How to plant marigolds: A detailed explanation of marigold cultivation techniques

How to plant marigoldsIf you want to know how to plant marigolds and the detailed cultivation techniques of marigolds, the following is a comprehensive introduction.Marigolds, also known as stinking cosmos, marigold lamps, and golden daisies, are annual herbs of the Compositae family, native to Mexico and Central America in North America. They were introduced to China in the 16th century and have been widely cultivated and domesticated, with a distribution across the country. Marigolds have a long blooming period and beautiful flowers, making them ideal for decorating flower beds and landscaping. Depending on their height and size, they are commonly used for decoration in different occasions. Shorter varieties are mostly used for flower beds, flower paths, and flower clusters, and can also be potted for indoor or courtyard placement. Taller varieties can be used as fresh cut flowers or for park landscaping. In addition to this, marigolds also have good edible and medicinal value and are a famous dish in the flower cuisine. Researchers have conducted extensive research on the chemical components and pharmacological effects of marigolds, and have found that their extracts have antioxidant, antitumor, anti-cardiovascular disease, and immune-boosting effects. In recent years, with the continuous deepening of research on artificial cultivation, researchers have bred many varieties of marigolds, with the most common ones being Antigua, Inca, and wrinkled-petal.1. Growth habitsMarigolds have sturdy and upright stems, with a plant height of 0.5-1.5 meters. They are mainly distributed in areas with altitudes of 1,100-1,500 meters, with wild ones often found on the edges of ditches or meadows at the foot of mountains. Marigolds are heliophilous plants that prefer to grow in environments with sufficient sunlight, temperatures of 15-25°C, and humidity of around 65%. The plants are robust with bright flowers, with the optimal blooming temperature being around 20°C. Insufficient light will cause the stems and leaves to become thin and soft, reducing flowering. Growth is extremely slow when the environmental temperature is below 10°C, and it will stop growing below 5°C. When the temperature is above 30°C, the plants will grow excessively, reducing or not flowering at all. They are not picky about soil and can grow in slightly acidic, slightly alkaline, and various soil types, but the best conditions are fertile, well-drained loamy soil.2. Propagation methods2.1 Seed propagationIn the northern regions, spring sowing can be done around April. Before sowing, soak the seeds in 40°C warm water for 3-4 hours to promote germination, then remove the seeds and sow them. The seeds germinate best in a shaded environment. After sowing the seeds on a prepared seedbed, cover them with a 0.5 cm layer of soil, then water to keep the seedbed moist. To prevent the seedbed from drying out, cover it with grass mulch and water it every day to maintain moisture. Seedlings will emerge in about a week. When the seedlings grow to 5 cm tall, transplant them once, and when they have 7-8 true leaves, they can be planted. Additionally, sowing can be done in the summer, generally from June to July. After summer sowing, it is necessary to control the environmental temperature to prevent excessive seedling growth due to high temperatures. Seedlings will bloom 2 months after sowing.2.2 Cutting propagationMarigold cuttings are generally done in the summer, as the high temperatures promote faster root growth. Select the current year's tender branches from the mother plant, cut them into插穗 about 10 cm long, remove the leaves, and soak the lower ends in rooting powder solution before inserting them into sandy soil. Then water thoroughly, cover with shade netting, and water daily. Roots will start to grow in about 2 weeks, after which they can be transplanted or left to bloom in 1 month if not transplanted.3. Cultivation management3.1 Land preparation and fertilizationChoose a sandy loam soil with loose texture and deep soil layer for transplanting. One month before sowing, deeply plow the land to a depth of 25 cm and apply base fertilizer, supplemented by nitrogen, phosphorus, and potassium fertilizers depending on the soil fertility. After plowing, remove stones, wooden stakes, and other debris from the plot, then level the land.3.2 TransplantingWhen the marigold seedlings reach a height of about 20 cm and have 3-4 pairs of true leaves, they can be transplanted. Use wide and narrow row交叉种植 with wide row spacing of 65-70 cm and narrow row spacing of 45-50 cm, and a plant spacing of 25-30 cm. In the northern regions, plastic mulch can be used for planting to increase soil temperature and promote flowering. After transplanting, water thoroughly to help the plants adapt and grow.3.3 Management after transplantingFirst, earth up. After transplanting, when the plant height reaches 25-30 cm and starts to branch, gradually grow a few branches. At this time, earth up while weeding to promote the growth of adventitious roots and make the plants stronger. The soil from between the rows can be used for earthing up around the base of the plants. Second, top pruning. To promote thicker stems, reduce nutrient consumption, increase flowering, and improve flowering quality, top pruning can be done when the plant height is greater than 30 cm. Third, water management. Water appropriately based on soil dryness, with the best condition being slightly dry and slightly wet soil. Avoid excessive watering that floods the planting ridges. Fourth, fertilization. Fertilize before flowering and during the full bloom period, applying a small amount of nitrogen, phosphorus, and potassium fertilizers and micro-fertilizers each time. Foliar application can also be done by spraying urea and potassium dihydrogen phosphate solutions on the leaves to promote absorption.3.4 Harvesting and preservationFor fresh-cut marigolds, preservation measures must be taken after harvesting to extend the flowering period and maintain the flowering effect. The timing of cutting is crucial; avoid cutting too early or too late. Cutting too early will cause the flower heads to droop and not open properly; cutting too late will cause the flower buds to open prematurely and reduce the flowering period. It is best to cut when 4-6 petals of the flower bud are loose, about 1-2 days before flowering. When