How to grow dahlias? An introduction to dahlia care and management
Dahlias are world-famous flowers, known for their many varieties, rich colors and strong vitality. There are now more than 30,000 dahlia varieties, making it one of the species with the most flower varieties in the world. There are 11 common types of dahlias, such as Shouguang, Zhaoyang, Liren and so on. Dahlias have a great many names honoring their flower colors and forms, and are rich and varied, making them one of the world's famous flowers. Dahlias are loved for their magnificent colors and beautiful blooms; Mexicans regard them as a symbol of generosity and richness, and therefore honor them as the national flower. The theme flower of the 12th Shanghai (International) Flower Show was also the dahlia. So how should dahlias be grown? How can you grow dahlias that bring great fortune and prosperity? Today Huacao Le shares with you the knowledge of dahlia care and management.
How to grow dahlias? An introduction to dahlia care and management
1. Planting dahlias
Dahlias like loose, humus-rich, well-drained sandy loam. The usual soil mix for growing them is 5 parts garden soil, 2 parts leaf mold, 2 parts sandy soil and 1 part cake fertilizer. Loosen the soil promptly in routine management and drain any standing water from the pot.
2. Fertilizing dahlias
Dahlias like fertilizer; starting from the seedling stage, generally apply 1 dilute liquid fertilizer every 10-15 days. After flower buds appear, apply 1 time every 7-10 days, and stop fertilizing once the buds show color. They can grow well at pH 6.7-7.8. The amount of fertilizer depends on the plant's growth. Pale, thin leaves indicate a lack of fertilizer; scorched leaf edges or yellowing leaf tips indicate too much fertilizer; thick, deep green leaves show that fertilizing is just right. To make the stems thick, the concentration of the fertilizer should be increased each time.
3. Watering dahlias
Watering should follow the principle of "water thoroughly once the soil is dry." Dahlias like water but fear waterlogging, because dahlias have fleshy tuberous roots and too much watering easily rots the roots. Since dahlias have lush branches and leaves, they use a fair amount of water. For watering dahlias, generally in the early growth stage of small seedlings, the water requirement is limited; on sunny days, water once a day, keeping the soil mound slightly moist, as both too dry and too wet are unsuitable. In the later growth stage, with lush branches and leaves, water consumption is greater; on sunny days or days with north winds, note that water shortage easily occurs at noon or in the evening, so watering should be appropriately increased.
4. Temperature and light for dahlias
Dahlias are not strict about temperature and can grow normally between 5-35°C, but 10-25°C is most suitable. Dahlias like light and cannot tolerate shade; if kept in a shaded place for a long time, they grow poorly, with weak roots, thin leaves and slender stems, small and pale flowers, and some may even fail to bloom. Therefore, potted dahlias should be placed in a spot with plenty of sunlight. During leaf growth, they need sufficient light, requiring more than 6 hours of light per day, so that the plants are sturdy and the flowers large and full. If daily sunlight is less than 4 hours, stem and leaf branching and flower bud formation will be affected to some extent; especially with cloudy, rainy weather and little light, flowering will be poor, stems and leaves will grow poorly, and they are prone to disease.
5. Shaping and pruning dahlias
To grow dahlias with medium and small flowers, only remove the side buds on several nodes of the lower stem so that they bloom successively. To grow a large single flower, keep only the top bud and remove all other side buds. At the end of June and beginning of July, after the first flowering, the weather gradually gets hotter and plant growth slows, so pruning can be done at this time. When pruning, first twist the stem in the middle of the branch, between two leaves, and bend it downward, leaving a height of 20-30 cm. After a few days, once the wound has dried and shrunk, cut it. This can prevent rainwater from pouring into the hollow stem and causing rot. Grown until October, it can bloom again.
6. Regulating the flowering period of dahlias
Dahlias have gorgeous flower colors, with large, eye-catching, brightly colored flowers standing above emerald green branches and leaves; potted plants arranged into flower beds of various shapes can better show a sense of group beauty, so they are often a key decorative flower for beautification and greening at National Day. So how can dahlias be made to bloom around National Day as scheduled? After the first cutting of flowers in early July, renewal pruning can be carried out. First twist and break the branch to be cut, leaving a height of about 20 cm, and cut it off after it wilts, to prevent rainwater from pouring in through the hollow stem and causing rot. After cutting, watering should be appropriately controlled, and soon new shoots will sprout from the base of the stem. If you want to grow a single-stem dahlia, remove all side buds once the new shoot has grown to a certain height, leaving only the main branch. After growing this way for more than two months, it can again form buds and bloom, meeting the need for flowers at National Day.
7. Pest and disease control for dahlias
(1) Powdery mildew: harms leaves, tender stems, flower buds and other parts. In the early stage of the disease, spray 70% thiophanate 800-1000 times solution for control.
(2) Gray mold: during the plum rain season or continuous rainy weather, tender shoots, young leaves and flower buds and other parts develop brown or dark brown rot and become covered with a gray mold layer. After the disease occurs, remove the affected parts and spray 50% zineb 800-1000 times solution.
(3) Bacterial wilt: a bacterial disease that infects the aboveground parts and tuberous roots; in hot, humid weather with high soil moisture content, this disease is likely to occur. Before planting, sterilize the soil with 1% formalin, or after the disease occurs, promptly remove the diseased plants and spray 70% fenaminosulf 600-1000 times solution.
(4) Viral disease: spread by virus-carrying insects, grafting and sap; spray promptly to kill the virus-transmitting insects.
(5) Dahlia stem borer moth: the larvae bite and eat dahlia leaves, stems and flower centers; after growing larger, they bore into the stems and cause damage, and in severe cases the whole plant dies. Before the larvae bore in, they can be caught by hand, and 50% fenitrothion 100 times solution can be sprayed; after the larvae have bored into the stem, inject 30%-50% dichlorvos emulsion.