The Japanese Ardisia is the kind of shrub that stays compact throughout its life. With lush green leaves, pinkish flowers, and cherry-like fruits, its ornamental values make it hard to miss. And being an evergreen plant is just the icing on the cake.
The shrub grows well in sheltered places since its root system is not strong enough to withstand strong winds. But other than that, the Japanese Ardisia is a self-sufficient plant that needs little care and is not fussy about the growing conditions.
Read more to find out how to grow and care for this evergreen shrub and how to protect it from the various growing problems you might encounter.
All About Japanese Ardisia
Whether you call it Japanese Ardisia or marlberry, this low-growing shrub is a delightful groundcover. It used to have some more imaginative names such as Bladhia, Bladhia japonica, and Ardisia odontophyllum. But with a short stature that doesn’t exceed 12 inches, the shrub is happy to cover any drab corner in your garden and transform the landscape dramatically.
Not many groundcovers produce flowers and fruits. For the most part, they’re happy to add a splash of green on the ground. But the marlberry ups the ante with its pinkish flowers and red berries. The leaves are small and oval-shaped. The dark green leaves usually grow at the top of the short branches, and the dense foliage literally glitters in the sun.
Native to Japan, Korea, and Taiwan, it grows best in zones 8 and 9. Its original habitat is usually partially shaded as it grows in the shadow of bamboo forests. The shrub, however, self-seeds, so you’ll need to either deadhead the flowers or pluck the berries before they ripen to prevent the spread of the shrub.
Besides its lush foliage, the shrub offers small star-shaped flowers to complement the green groundcover. The flowers open in July and stay in bloom throughout August. After they pollinate, small cherry-like fruits appear. They turn bright red between October and November and might stay on the shrub throughout winter. The fruits are packed with seeds that await the next spring to spread on the ground and start new plants.
Japanese Ardisia Uses
Growing in Japan, Korea, and the eastern regions of China, the Japanese Ardisia quickly became part of many rituals, cultural events, and, of course, medicine. The evergreen shrub serves many decorative purposes, and the red berries have medicinal properties. Here are some of the historical uses of marlberry that persist even today.
- The marlberry is a fixture of Japanese New Year celebrations.
- Some cultivars with variegated leaves are grown for their ornamental values.
- Grow the marlberry as a groundcover in partial shade or dim-lit parts of the garden or lawn where turfgrass doesn’t grow. However, it has a low tolerance for foot traffic.
- In Chinese traditional medicine, the shrub is considered one of the 50 fundamental herbs where it goes in just about any concoction and prescription from scabs and acne to gout and digestive problems and consumption.
- Don’t take the Japanese Ardisia as a self-prescribed medicine. If consumed in large doses, it can cause kidney damage.
Japanese Ardisia Varieties
Due to its versatility and ornamental properties, Japanese Ardisia has become a popular garden fixture. New cultivars were developed to meet the market needs for variety and different colors. These cultivars mainly offer variegated foliage and long-lasting blooms. Here are some of those cultivars.
- Ito-Fukurin: A cultivar grown specifically for Japanese and Korean gardens. The leaves are gray-green with white thin lines around the edges. The flowers are mostly white.
- Nishiki: Another cultivar with variegated foliage. However, the leaves here are a combination of cream and pink. When the leaves mature, they turn creamy yellow.
- Chirimen: A hardy cultivar with excellent tolerance for cold weather. The leaves are green, but you can grow them in zones 6 to 9 without any problems.
- White Cap: This cultivar is similar to Ito-Fukurin. It has gray-green foliage with thick white lines outlining each leaf. It has a low tolerance for bright light and cold weather, so you can grow it if you live in zones 8 and 9.
How to Grow Japanese Ardisia
Although Japanese Ardisia starts easily and quickly from seeds, this is not the recommended way to grow it. Since the shrub is not native to the US, there’s no guarantee that the seeds you’ll order online will grow in your zone. So for the best results and for convenience, you should get saplings from the local nursery. Here’s how to start marlberry in your garden in easy steps.
- Choose a spot in your garden that doesn’t get a lot of foot traffic.
- Turn up the top 10 inches of the soil and mix in organic materials at a ratio of 1:1.
- Dig a hole twice the width of the root ball of the shrub and line it with aged manure or organic compost.
- Ease the shrub out of the container it came in and examine the roots. Trim off any damaged or entangled roots and ruffle them with your hand.
- Place the shrub in the hole so that the edge of the hole aligns with the soil line on the stem.
- Backfill the hole with the mixture of soil and homemade fertilizer and pack it firmly to push out air pockets, and make sure the shrub is standing upright.
- Water the shrub immediately to get the soil moist and help it settle.
