Ilex rotunda, commonly known as the round-leaved holly, is a small evergreen shrub belonging to the family Aquifoliaceae. Native to Japan and Korea, it can grow up to 2-3 meters in height. The plant has a dense, bushy form with glossy, dark green leaves that are round and have slightly serrated edges.
In late spring or early summer, Ilex rotunda produces small white flowers, which are followed by bright red berries that persist throughout the winter. These berries are an important food source for birds during the colder months.
This holly species prefers well-drained soil and partial shade but can also tolerate full sun if provided with adequate moisture. It is relatively low-maintenance, requiring neither regular pruning nor fertilization.
Kurogane holly is known to be a toxic plant, but the compounds it contains are still being studied by scientists. FUN FACT · FROM THE LIBRARY
Traditionally, Ilex rotunda has been used in medicine for its anti-inflammatory properties and as a treatment for various ailments such as fever, coughs, colds, and headaches.
Overall, Ilex rotunda is an attractive evergreen shrub with ornamental value due to its glossy foliage and bright red berries. It is an excellent choice for garden borders or hedging purposes.
The Ilex rotunda, commonly known as Kurogane holly, Small-fruited holly, or Round leaf holly, is called 'Kurogane-mochi' in Japanese, which translates to 'black iron holly.' The English name 'Kurogane holly' partly originates from this Japanese term, and it is now the common reference for this type of holly.
Kurogane holly is resistant to disease and is generally unlikely to develop illnesses. In terms of care, this plant is fairly low-maintenance. When grown outdoors it needs only light watering, and larger plants typically do not require pruning. Smaller plants, however, should be pruned after they have finished blooming. Kurogane holly is suitable for anyone with outdoor space, such as a garden or deck, and does not require much experience in plant care.
How to keep Ilex Rotunda.
Light
Kurogane holly requires abundant sunlight to develop vigorously, though it can tolerate locations with occasional shade. Its ancestral habitat consists of areas receiving strong sun exposure. Too much or too little light can harm the plant’s health and may cause weak, discolored foliage.
Water
Kurogane holly thrives in well-drained, moderately moist environments and can tolerate drought conditions. It typically needs watering every two weeks and is best grown outdoors. This plant flourishes in climates where the rainfall matches its growth cycles.
Temperature
Kurogane holly grows best in its native growing environment at temperatures between 50 and 95 °F (10 to 35 °C). Seasonal temperature adjustments may be needed to replicate its natural habitat.
Fertilizer
The timing of fertilizing Kurogane holly is important. Apply fertilizer in early spring and continue monthly until early summer. Fertilizer encourages attractive blooms and supplies energy during both dormant and active growth phases.
Pruning
Kurogane holly, known for its glossy evergreen leaves and vibrant red berries, benefits greatly from winter pruning while the plant is dormant. Effective pruning techniques include thinning to improve airflow, removing damaged branches, and selectively cutting to encourage new growth. This care not only enhances the appearance of the kurogane holly but also strengthens its structure, making it a striking addition to any landscape.
Pot & Repot
To help your kurogane holly thrive, repot it every 2-3 years in early spring. Use a container that is one size larger than the current one. Ensure the new pot has good drainage to support healthy growth. After repotting, carefully monitor the plant's watering and light conditions for a few weeks to minimize stress and promote recovery.
Botanical profile.
- Plant Type
- Tree
- Life Cycle
- Perennial
- Genus
- Ilex
- Family
- Aquifoliaceae
- Hardiness Zone
- 6-9
- Mature Height
- 15.24 m
- Mature Spread
- 10.67 m to 13.72 m
- Leaf Color
- Green, Blue
- Leaf Type
- Evergreen
- Flower Color
- White
- Flower Size
- 0.51 cm
- Bloom Time
- Mid spring, Late spring
- Planting Time
- Spring, Autumn
- Harvest Time
- Mid summer, Late summer
- Native Area
- Vietnam, Japan, Laos, South Korea, China
Other names.
Reader questions.
How should I water my Kurogane holly plant?
Your Kurogane holly doesn't have specific requirements for watering methods. You can use any common watering tool like cans, hoses, or even cups. Just make sure to water the soil directly and evenly, giving all parts of the root system the water they need. Using filtered water is better than tap water because tap water may have harmful particles. It's also best to use water that is at or slightly above room temperature, as extremely hot or cold water can be shocking for the Kurogane holly. However, the plant generally responds well to any type of water you use.
Why should I put fertilizer on my Kurogane holly?
No matter which type of Kurogane holly you own, regular fertilization is crucial for its overall health. Providing the proper nutrients will result in stronger growth and make your Kurogane holly more resilient to harsh conditions, as well as more capable of combating diseases and pests. Preserving the attractive foliage of your Kurogane holly is important, so it is necessary to establish and stick to a specific fertilization schedule for your plant. By doing this, you can encourage the development of vibrant, rich-colored leaves that enhance the overall appearance of your Kurogane holly.
How many hours a day should Kurogane holly be exposed to sunlight in order to grow healthily?
