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Carmona retusa is a plant that originates from Asia. It is a member of the Rutaceae family and is also known as the Japanese box. The plant is an evergreen shrub that can grow to be up to three meters tall. Carmona retusa has glossy green leaves and white or pink flowers that bloom in the summer. The plant is popular in bonsai due to its small leaves and dense branching. Carmona retusas are slow-growing but can live for many years with proper care.

Also known as

• Rottlera tinctoria
  
• Pullea tinctoria
  
• Rottlera lutea
  
• Rottlera indica
  
• Rottlera foeniculacea

Basic info

• Carmona retusa is a small shrub or tree native to southern China and Taiwan.
  
• It is commonly known as the false or Chinese boxthorn.
  
• The plant has small, glossy green leaves and produces white or pale pink flowers.
  
• The fruit is a small, dark red berry.
  
• Carmona retusa is often used as an ornamental plant in gardens.
  
• The plant is poisonous to humans and animals if ingested.
  
• Carmona retusa can cause skin irritation and allergic reactions in some people.
  
• The plant can be invasive and difficult to control once established.
  
• Carmona retusa is tolerant of a wide range of environmental conditions.
  
• It is relatively easy to propagate from cuttings.

Growing Steps

1. For carmona retusa, first step is to find a suitable location. The plant prefers full sun and well-drained soil.
   
2. Next, dig a hole that is twice the width and depth of the plant’s root ball.
   
3. Place the plant in the hole and fill it with soil, gently pressing down as you go.
   
4. Water the plant deeply.
   
5. Mulch around the plant to help retain moisture.
   
6. Fertilize the plant every few weeks during the growing season.
   
7. Prune the plant as needed to shape it and encourage new growth.
   
8. Watch for pests and diseases, and treat accordingly.
   
9. Harvest the plant’s berries when they are ripe.
   
10. Enjoy your carmona retusa plant!

Related plant:
Bonsai Carmona

Soil Condition

About soil condition, Carmona retusa prefer well-drained soils that are high in organic matter. They are not tolerant of drought or of wet, poorly drained soils. They are best grown in full sun but can tolerate some shade, especially in hot summer climates.

Light condition

Like the other evergreen shrubs, carmona retusa need full sun to partial shade to maintain its foliage color and to prevent leaf scorch, especially during the heat of summer. It is a tough, drought-tolerant plant once established. It can handle full sun in coastal areas but may need some afternoon shade inland.

Good Temperature

The temperature condition that is optimal for growth of Carmona retusa is between 18-24°C. Carmona retusa is a tropical plant and cannot tolerate freezing temperatures. If the temperature drops below 18°C, the leaves of the plant will start to turn brown and fall off. If the temperature gets too high, above 24°C, the leaves will start to wilt and the plant will stop growing. The ideal temperature for growth of Carmona retusa is between 18-24°C.

Humidity Aspect

Ideal humidity condition for this plant is between 40 to 50%. If the humidity is too high or too low, the plant will suffer and may eventually die. The leaves will start to turn brown and drop off if the humidity is too low. If the humidity is too high, the leaves will start to yellow and drop off.

Fertilizing

Regarding fertilizer, this kind of plant requires little to none. Carmona retusa are known to be able to grow in nutrient-deficient soils. When it comes to the roots, they are quite shallow. Because of this, the plant does not do well in areas that experience heavy rainfall.

About light

Pruning is an important aspect of caring for a Carmona retusa plant. By pruning, you can encourage the plant to produce new growth and maintain a tidy appearance. When pruning, be sure to remove any dead or damaged leaves and stems. You can also trim back any straggly or overgrown branches.

About Propagating

Propagation is typically done through rooting stem cuttings taken from the parent plant. The stem cuttings should be taken from new growth and should be 4-6 inches long. The cuttings should be placed in a well-drained potting mix and kept moist. After a few weeks, the cuttings should develop roots and can be transplanted into individual pots.

Growth Speed

Usually, the plant growth rate studies have found that this species of plant has a very high growth rate. However, there is little information on the long-term effects of this species on the environment.

Common Problems

Common problems for this kind of plant are over watering, too much sun, and not enough drainage. Over watering can cause the leaves to turn yellow and the stem to rot. Too much sun will cause the leaves to turn brown and dry out. Not enough drainage will cause the roots to rot.

Tips on Growing

• Make sure to give your carmona retusa plant plenty of sunlight. It needs at least six hours of sunlight each day.
  
• Water your plant regularly. Keep the soil moist, but not saturated.
  
• Fertilize your plant every four to six weeks with a high-quality fertilizer.
  
• Prune your plant regularly to encourage new growth.
  
• Protect your plant from extreme temperatures. It should be kept in a cool, dry place.
  
• Keep your plant free from pests and diseases. Inspect it regularly and treat problems promptly.
  
• Repot your plant every two to three years. Use a pot that is slightly larger than the previous one.
  
• Propagate your plant by taking stem cuttings.
  
• Place your plant in a location where it will receive good air circulation.
  
• Enjoy your beautiful carmona retusa plant!

Similar Plants

• Japanese Photinia (Photinia fraseri subsp. forrestii)
  
• Japanese Photo (Photinia macrocarpa)
  
• Japanese Photogal (Photogallus contortus)
  
• Japanese Photoelectric (Photogale ampelotis)
  
• Japanese Photomicrograph (Photomicrographus brevispinosus)
  
• Japanese Photometer (Photometra aestivalis)
  
• Japanese Photon (Photon fitchii)
  
• Japanese Photon (Photon ponticus)
  
• Japanese Photonic (Photosophyte ponticum)
  
• Japanese Photovoltaic (Photosophyta voltae)

Source:
(PDF) Carmona Retusa (Tsaang gubat) Roots and Stem ... - academia.edu
The effects of Carmona retusa leaf Extract (wild tea) on the ...
Structure of an antimutagen from Carmona retusa leaves.