How to Grow Impatiens walleriana? A Detailed Guide to Planting Methods

Impatiens walleriana is widely used and can be grown on a large scale in nutrition pots, containers and hanging baskets. At present, the main cultivated varieties of Impatiens walleriana on the market include ‘Accent’, ‘Victoria Rose’, ‘Jedi Storm’, ‘Nimbus’ and others.

Start of flower bud differentiation: 12 to 14 days after sowing; the 2nd to 4th leaves have grown.

Flowering habit: Impatiens walleriana is a day-neutral plant, and flowering is unrelated to day length.

Flowering mechanism: unrelated to light intensity; drought stress induces early flowering.

Plug germination stage: the following are the optimal conditions for seedling development; this stage begins with sowing and ends when the cotyledons unfold. The radicle is expected to emerge 2 to 5 days after sowing.

The seeds need to be covered with a thin layer of medium-grade vermiculite to retain moisture. The substrate pH is 6.2 to 6.5; a pH below 5.5 will cause damage to the growing tip and sodium toxicity; the EC value is 0.5 to 0.75. Seed germination requires light; if grown in a dark chamber, provide light at an intensity of 100 lux to 1000 lux to ensure germination and reduce stretching. Keep the moisture level at 5 until the radicle emerges; from day 3 to day 7 after sowing, lower the moisture level to 4; from day 8 to day 10, reduce it to 3; after day 11, reduce the moisture level to 2 until the cotyledons unfold (moisture levels: level 1 is 0% to 20%, level 2 is 20% to 40%, level 3 is 40% to 60%, level 4 is 60% to 80%, level 5 is 80% to 100%). Do not let the seedlings' leaves remain wet overnight, otherwise it will cause abortion of the plant apex. Keep air humidity at 100% until the radicle emerges; afterwards lower the humidity to 40% to 70%. Increase ventilation so that the substrate moisture evaporates and dries, ensuring root aeration. Keep the temperature between 22°C and 24°C; above 25°C, Impatiens seeds will suffer heat shock, thereby inhibiting germination; below 21°C, the germination speed and uniformity of Impatiens will be reduced; below 18°C, it will cause abortion of the plant apex and leaf deformity.

Full plug / flower bud differentiation stage: the following are the optimal conditions for the vegetative growth period of the seedlings; this stage begins when the cotyledons unfold. During this stage, the plant roots will extend to the edge of the plug cell, and the plant has completed its preparation for flower bud differentiation.

The growing substrate pH is 6.2 to 6.5; the EC value is 0.75; if it is greater than 1.25, it will cause abortion of the plant apex. The total EC of water and fertilizer should not exceed 1, to avoid leaf deformation. Provide 25,000 lux of light. In areas with low light levels, providing supplemental light of 3500 to 4500 lux for two consecutive weeks can promote strong and vigorous seedling roots and stems. However, in the early stage of plug culture, if light is provided for more than two weeks, it will cause seedling leaves to fade or turn yellow (photo-oxidation). Keep the temperature at 18°C to 20°C until the first true leaf forms, then lower the temperature to 16°C to 18°C to enhance color. Alternate the moisture level between level 4 and level 2, that is, first let the growing substrate moisture reach level 2, then raise it to level 4. Keep humidity at 40% to 50%. From day 2 to day 9 of this stage, apply calcium-containing fertilizer at a concentration of 25ppm to 50ppm (NPK ratio 14-0-14, same below), then apply 2 to 4 times 75ppm to 100ppm fertilizer containing potassium and calcium. Controlling the amount of fertilizer can keep the seedlings compact and promote flowering. Avoid applying phosphorus fertilizer, otherwise it will cause Impatiens walleriana seedlings to stretch; and adding phosphoric acid to the irrigation water will affect plug seedling quality.