To ensure healthy growth, ensure that Kurogane holly gets a minimum of 3-6 hours of sunlight each day. Most plants that can tolerate part sun can also thrive in full sun, but since they require less light for photosynthesis, they are more adaptable than plants that require either full sun or part shade.
What is the best temperature for Kurogane holly?
The ideal temperature for Kurogane holly to thrive is between 65 and 80°F (18-27°C). During the main growing phase, it can tolerate temperatures up to 95°F (35°C) at the highest and as low as 15°F (-10°C) at the lowest. This species is able to survive freezing winters since it can handle low temperatures. The recommended temperature ranges are: Perfect: 65-80°F (18-27°C), Highest: 85-95°F (30-35°C), Lowest: -5 to 15°F (-20 to -10°C) or below.
What do I do if I give too much or too little water to my Kurogane holly?
Outdoor plants, especially newly planted ones or seedlings, can suffer from lack of watering. To ensure proper growth, it is important to consistently water them for a few months, especially when they are small or newly planted. Once the roots are established, Kurogane holly plants can usually rely on rainwater. When Kurogane holly is planted in pots, overwatering is more likely. If you accidentally overwater your plant, take immediate action to address the issue. Firstly, stop watering the plant to minimize the impact of overwatering. Then, carefully remove the plant from its pot and examine the roots. If there are no signs of root rot, you can return the plant to its container. However, if you notice signs of root rot, trim the affected roots and consider using a fungicide to prevent further damage. Finally, repot the Kurogane holly in well-draining soil. In the case of underwatering, simply water the Kurogane holly more frequently. This is an easy fix, as the plant's leaves tend to droop, dry out, and fall off when underwatered. Once the plant receives sufficient watering, the leaves will quickly regain their fullness. Remember to adjust your watering frequency promptly when you notice underwatering occurring.
When should I fertilize my Kurogane holly?
To properly fertilize your Kurogane holly, start by applying fertilizer in late winter or early spring. This will give the plant the necessary nutrients for healthy growth once the weather warms up. Additionally, in warm climate regions, it is beneficial to provide another round of fertilizer in early fall. This not only adds nutrients for the following growing season but also helps the holly become more resilient, preventing foliage damage during winter. Early fertilization is particularly important to give new branches enough time to grow and withstand the cold.
What kind of sunlight does Kurogane holly require?
Kurogane holly thrives in full or part sun. It is ideal for them to receive direct morning light, but during the summer, they should be shielded from the intense afternoon sun. In temperate environments, excessive hot afternoon sun can scorch the leaves, harming the plant's overall look and well-being.
Do I need to change the temperature for Kurogane holly as it grows?
According to research, Kurogane holly may show signs of stunted growth when exposed to high temperatures for a long time, particularly when axillary buds are developing and main shoots are growing. To promote healthy growth after germination or transplanting, it is recommended to maintain consistent and cooler temperatures at around 65℉ (18℃).
How often do I need to water my Kurogane holly?
Plants usually grow fine with natural rainfall, but if your area doesn't get much rain, you'll need to water your plants every 2 weeks in spring and fall, and more often in the summer. In winter, when plants grow slower and need less water, you can water them less frequently or not at all. Young or newly planted Kurogane holly plants need more water to establish themselves and become more drought tolerant. For potted plants, there are two main ways to determine how often to water your Kurogane holly. The first way is to follow a set watering schedule of once a week or once every other week. However, this may not always be accurate for your specific growing conditions. You can also determine watering frequency based on the moisture of the soil. Wait until the top two to four inches of soil have completely dried out before giving more water. This method is especially important during the summer when the plant's water needs are highest.
When is it best not to add fertilizer to my Kurogane holly?
There are specific times of the year when you should avoid fertilizing your Kurogane holly. The first instance is in the early and mid-winter when the plant is dormant and does not need any nourishment. It is also not recommended to fertilize this plant in the late spring and throughout the summer because the weather is hotter and drier. These conditions can negatively affect the response of your Kurogane holly to fertilization. To prevent any issues, it is best to follow a fertilization schedule and only feed the plant in early spring and early fall.
Can the sun harm Kurogane holly? How can I keep Kurogane holly safe from the sun and heat?
Indoor Kurogane holly plants are easily harmed by direct sunlight when they are relocated outside. To avoid sunburn from excessive exposure, it is best to gradually move the pots from a shaded area to a brighter spot. However, even plants accustomed to the summer sun can be harmed by extreme heat. During a heatwave, it is crucial to keep the soil consistently moist to help the plants withstand the intense heat. In case of extreme weather conditions, such as high temperatures, it is advisable to move potted plants to shaded locations or use a shade cloth for protection.
How can I make sure Kurogane holly stays warm during the cold seasons?
Kurogane holly is a hardy plant that can handle frost when planted directly in the ground, as long as the temperature doesn't drop below 15℉(-10℃) in your area during winter. However, if you're planting it in pots or containers, it's important to protect the roots from the cold. You can do this by wrapping the container in a blanket or bringing it indoors to keep it fully shielded from the elements.
