Origin
Hemerocallis japonica (Thunb.) Thunb. 1784, non Thunb. 1794, commonly known as daylily, is a perennial herbaceous plant native to Japan, China, and Korea. It is widely cultivated in gardens and landscapes around the world.
Common Names
Besides daylily and its scientific name Hemerocallis japonica, this plant is also known as Orange Day Lily, Asphodel Lily, Tawny Daylily, Kwanzo Lily, or Himeyuri.
Uses
Hemerocallis japonica is mainly used as an ornamental plant due to its vibrant, showy flowers that bloom abundantly from late spring to early summer. Its leaves are also attractive, with a deep green color and slender, elongated shape. Some cultivars have variegated leaves of different hues.
Daylilies can be grown in borders, rock gardens, containers, or as a groundcover. They are easy to cultivate, adapt well to various soil types and climates, and tolerate drought and heat. The flowers are edible and can be used in salads, soups, or stir-fries, adding a hint of sweetness and a touch of color. However, caution should be taken because some daylily species are toxic to humans and pets.
General Appearance
Hemerocallis japonica has a clumping growth habit, with multiple stems emerging from a crown that is anchored by fleshy roots. The stems are up to 1 meter tall and bear a terminal inflorescence that consists of several large, trumpet-shaped flowers, each up to 10 cm across. The flowers are typically orange-yellow with dark red or mahogany markings in the throat, but there are also cultivars with red, pink, peach, or cream flowers. The flowers last for only one day, hence the name "daylily". The foliage is deciduous, with leaves up to 90 cm long and 2 cm wide, arranged in a fan-like pattern. The fruit is a capsule that contains numerous flat, black seeds.
Light Requirements
Hemerocallis japonica typically requires a good amount of sunlight to grow well. Ideally, it should be planted in an area that receives at least six hours of direct sunlight each day. However, during hot and dry weather, some afternoon shade may be helpful to prevent the plant from drying out.
Temperature Requirements
The plant prefers moderate temperatures. It can tolerate cold temperatures down to USDA Zone 3. However, it grows best in areas with mild winter temperatures in USDA Zones 5-9. In areas with hotter summer temperatures, providing afternoon shade or planting the plant in a location with good air circulation is crucial to prevent heat stress.
Soil Requirements
Hemerocallis japonica prefers well-draining fertile soil that is slightly acidic in nature with a pH of 6 to 6.8. The soil should be slightly moist; however, overwatering should be avoided, as it can lead to root rot. It can tolerate a range of soil textures, including sand, loam, and clay, but prefers loamy soil. An application of 2 to 4 inches of organic matter, such as compost or well-rotted manure, can promote healthy plant growth and development.
Cultivation Methods for Hemerocallis japonica
Hemerocallis japonica can be grown from seeds, division of mature plants or rhizomes. The plant prefers well-drained loamy soil that is rich in organic matter. It grows best in full sun or partial shade, but in hot climates, it may require some afternoon shade to avoid leaf scorching.
Watering Needs for Hemerocallis japonica
The plant requires moderate watering, and soil should be moist but not waterlogged. It is best to water Hemerocallis japonica in the morning or evening to avoid water evaporation and prevent wet foliage, which can cause diseases. During the summer, watering should be increased to prevent soil from drying out completely.
Fertilization for Hemerocallis japonica
Fertilization of Hemerocallis japonica should be done in the early spring and again in the late summer or fall. A balanced fertilizer with a higher ratio of phosphorus and potassium than nitrogen is recommended to encourage bloom and root growth. The fertilizer should be spread evenly around the plant and watered after application.
Pruning of Hemerocallis japonica
Hemerocallis japonica requires minimal pruning. The plant naturally dies back in the winter and regrows in the spring. Dead foliage and spent flower stalks can be cut back to the base of the plant in the fall or early spring. Stem tips may be pinched off in the summer to encourage branching and more blooms.
Propagation of Hemerocallis japonica (Thunb.) Thunb. 1784, non Thunb. 1794
Hemerocallis japonica is commonly propagated by division. This method is best done in the spring, just as the new leaves start to emerge. Carefully dig up the clump and separate the individual plants, making sure each division has roots and leaves attached. Replant the divided plants at the same depth they were previously growing, and water them well.
Another propagation method for Hemerocallis japonica is by seed. Collect the ripe seed pods from the plant after they have turned brown and split open. Let the seeds dry out for a few days before sowing them in pots or directly in the garden. Cover the seeds lightly with soil, and keep them moist until they germinate.
Hemerocallis japonica can also be propagated by tissue culture. This method involves taking a small piece of tissue from the plant and, under sterile conditions, allowing it to grow in a nutrient-rich media. Once the tissue has grown into a small plantlet, it can be transferred into soil and grown into a mature plant.
Finally, Hemerocallis japonica can also be propagated by root cuttings. This method involves taking a piece of root, typically about 5-10 cm in length, and planting it horizontally in soil. Keep the soil moist, and in a few weeks, new shoots should emerge from the root cutting.
Disease Management
Hemerocallis japonica is susceptible to various fungal and bacterial diseases that can cause significant damage to the plants. Below are some common diseases that affect this plant and ways to manage them:
Crown Rot
Crown rot is a fungal disease that affects the plant's crown and can lead to the death of the plant. The infected plant typically shows wilted and yellowed leaves. To manage this disease, remove the infected plants and avoid planting in poorly drained soil. Additionally, avoid overwatering and over-fertilizing the plants.
Leaf Spot
Leaf spot is a fungal disease that manifests as small, circular spots on the leaves. The spots are usually brown or black and may have a yellow halo around them. The disease can cause defoliation, which can affect the overall health of the plant. To manage this disease, remove the infected leaves and improve air circulation around the plant. Avoid overhead watering, and apply fungicides to protect new growth.
Powdery Mildew
Powdery mildew is a fungal disease that forms a white or gray powdery substance on the leaves, stems, and flowers. The disease can weaken the plant, reducing its overall health and yield. To manage this disease, prune the affected areas, and avoid overcrowding of plants. Additionally, avoid over-fertilizing, and apply fungicides to protect new growth.
Pest Management
Hemerocallis japonica is also susceptible to various pests that can cause significant damage if left unmanaged. Below are some common pests that may affect this plant and ways to manage them:
Aphids
Aphids are small insects that suck the sap from the plant, leading to wilting and stunted growth. The pests also excrete a sticky substance that attracts ants and causes fungal growth. To manage aphids, spray the plants with a strong jet of water, introduce natural predators, and apply insecticidal soap or neem oil.
Thrips
Thrips are tiny insects that feed on the plant's leaves, flowers, and buds. They can cause significant damage, leading to distorted leaves and reduced flower production. To manage thrips, prune off infected areas, remove weeds around the plant, and apply insecticidal soap or neem oil.
Spider Mites
Spider mites are tiny insects that feed on the plant's sap, causing yellowing and stippling of leaves. The pests also create fine webs that cover the plant, reducing its overall aesthetic appeal. To manage spider mites, spray the plants with a strong jet of water, improve air circulation around the plant, and apply insecticidal soap or neem oil.