The growth regulators that can be used for Impatiens walleriana include daminozide, paclobutrazol or uniconazole, but excessive use of growth regulators will cause immature leaves to develop inverted cup-shaped deformities or distortion. Plant growth can also be controlled by regulating water, light and fertilizer. Compared with other varieties, ‘Jedi Storm’ has different tolerance to plant growth regulators, so the use of plant growth regulators is recommended during the plug stage; in the later stage, plant growth can be controlled by regulating water and fertilizer. Under high temperature and high humidity conditions, the use of growth regulators has a color-enhancing effect on the plants.

Transplanting preparation period: 4 to 5 weeks after sowing in a 288 tray.

End of plug stage / flower bud differentiation stage: the following are the optimal conditions for the vegetative growth period; this stage begins with transplanting, and during this stage the plant roots will extend to the edge of the container and flower bud differentiation will take place.

The substrate pH is 6.2 to 6.5, and the EC value is 0.75 to 1. This stage requires shading. The night temperature is 16°C to 19°C, the day temperature is 21°C to 24°C, and the average daytime temperature is 19°C. Alternately regulate the moisture level between level 4 and level 2, that is, let the moisture level first reach level 2, then raise it to level 4. Keep humidity between 40% and 70%. Increase ventilation so that the substrate moisture evaporates and dries, ensuring root aeration. Apply 2 to 3 times 75ppm to 100ppm calcium-containing fertilizer (13-2-13 or 14-4-14). Controlling the amount of fertilizer can make the plants grow compactly and promote flowering; excessive fertilization will cause the plants to be too tall, with too many leaves, dark green leaf color, delayed flowering, or flowers below the leaves. The use of plant growth regulators is the same as above.

Post-harvest handling: treatment period is 1 to 2 weeks before harvesting or transport.

Use of growth regulators: foliar spray with daminozide at a concentration of 2500 to 3000.

Fertilizer: potassium nitrate fertilizer at a concentration of 150ppm.

Common diseases: Pythium root rot, gray mold, tomato spotted wilt virus, Alternaria leaf spot, damping-off, Impatiens necrotic spot virus, Pseudomonas bacterial diseases, etc. Cyprodinil is recommended to control gray mold and damping-off; metalaxyl-M is recommended to control Pythium root rot; azoxystrobin is recommended to control Alternaria leaf spot and damping-off.

Common pests: fungus gnats, thrips, aphids, red spider mites, etc. Recommended agents include thiamethoxam (for indoor use, eliminating pests while cutting off the transmission vector of viral diseases), spinosad (for indoor use), cyromazine, etc.

How to Grow Impatiens walleriana: How to Plant Impatiens walleriana

In the application of herbaceous flowers in Europe and America, Impatiens walleriana ranks first. It offers a wide range of bright colors and grows vigorously with simple management. It is suitable for tray and box containers, hanging baskets, flower walls, window boxes and balcony cultivation. A germination rate of more than 90% in plug trays has always allowed Impatiens to perform better than other series of varieties in all plug tray quality parameters, with the earliest flowering, the richest colors and free branching. The plants are covered with large masses of flowers, creating superb flowerbed and flower border landscapes, with a plant height of 20-25 cm. The colors of the leaves and flowers are very brilliant and richly varied, with more than 40 colors in total. Under the background conditions of shaded garden areas, the colors are harmonious, well-balanced and delicate, enriching and increasing the depth of the floral tones.

Cultivation management

The potting soil should be loose, fertile sandy loam. For example, using 1/2 peat soil or leaf mold mixed with 1/2 sandy loam plus some decomposed cake fertilizer powder or commercially available chicken manure is even better. Such soil is loose and fertile, more suitable for plant growth, and also beneficial to the growth of young plant roots. At the 2-leaf stage of the seedlings, they can first be pricked out once, and when about 4 cm tall, they can be planted in flower pots. When planting, it is best to choose a cool and humid environment for placement, to help the seedlings recover and survive, and also to help them bloom earlier. After the plants survive planting, they can be pinched once to promote side branches, which is beneficial for more branching and more flowering. Seedlings grow slowly, but they have the characteristic of being able to bloom as small plants. As the seedlings grow, fertilizer and water management should be strengthened; 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 to place it in a spot with half a day of light or 70% light, and spray water around it frequently, so that the plant can remain full and bloom continuously. Large Impatiens prefers half-day light conditions; 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 likes semi-shade, it is very suitable for growing on a home cool balcony or windowsill or under the shade of trees in a courtyard. Old plants show degeneration in flowering, and the plants also look less attractive, so new plants should be replaced through cuttings, and pruning should also be noted.

