinia, plum blossoms, forsythia, lilac, winter jasmine, peonies, azaleas, etc., have mostly completed their differentiation before the beginning of winter, and are forced to dormant as the temperature drops. As long as the temperature is properly adjusted, that is, heating to accelerate germination, their flowering period can be controlled so that they can bloom during Christmas and New Year. If there are potted plants of these flowers at home, the flower pots can be placed on the windowsill of a sunny room and placed about 1 meter away from the heater at night; or a transparent plastic film cover can be buckled on the flowers and trees that need to be heated, but a narrow gap should be left at the contact with the pot soil for ventilation. The film cover can be removed at night, so that these flowers can bloom during the holidays. However, the flower stems of some flowers need to be pre-treated with a certain low temperature before their flower stems can be elongated and bloom, such as hyacinths, tulips, Clivia, daffodils, freesias, bulbous irises, and musk lilies. To ensure that tulips can bloom on time, the daytime temperature should be kept at 17-20℃ and the nighttime temperature at 10-12℃ during the growing season. When the temperature is high, the temperature can be lowered by shading and ventilation. When the temperature is too low, the growth can be promoted by heating and increasing the light. For example, if the temperature of fuchsia is lowered, it can be promoted to bloom continuously. Due to the corresponding low temperature induction, the differentiation of its flower buds can break the routine, that is, dormancy is broken in advance, flower buds are formed and the development of flower buds is accelerated, and flowering is early. Otherwise, flowering can be delayed.

Plum blossoms are very sensitive to temperature, and their flowering period is easy to control. If you want plum blossoms to bloom during the Spring Festival, you can move the flower pots to a sunny place indoors one month before the Spring Festival, keep the temperature above 10°C, but not too high, and spray water on the branches frequently, and you can enjoy the flowers during the Spring Festival. If you want plum blossoms to bloom in early May, you can place the plum pots full of flower buds in a cold room slightly above 0°C at the beginning of the year, and gradually move them outdoors in mid-April. Regarding potted daffodils, if the room temperature is maintained at around 5°C, it will take 50-60 days to bloom; if the room temperature is maintained at 10°-15°C, it will bloom in 35-45 days; when the room temperature is above 18°C, it will bloom around 30 days. If you move the daffodils into a greenhouse above 15°C 1-2 weeks before they are expected to bloom, and use lights to heat and supplement light day and night, you can also make the daffodils bloom early.

　  In order to break the dormancy of bulbous flowers and flowers and trees and promote early flowering, drugs are often used; mainly gibberellins (GA) drugs, to promote flower bud differentiation and increase flowers. For example, if 0.05% to 0.1% solution of gibberellins is applied to the buds of camellia sasanqua, magnolia, camellia, Michelia, and peony, camellia sasanqua and magnolia can bloom 1 to 2 months earlier, camellia can bloom 2 to 3 months earlier, Michelia can bloom 3 to 4 months earlier, and peony can bloom 5 to 6 months earlier. Spray red sage with 0.002% solution of gibberellins, and new inflorescences can be drawn after 4 to 5 days. Gibberellins can also inhibit flowering, and can promote flowering for a few short-day flowers such as chrysanthemums and impatiens. If gibberellins are used to drip the growth points many times, short-day chrysanthemums can bloom. All potted flowers and trees that use drugs to adjust the flowering period must grow strong, and the maintenance measures such as water and fertilizer are appropriate. Attention should also be paid to timely and appropriate ventilation. When the bulbs of bulbous flowers are treated with low temperatures, the humidity must be controlled. Excessive humidity can cause disease and premature sprouting. The less water content in the bulbs, the earlier the flower buds differentiate. This is the case for bulbs such as tulips, hyacinths, and lilies.

 By sowing to adjust the propagation period or planting period, pruning, pinching, fertilizing and controlling water can also effectively adjust the flowering period. For example, if the branches of roses are cut short immediately after their flowers fade, new branches can sprout and bloom after about 45 days if the conditions of water and fertilizer are suitable. If ivory red is pruned immediately after each flower fades, it can bloom 3-4 times a year. If crape myrtle is lightly pruned during its flowering period, it can bloom again after about 45 days. Pinching can also delay the flowering period of flowers, such as petunias, dianthus, Dutch chrysanthemums, and saffron. Pinching can promote side branches, which can not only increase the number of flowers, but also delay or extend the flowering time. Jasmine can be treated by leaf removal to promote the growth of new branches, and the flowering period can be postponed by 10-15 days.

The flowering period can also be adjusted by reducing nitrogen fertilizer, controlling watering, and increasing phosphorus fertilizer to achieve the purpose of changing the flowering period. If drought can also be used to control the flowering period, because many flowers enter a dormant state during the drought season, the robust and substantial tissues will differentiate flower buds, and will promote flowering after the flowers wake up. Therefore, artificial dormancy is performed on the longevity flower. 20 days before it blooms, it is placed at 40°C, watering is stopped, and old leaves are removed. After 3-5 days, it is placed in a cool place and watered in an appropriate amount, so that the flowers can pass the dormant period and continue to grow and bloom. Using drought treatment can also make flowers such as Magnolia grandiflora bloom again. In the flowering period control treatment stage, the type and amount of fertilizer applied should be controlled, less or no nitrogen fertilizer should be applied, and phosphorus and potassium fertilizers should be applied as the main ones. Too much nitrogen fertilizer affects flower bud differentiation, and can only shoot and grow leaves without blooming, thereby causing failure of flower control. Cyclamen is a fertilizer-loving plant. Nitrogen, phosphorus and potassium fertilizers should be used in a balanced manner during its growth period. More potassium fertilizers should be applied during the bud formation period, and concentrated fertilizers should be avoided. Nitrogen fertilizers should not be applied during the flowering period, otherwise it will cause the branches and leaves to grow too long and shorten the life of the flowers.

Many flower growers have their own special experience in regulating the flowering period. For example, they believe that the early or late flowering period of osmanthus is closely related to the early or late cooling after the beginning of autumn. Generally, if the temperature drops early in autumn, the flowering period will be advanced; if the temperature drops late, the flowering period will be delayed. Usually, after the temperature drops in autumn, intermittent rainy and wet weather is a prerequisite for the early flowering of osmanthus. Cooling is related to rainfall. After rainfall, the temperature drops and the relative humidity of the air increases. Such microclimate conditions are more conducive to the blooming of osmanthus buds. For ground-planted osmanthus trees, the lowest temperature is below 17°C for more than 4 days, and the highest temperature is above 26°C for several days, accompanied by rainfall, and osmanthus can bloom. However, potted osmanthus trees can bloom after 14-16 days under the temperature conditions of 13-16°C. If you want to make osmanthus bloom earlier, just move the potted osmanthus indoors, subject it to low temperature, and increase the relative humidity of the air; if you want to delay flowering, reduce the temperature difference between day and night in its growth environment, so that it will not be affected by low temperature, and maintain a low relative humidity of the air to delay the development process of osmanthus flower buds, so as to achieve the expected flowering purpose.