cutting, leave enough length on the stem, with each stem having at least 5 internodes and 2 buds. Cutting should be done in a low temperature and high humidity environment. After cutting, place the stems in water for 30-60 minutes to absorb water, then bundle them in groups of 10-15 and store them in a temperature of 1-2°C, or immerse the lower ends in water for low-temperature storage to extend storage time.4. Pot cultivationSince marigolds have a relatively low height, they are also very suitable for pot cultivation, used for home planting. Pot cultivation can be done directly by sowing, choosing loose peat soil and sandy soil as the matrix. Mix a small amount of organic fertilizer into the soil when potting, press the soil surface slightly, water thoroughly, then scatter the seeds in the pot, cover with a thin layer of soil, and place in an environment with a temperature of 20-25°C. Seedlings will emerge in about a week.5. Diseases and pests and their controlMarigolds are prone to many diseases and pests. The main diseases include powdery mildew, black spot, and leaf blight, while the main pests include scale insects, aphids, caterpillars, spider mites, and beetles. Proper disease and pest control is crucial for promoting normal growth and improving flowering quality of marigolds.5.1 Powdery mildewThis disease usually occurs in plots with high humidity, insufficient light, and poor ventilation, mainly infecting the tender leaves of marigolds, occasionally seen on stems, and visible on flower buds during flowering. The early symptoms are not obvious, but careful observation can reveal white powdery substances on both sides of the tender leaves. Symptoms usually worsen after 3-5 days, with leaves becoming waterlogged, turning yellow, and eventually drying up and falling off, affecting flowering. This can be controlled by spraying fungicides such as benomyl wettable powder 1,000 times, or 20% triazole ketone emulsion 1,500-2,000 times, or 50% methyl thiophanate wettable powder diluted 1,000 times. Apply every 7-10 days for 2-3 times.5.2 Black spotMarigold black spot, also known as leaf spot disease, is caused by the fungal pathogen Septoria chrysanthemi. This disease is a significant one in marigold cultivation, spreading quickly and causing severe damage. It can occur at any growth stage, mainly infecting leaves and tender shoots. Strong branches are rarely infected. If not controlled in time, large irregular black-brown spots will form on the leaf surface, causing the leaves to turn yellow, black, and eventually dry up and fall off, affecting normal plant growth and development. Control measures include proper cultivation management, reasonable fertilization and watering, avoiding continuous cropping, avoiding dense planting, ensuring good ventilation, and promptly removing and burning diseased leaves or plants. Before sowing, make sure to disinfect the seeds. During cultivation, if the disease occurs, spray with 25% propiconazole emulsion 600 times, or benomyl 800-1,000 times, or 50% mancozeb wettable powder 500 times, or 10% Bordeaux mixture, spraying every 7-10 days for 2-3 times.5.3 Leaf blightThe pathogen of this disease is the half-known fungus Alternaria tenuis, which mainly invades from the leaves, usually entering from the leaf tip or margin. Initially, small yellow or brown spots appear on the leaf tip or margin and quickly spread inward, forming irregular large spots on the leaves, causing the leaves to turn yellow, become light brown or gray-white, and eventually dry up and fall off. Control measures include comprehensive control, first strengthening water and fertilizer management to improve plant resistance; second, promptly cutting and destroying diseased plants and spraying fungicides. Additionally, chemical control can be done by spraying 0.5 degree Baumé lime sulfur solution on the planting area ground in early spring; during the peak incidence period from July to August, use 75% chlorothalonil wettable powder 800 times, or 70% methyl thiophanate wettable powder 1,000 times for spraying control, every 7-10 days for 2-3 times.5.4 Scale insectsScale insects mainly absorb the sap of marigold tender stems and leaves, causing poor plant growth. They are most likely to occur in high temperature and high humidity environments with poor ventilation and low light. Control measures include spraying 25% pyridaben wettable powder 2,000 times during the peak hatching period of nymphs.5.5 AphidsAphids, mainly including marigold pipe aphids and peach aphids, can occur at any stage of marigold growth. They mainly harm tender stems, leaves, and flower buds, severely affecting plant growth and flowering. Control measures include observing and controlling aphids in time, using 10% imidacloprid wettable powder 2,000-4,000 times for spraying.5.6 CaterpillarsCaterpillars mainly occur in high-temperature seasons, with both larvae and adults harming marigolds. Adult caterpillars are about 15-16 mm long and come in many species, with the main ones harming marigolds being yellow caterpillars, green caterpillars with brown edges, and flat caterpillars. Control methods include biological control, protecting natural enemies such as the ichneumon fly and mantis; using light traps to kill adults; chemical control with 25% chlorpyrifos suspension concentrate 1,500-2,000 times during the third instar of larvae, or 2.5% decis悬浮剂 1,500-2,000 times, or 20% pyrethroid emulsion 1,000-1,500 times for control. Severely affected branches and leaves can be removed and destroyed, or larvae can be manually captured.5.7 Spider mitesBoth adult mites, nymphs, and larvae can cause harm to marigolds, usually聚集 on the back of leaves to absorb leaf flesh. The highest incidence occurs in high temperature and dry environments. Control methods include biological methods such as protecting and releasing natural enemies like the phytoseiid mite; reasonable fertilization, avoiding excessive nitrogen fertilizer, and weeding. Physical methods include removing plants affected by mites before pupation and removing old and damaged leaves, then burning them. Chemical methods include spraying 25% bialaphos wettable powder 2,000 times during the adult stage, and abamectin or dinotefuran during the larval stage. For indoor cultivation, neonicotinoid insecticides can be used.The above is the full content on how to plant marigolds and a detailed explanation of marigold cultivation techniques, hoping to help green plant enthusiasts!