Calendula, also known as Calendula, belongs to the genus Calendula in Compositae. Marigold is the most common herbaceous flower in gardens and cities in early spring, with short plants, dense flowers, bright colors and long flowering period. Marigold originated in Europe and has been cultivated there for a long time. It is widely used in small family gardens and potted plants. Marigold is one of the protagonists in early spring, appearing in planting troughs and sporadic corner flower beds on both sides of urban streets. Due to the continuous emergence of new species and varieties of flowers, the status of marigold has declined slightly. However, there are still many new varieties of marigold. Today, Thomson Morgan Company in Britain and Qi Dan Jay Flower Company in Israel are famous in Europe for their marigold breeding and production, and their new varieties have been cultivated all over the world. Marigold cultivation in China was introduced from abroad after18th century, and then potted marigold appeared. During the Qianlong period of the Qing Dynasty, a large number of marigold flowers were produced in the suburbs of Shanghai. After the founding of New China, marigold was widely cultivated in gardens, used for potted viewing and flower bed arrangement. After 1980s, the double-petal, big-flowered and dwarf marigold was introduced into China, and the marigold took on a brand-new look, and now it has become one of the important herbaceous flowers in China. Morphological characteristics and varieties: calendula is a biennial herb. The whole plant is hairy. Leaves alternate and oblong. The flower head is solitary, with a flower diameter of about 5 cm. There are yellow, orange, orange red, white and other colors, as well as double petals, rolled petals, green hearts and deep purple flower hearts. The common varieties are BonBon, with a plant height of 30 cm, compact flowers, a flower diameter of 5-7 cm, and colors such as yellow, apricot and orange. FiestaGitana, plant height 25-30cm, early flowering, double petals, flower diameter 5cm, and colors are yellow, orange and bicolor. Kabulauna (Kablouna) series, with plant height of 50 cm, large flower species and colors of gold, orange, lemon yellow and apricot yellow. , the flower center is dark, in which 1998 new rice lemon Kablau (KablounaLemonCream) is a beige tongue-shaped flower with a lemon yellow center. TouchofRed, plant height 40-45cm, double petals, flower diameter 6cm. The colors are red, yellow and red/yellow, and the top of each tongue-shaped flower is red. Gemstone series, plant height 30 cm, double petals, flower diameter 6-7 cm, colors are lemon yellow and golden yellow. DwarfGem is more famous. In addition, Shengri guitar is a short variety with large flowers and double petals, with a flower diameter of 8 ~ 10 cm. Xiangrui, a very short species, has strong branching ability, large flowers, double petals and a flower diameter of 7 ~ 8 cm. And the lemon queen and OrangeKing. Biological characteristics: marigold is native to southern Europe and the Mediterranean coast. Cold-resistant, afraid of heat, like sunny environment. The suitable temperature for the growth of calendula is 7 ~ 20℃, the seedlings can tolerate the low temperature of -9℃ in winter, and the suitable temperature for the adult plants is 0℃. If the temperature is too low, it needs to be protected by film, otherwise the leaves will be easily frozen. When the temperature is above 10℃ in winter, calendula grows white. In summer, the temperature rises, the stems and leaves grow vigorously, the flowers become smaller and the petals decrease obviously. Marigold seedlings should be slightly wet, which is beneficial to the growth of stems and leaves and improves the cold resistance in winter. Adult plants should be slightly dry, which can control the growth of stems and leaves to avoid excessive growth. Indoor or shed cultivation, air humidity should not be too high, otherwise it is easy to get sick. Ventilation should be strengthened to adjust indoor humidity. Calendula likes plenty of sunshine, especially when it is cultivated in the open field or greenhouse in winter, which is very beneficial to the growth of stems and leaves, and the seedlings grow short and orderly. If there is too much rain and snow and insufficient light, the basal leaves will turn yellow easily and even the roots will rot and die. The soil should be fertile, loose and well-drained sandy loam or cultivated land. The optimum pH value of soil is 6 ~ 7. In this way, plants have many branches and big flowers. Propagation method: calendula is propagated mainly by sowing. Sow in greenhouse in autumn or early spring, with one gram 100 ~ 125 grains. The optimum temperature for germination is 20 ~ 22℃, and the soil sown in pot should be disinfected. After sowing, cover the soil for 3 mm and germinate in about 7 ~ 10 days. The seed germination rate is 80% ~ 85%, and the seed germination period is 2 ~ 3 years. Cultivation management: the seedlings are transplanted once when there are 3 true leaves, and planted in a pot of 10 ~ 12 cm when there are 5 ~ 6 true leaves. 7 ~ 10 days after planting, coring to promote branching or spraying 0.4% Bijiu solution 1 ~ 2 times on leaves to control plant height. Fertilize 1 time every half month during the growth period, or use Huiyou 20-20-20 general fertilizer. With sufficient fertilizer, marigold blooms in large numbers. On the contrary, the fertilizer is insufficient, and the flowers are obviously smaller and degraded. No seeds are left in the flowering period, and the withered flowers are cut off, which is conducive to the germination of flower branches, more flowers and longer flowering period. To preserve seeds, choose plants with bright flowers and pure varieties, and collect seeds on sunny days to prevent them from falling off. Pest control: If marigold is cultivated indoors, it often suffers from Fusarium wilt and downy mildew due to poor ventilation and high humidity. Spraying 500 times of 65% zineb wettable powder can prevent and control it. When the temperature rises in early summer, it is often found that the leaves of calendula are damaged by rust, so it is sprayed with 2000 times of 50% Weixiuling wettable powder. Early spring flowering is vulnerable to red spiders and aphids, and 40% omethoate EC 1000 times can be sprayed. Postpartum treatment: Calendula has bright yellow flowers and green leaves, which are very eye-catching. Potted plants are placed in central squares, railway stations, shopping malls and other public places. Shining in the sun, it presents a magnificent scene. A few pots adorn the windowsill or balcony, and the golden flowers of marigold make the room brighter and more comfortable. Of course, planting a long round leaf and a round flower on the campus of kindergartens and primary schools is also the best material for children to sketch. Potted marigold can also be stored indoors to supply the market all year round. The initial flowering period of marigold can be kept in good condition for more than 30 days at 65438 00℃ and 7500 lux light. Calendula marigold seedlings can be made by watering them first, and storing them under the illumination of 1. 1 ~ 4.4℃ and 14 hours every day, and keeping them intact for 15 days.