- Cover the ground around the parameters of the shrub with a thick layer of mulch to prevent weeds from competing with the young shrub. Keep the mulch on the ground until the marlberry establishes in the soil.
- If the shrub you bought is large, you might need to build a well around the drop line of the shrub. This will keep the soil moist during the hot summer months.
Japanese Ardisia Care
The three main tasks that you need to pay attention to when caring for the Japanese Ardisia are watering, light, and pruning. You still need to feed it and ward off some pests and treat a few diseases. But if you get those three right, your marlberry shrubs will not give you much trouble. And, of course, you shouldn’t step on them or treat the shrubs like turfgrass. They’re sensitive to foot traffic.
As an evergreen perennial, your soil choice will be one of the first decisions to make right after selecting the right time to start the groundcover. That’s because the Japanese Ardisia grows in the garden, which limits your ability to amend the soil or even change it once the plant is in the ground. So test your soil first and make sure it’s more sandy and loamy than pure loamy. Heavy soil doesn’t promote the growth of the root system of this delicate perennial. Amend the heavy or loamy soil with perlite or coarse sand to improve the texture and make it loose enough. As for the pH, it should be slightly acidic between 6.0 to 6.8. Adding lime will help make the soil more acidic.
One thing is clear about the marlberry. It doesn’t like direct exposure to the sun and is happy with either partial or full shade. As a groundcover, the plant in its natural habitat in East Asia barely gets the full sun. It grows in the shadow of larger and taller plants and trees with dense canopies. So what little sunlight filters through is not harsh enough to damage the foliage of the perennial or its flowers.
That said, you should err on the side of partial shade. Full shade can bring in its own set of problems, including waterlogged soil, fungal infestations, and pests hiding in the dense foliage of the plant. As long as you protect the marlberry from the afternoon sun, it should be fine.
Like most other perennials, the Japanese Ardisia requires one inch of water every week. If you live in a dry zone, you’ll need to provide the full one inch of water yourself. The plant’s roots are too close to the surface to get moisture from the deep recesses underground. But if you get decent rainfall, then you’ll need to supplement the rest of the quota with irrigation. Your goal is always to keep the soil moist without getting it wet or allowing it to dry out. As an evergreen plant, your watering will continue all year round. However, when the temperature cools down in the fall and winter, you can cut back on watering and provide a half-inch a week. The soil is your guide. If the top 2 inches are still moist, you don’t need to water the plant just yet.
The feeding habits of the Japanese Ardisia vary depending on its age. The young plant where the roots are still developing requires more phosphorus than nitrogen in its plant food. Sprinkle a custom 5-10-10 fertilizer in the hole before you plant the young shrub. Apply the same fertilizer once every 3 weeks during the first growing season.
Once the shrub establishes, you can switch to a balanced 10-10-10 fertilizer with enough nitrogen to promote robust foliage growth. The marlberry will still need phosphorus for the beautiful flowers. Apply the balanced fertilizer once every 3 weeks during the spring and summer. Side dress with compost and age manure once every 4 weeks during the growing season. Hold back all types of plant food during the fall and winter since new growths in the winter cannot survive in the cold winter months.
When it comes to pruning, marlberry demands different types of pruning depending on its stage in life and the season. The most common pruning techniques you need to provide the shrub are shearing, thinning, pinching, and rejuvenating.
- Shearing: As the name indicates, shearing is a process in which you cut off the top of the shrub to make it level. Its goal is to maintain the plant’s shape and keep it close to the ground. You can use pruning shears or electric shears.
- Thinning: You would thin out the branches of the shrub to remove disentangled or damaged branches. It also opens paths to the interior of the shrub to improve air circulation and prevent fungal buildup. This is an ongoing process that you perform any time of the year as needed.
- Pinching: You will usually pinch the tips of the young marlberry plant to promote branching and encourage the plant to grow lateral branches and spread horizontally. You only need to do this during the first growing season of the shrub’s life.
- Rejuvenating: When the shrub outgrows the space you planned for it or becomes burdened with old and twisted branches, it’s time to cut back the Japanese Ardisia to its original size. It’s recommended that you don’t cut back more than one-third of the plant to avoid damaging its structure. You can do this in the fall or early winter.
Pests and Diseases
For the most part, the Japanese Ardisia is immune to most diseases that other shrubs and evergreen plants in the garden get. As for pests, the only bug that causes the most damage to the shrub is the mealybug. You have encountered it before feeding on many plants in your garden. It looks like a tuft of cotton perched on the leaves and branches of the marlberry. Even if you see only one mealybug on the bush, you should spring to action since more bugs are probably hiding in the dense foliage.
The best way to fight off the mealybug is to attract ladybugs to the garden. Ladybugs feed on the mealybugs without causing damage to the marlberry. You can also spray the shrub with neem oil once every three weeks during the spring and summer.