1. Planting: generally sown in spring from March to April. It can be sown in a seedbed, or directly sown in a courtyard flowerbed. Seedlings grow quickly, so thinning should be done in time; after 1 transplanting, they can be planted out in the garden in early June. If sowing is delayed, the seedlings can be potted and can bloom at National Day.

2. Light and temperature: it likes light and also tolerates shade, and needs at least 4 hours of scattered sunlight each day. In summer, shading should be provided to prevent excessively high temperatures and direct sun exposure. The suitable growth temperature is 16-26°C, and the environmental temperature during the flowering period should be kept above 10°C. In winter, it should be moved into a greenhouse to prevent freezing.

3. Watering and fertilizing: after planting, water promptly. During the growth period, pay attention to watering and keep the potting soil moist regularly, especially in summer when more watering is needed, but waterlogging and long-term overly wet soil must be avoided. If there is a lot of rain, attention should be paid to drainage and waterlogging prevention, otherwise the roots and stems are prone to rot. After planting, fertilize frequently, and especially avoid alternating dry and wet conditions. In summer, never water wilted plants under direct 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 plant continuously expands, with topdressing once every 15-20 days. After September, more flower buds will form, so that they bloom at National Day.

Pest and disease control

Brown spot disease and powdery mildew sometimes occur, and 50% carbendazim can be sprayed for control.

1. Impatiens walleriana powdery mildew

Symptoms: this disease mainly occurs on leaves and tender shoots. It generally begins to occur in June, and after July the leaf surface is covered with a white powdery layer. Subsequently, small yellow granules form in the white powdery layer, and the color gradually deepens, 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 by wind and rain. August to September is the peak period of the disease.

[Control methods] Do not plant too densely, provide appropriate 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 edge brown, with inconspicuous concentric rings. On severely affected leaves, the spots merge into patches, causing the leaves to become scorched 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, planting in sandy loam is preferable 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 following 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

Symptoms: the pathogen mainly infects the root and stem area, causing the affected part to turn black or constrict; when moist, white mold-like substances grow 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 soil or diseased residues in the form of mycelium or sclerotia. The mycelium in the soil lives saprophytically and does not dormancy. In the field, it is mainly transmitted by contact, that is, when the roots, stems and leaves of the plant contact 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 cause the disease to spread.

[Control methods] In the early stage of the disease, after removing 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.

Seed sowing and cutting propagation methods for Impatiens walleriana

The commonly used propagation methods for Impatiens walleriana include seed sowing and cutting propagation. Both propagation methods can be carried out throughout the year, but generally spring and autumn are better for propagation. Flower enthusiasts can choose a suitable propagation method according to their own conditions. Below are the seed sowing and cutting propagation methods for Impatiens walleriana, hoping to help flower enthusiasts better propagate Impatiens walleriana.

For seed sowing propagation of Impatiens walleriana, sowing can be done throughout the year. Prepare the seeds of Impatiens walleriana. Impatiens walleriana seeds are tiny, with 1700-1800 seeds per gram. When sowing, use a mixture of sterilized culture soil, leaf mold and fine sand. The suitable germination temperature is 22°C, and germination occurs 15-20 days after sowing. The suitable germination temperature for New Guinea Impatiens is 24-26°C, and germination occurs 7-14 days after sowing.

For cutting propagation of Impatiens walleriana, it can generally be carried out throughout the year, but spring and autumn are the best for cutting propagation. First select healthy terminal branches 10-12 cm long, and insert the branches into a sand bed. Under an environment of 20-25 degrees, generally after cutting, it takes about three weeks to take root and survive.