Japanese Ivy (Hedera rhombea) belongs to the Araliaceae family and is a species native to temperate regions of Eastern Asia. This perennial evergreen plant is a versatile woody vine, shrub, or bush, known for its ability to climb up to 10 meters using aerial roots.
The plant features medium green, rhombic-shaped leaves with glossy, dark green surfaces and prominent petioles. Its stems are green and support its dense foliage, making it a popular choice for both decorative and functional gardening. During its flowering phase, Japanese Ivy produces small, greenish-yellow flowers, which are bisexual and gathered in large numbers in upright clusters known as umbrellas. Each flower measures about 4 to 5 mm in diameter, adding subtle charm to its overall appearance.
This resilient vine is well-suited for creating lush green walls, providing ground cover, or enhancing vertical spaces in gardens. Its unique foliage and understated flowers make it an attractive addition to any landscape.
| Common name | Japanese Ivy |
| Botanical name | Hedera rhombea |
| Family | Araliaceae |
| Species | rhombea |
| Origin | Temp. Eastern Asia |
| Life cycle | Perennial |
| Plant type | Vine |
| Hardiness zone | 8, 9 |
| Sunlight | Dappled Sunlight |
| Growth rate | Fast |
| Flower color | Gold, Yellow |
| Fruit color | Black |
| Garden style | Winter Garden |
| Uses | Container |
I. Appearance and Characteristics
Hedera rhombea, the Japanese ivy or songak, is a species of ivy in the Araliaceae family native to East Asia. Formerly named Hedera pedunculata, some subspecies could be subsequently classified as a distinct species. It is common on rocky slopes and growing up the trunks of trees, especially in laurel forest, a type of cloud forest.
Hedera rhombea is found in Japan, the Korean Peninsula, islands between Korea and Japan, the coast of mainland China and Taiwan. It is an evergreen climbing plant, growing to 10 m high where suitable surfaces (trees, cliffs, walls) are available, and also growing as ground cover where there are no vertical surfaces. It climbs by means of aerial rootlets which cling to the substrate. Stems are green, poisonous if eaten and have an irritating sap. It is cultivated in gardens and used in floral arrangements.
The leaves are medium green and have a rhombic diamond shape that give it its species name, rhombea. Leaves have a glossy, dark green petiole. The bisexual flowers are 4–5 mm in diameter and yellow-green, in erect umbels. The round fruits are black when ripe.
II. How to Grow and Care
Sunlight
Japanese ivy thrives in full sun conditions, where it can receive unfiltered light for most of the day. This exposure promotes vigorous growth and optimal health. However, japanese ivy is also adaptable to partial sun, tolerating less intense illumination without significant detriment. Under these suboptimal conditions, it may exhibit slower growth rates.
Adaptive traits such as potential leaf variegation could manifest in response to varying light levels, enhancing photosynthetic efficiency. When grown outdoors, Japanese ivy should be planted in a spot where it can benefit from adequate sunlight while withstanding light fluctuations inherent to its environment.
Temperature
Japanese ivy is native to Eurasia and North Africa. It prefers relatively cool temperatures and grows best between 10 to 27 ℃, preferably at around 18 ℃. While japanese ivy grows well in humid air, it can also withstand relatively low humidity. Moisten it by spraying water in dry seasons.
Watering
Thriving in its native woodland habitats, Japanese ivy has adapted to environments with consistent moisture. It exhibits a preference for evenly moist soil conditions and can tolerate high humidity levels, reflecting its origin from regions with ample rainfall. For optimal health, japanese ivy should be watered every week, ensuring the soil remains hydrated but not waterlogged. In indoor settings, japanese ivy benefits from regular misting to emulate its preferred humid conditions. As an evergreen plant, japanese ivy’s water needs are steady year-round, requiring attention to watering even during the cooler months when growth may slow.
Soil
Japanese ivy grows best in well-drained fertile soil, whether neutral and slightly acidic. The preferred pH ranges from 6.0-7.5. The plant tolerates poor soil and can survive in any loose, ventilated culture media. Mix garden soil or peat soil with leaf mold at 1:1 ratio to ensure long-term healthy growth and brightness of leaves. Replace the pot and half the soil once every year or two.
Fertilizing
For healthy growth, japanese ivy benefits from balanced nutrition fertilizers, while high nitrogen blends enhance leaf production. Fertilize monthly in the growing season, reducing to every 6-8 weeks in dormancy. Apply diluted to half-strength to protect delicate roots. Adjust feeding with plant age and season, boosting nitrogen in early spring for vigorous foliage. Always water soil before fertilizing to avoid root burn, ensuring a well-nurtured japanese ivy.
Planting Instructions
Propagate japanese ivy by cuttings in the spring and fall. The container should not be too large, or water may accumulate in the pot. Generally, you can cultivate 3-5 plants in one pot. When the plant is too large, replace it or prune the plant. Provide support for it to climb.
Pruning
Pinch young shoots from time to time to help branches grow and shape your plant. Cut off withered, yellow, or infected leaves of adult plants with clean scissors frequently. If the vines are too long, they can also be cut short once in spring every year. Japanese ivy is adapted to climbing scaffolds to get various shapes by pruning and pulling.
Propagation
As aerial roots grow well in moist air, Japanese ivy mainly reproduces through cuttings at any time except extreme weather like cold winter and hot summer. Use clean scissors to cut the lower part of the stem to 10 to 13 cm long. Remove the leaves 5 cm below the bottom and put it in water. Maintain a cool environment with relatively high air humidity. When the newly-generated root is 5 to 8 cm long, move into a pot.
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