Detailed Explanation of the Key Technical Points for Cultivating and Managing Impatiens walleriana
In the application of herbaceous flowers in Europe and America, Impatiens walleriana ranks first. It offers a broad range of brilliant colors and grows vigorously with simple management. It is suitable for tray and container cultivation, hanging baskets, flower walls, window boxes and balcony planting. A germination rate of over 90% in plug trays has meant that impatiens have consistently outperformed other series varieties in all plug tray quality parameters, flowering earliest, with the richest colors and free branching. The plants are covered with large masses of flowers, creating a superb flowerbed and flower border display, with a plant height of 20-25 cm. The colors of the leaves and flowers are extremely vivid and richly varied, with more than 40 colors in total. Against a shaded background in the garden, the colors harmonize, well-proportioned and delicate, enriching and adding depth of tone to the flower display.
Cultivation and Management
The potting soil should be a loose, fertile sandy loam. It is even better to use 1/2 peat soil or leaf mold mixed with 1/2 sandy loam plus some decomposed cake fertilizer powder or commercially available chicken manure. Such soil is loose and fertile, more suitable for plant growth, and also favorable for the root growth of young plants. At the 2-leaf stage of the seedlings, they can first be pricked out once, and when they are about 4 cm tall, they are planted into flower pots. When planting, it is best to choose a cool, humid environment for placement, to help the seedlings recover and survive, and also to promote earlier flowering. After the plants have established and survived, they can be pinched once to encourage side shoots, which helps produce more branches and more flowers. Growth is slow at the seedling stage, but it has the characteristic that small seedlings can bloom. As the seedlings grow, fertilizer and water management should be strengthened, and a dilute organic liquid fertilizer or 0.3% compound chemical fertilizer can be applied once every 10 days. This flower likes warmth and humidity and dislikes strong light. It is best placed in a spot that receives half a day of light or 70% light, with frequent water spraying around it, which keeps the plants full and the flowers blooming continuously. Large impatiens likes half-day light conditions, and sun-tolerant varieties have now been successfully bred, such as the Expo series, which can grow well under full sun, so they are also suitable for flowerbed planting.
Because Impatiens walleriana has the characteristic of liking semi-shade, it is very suitable for planting on household balconies or windowsills or under the shade of trees in courtyards. Old plants show degeneration in flowering, and the plants also become less attractive, so new plants should be replaced through cuttings, and attention should be paid to pruning.
1. Planting: Generally sown in spring from March to April. They can be sown in a seedbed or sown directly in a courtyard flowerbed. The seedlings grow fast, so thinning should be done in time, and after 1 transplanting they are planted out in the garden in early June. If sowing is delayed and the seedlings are potted, they can bloom around National Day.
2. Light and temperature: It likes light and also tolerates shade, and needs to receive at least 4 hours of scattered sunlight every day. In summer, shading is necessary to prevent excessively high temperatures and scorching sun exposure. The suitable growing temperature is 16-26°C, and the environmental temperature during the flowering period should be kept above 10°C. In winter, it must be moved into a greenhouse to prevent freezing.
3. Watering and fertilizing: After planting, water promptly. During the growing period, attention should be paid to watering, keeping the potting soil moist regularly, especially in summer when more watering is needed, but waterlogging and long-term excessive soil moisture must be avoided. If there is a lot of rain, attention should be paid to drainage and flood prevention, otherwise the roots and stems are prone to rot. After planting, fertilizing should be frequent, and especially care must be taken not to let the soil alternate between dry and wet. In summer, never water wilted plants under the scorching sun. Especially during the flowering period, they must not suffer drought, otherwise the flowers are prone to drop.
4. Flowering period control: If you want to delay the flowering period, you can sow in early July. You can also use the method of pinching, while removing early-opening flowers and flower buds, so that the plants keep growing larger, with a top dressing once every 15-20 days. After September, more flower buds will form, so that they bloom around National Day.
Pest and Disease Control
Sometimes brown spot disease and powdery mildew occur, which can be controlled by spraying 50% carbendazim.
1. Impatiens walleriana powdery mildew
Symptoms: This disease mainly occurs on leaves and tender shoots. It generally begins in June, and after July the leaf surface is covered with a white powdery layer. Subsequently, small yellow grains form in the white powdery layer, and the color gradually darkens, finally becoming dark brown. Transmission route: The pathogen overwinters in diseased plant residues and seeds. The following year, when environmental conditions are suitable, the pathogen spreads via wind and rain. August to September is the peak period of the disease.
[Control methods] Do not plant too densely, provide proper ventilation, strengthen fertilizer and water management, and enhance the disease resistance of the plants. Remove diseased leaves and diseased plants and destroy them centrally to reduce sources of infection. During the disease period, use 15% triadimefon wettable powder at 1000-1200 times dilution, or 70% thiophanate-methyl wettable powder at 1000 times dilution for control. Avoid spraying at high temperatures above 32°C to prevent phytotoxicity.
2. Impatiens walleriana brown spot disease
Impatiens walleriana brown spot disease is also called impatiens leaf spot disease. Symptoms: The disease mainly occurs on leaves. The leaf spots are initially small light yellowish-brown dots, then expand into round or oval shapes, after which the center becomes light brown and the edges brown, with indistinct concentric rings. On severely affected leaves, the spots merge into patches, causing the leaves to become withered and yellow, until the plant dies. Transmission route: The pathogen overwinters on impatiens diseased residues and soil plant debris. The following year, when environmental conditions are suitable, the pathogen spreads by wind and rain. It is prone to occur in hot and rainy seasons.
[Control methods] Impatiens walleriana likes fertile sandy loam and does not tolerate waterlogging. Therefore, sandy loam is suitable for planting to facilitate drainage; for potted Impatiens walleriana, pots should be tipped promptly after rain. In late autumn, diseased leaves and diseased plants should be destroyed centrally to reduce sources of infection for the coming year. In the early stage of the disease, use 25% carbendazim wettable powder at 300-600 times dilution, or 50% thiophanate-methyl at 100 times dilution, or 75% chlorothalonil at 1000 times dilution for control.
3. Impatiens walleriana damping-off disease
Symptoms: The pathogen mainly infects the root and stem area, causing the diseased area to turn black or constrict, and when moist, white mold-like growth appears on it. After the plant is infected, within a few days the leaves wilt and dry up, and then the whole plant dies. It mainly overwinters in the form of mycelium or sclerotia in the soil or in diseased residues. The mycelium in the soil lives saprophytically and does not go dormant. In the field, it is mainly transmitted by contact, that is, when the roots, stems and leaves of the plant touch diseased soil, they are infected by the mycelium in the soil. Under conditions with a water film, healthy leaves in contact with diseased parts become infected. In addition, seeds, farm tools and contaminated compost can all spread and expand the disease.
[Control methods] In the early stage of the disease, after removing the diseased plants, spray 75% chlorothalonil wettable powder at 600 times dilution, or 60% carbendazim · thiram wettable powder at 500 times dilution, or 20% tolclofos-methyl emulsifiable concentrate at 1200 times dilution.