Mandarin Orange (Citrus reticulata)

The mandarin orange (Citrus reticulata) is a citrus fruit tree. It is famed for its Mandarin oranges, a commonly consumed fruit which can be eaten plain or used in salads. During the Chinese New Year, the fruit is considered a symbol of good fortune.

I. Appearance and Characteristics

The mandarin tree, Citrus reticulata, takes its name from the color of its fruit, similar to that of the silk robes worn by high-ranking officials known as mandarins. Cultivated in China, Vietnam and the Philippines for centuries, it wasn’t until the early 19th century that the Portuguese introduced this variety of the Rutaceae family to Europe. Although the mandarin tree is gradually being replaced by clementine in orchards, it remains a highly appreciated ornamental shrub.

The mandarin tree, Citrus reticula, is a compact shrub as wide as it is tall. When fully mature, it can grow to between three and five meters in all directions. The crown is ball-shaped. Highly branched, it is made up of slightly thorny branches.

The branches are covered with evergreen foliage. The smooth, lanceolate, alternate leaves are four to eight centimetres long. When crumpled, the leaf blades give off a tangy scent.

In mild climates, particularly around the Mediterranean, Citrus reticulata blooms in winter. Elsewhere, you’ll have to wait until spring to see the two- to four-centimetre-long white flowers. Their fragrance attracts pollinators.

The fruit of the mandarin tree resembles that of the orange tree, only smaller. Mandarins are orange spheres, flattened at the tip, five to eight centimetres in diameter. Each one is divided into quarters and contains numerous seeds. This characteristic has earned them the dislike of gourmands, who prefer clementines.

II. How to Grow and Care

Sunlight

Mandarin orange thrives in conditions of full sun, basking in at least 6 to 8 hours of direct light daily to optimize growth and fruit production. It can tolerate partial sun, yet with reduced sunlight, mandarin orange may exhibit less vigorous growth and diminished fruit yield. The plant showcases adaptive traits such as glossy leaves that reflect excess light, safeguarding against intense sunlight. Mandarin orange is best planted outdoors in areas that receive ample sunlight throughout the day, positioned away from shadows cast by larger plants or structures to ensure sustained exposure to bright conditions.

Temperature

Mandarin orange prefers a warm, moist environment. Optimal temperatures for its growth are 15 to 30 ℃, while it can tolerate a high temperature of 35 ℃ for a short time. Temperatures higher than 38 ℃ can suppress the growth of mandarin orange. It can survive 0 ℃ briefly, but to avoid damage, keep it above 5 ℃ in winter.

Mandarin orange has a high need for water. Especially in spring and fall, when it grows vigorously, regular and deep watering is needed to keep the soil moist. Mandarin orange goes dormant in winter, so not much watering is needed then. Keep the soil semi-dry and well-drained. Be aware that overwatering may cause root rot, which can lead to death.

Watering

Mandarin orange is a plant that has adapted to moderate water conditions, indicative of its origins in the subtropical regions. It exhibits a relative balance in terms of water needs, neither excessively thirsty nor particularly drought-tolerant. This species typically requires watering once every 1-2 weeks to maintain optimal health and growth. As an evergreen plant commonly grown outdoors, mandarin orange thrives best when it experiences rainfall similar to its native habitat during its growing season.

Soil

Mandarin orange thrives in well-draining soil. A suitable mix can be 1 part peat, 1 part pine bark, and 1 part perlite or coarse sand to enhance aeration and drainage. If pine bark is unavailable, coconut coir can substitute. Large gravel in the pot’s base can prevent waterlogging. Include a controlled-release fertilizer with occasional liquid feedings during the growing season for optimal growth. Regularly check moisture levels to avoid overwatering.

Fertilizing

To foster robust growth and abundant fruiting, mandarin orange thrives with balanced nutrition fertilizers. Apply a citrus-specific blend quarterly, increasing frequency slightly during the active growing season. Aim for a 1:1:1 NPK ratio, ensuring not to exceed label-recommended amounts to avoid root burn. Seasonal adjustments: slight reduction in winter, enhance in spring to support blossoming. Tip: Water mandarin orange before and after fertilization to aid nutrient absorption.

Pruning

In summer, cut back dense branches so they don’t compete with fruit for nutrients. Also prune any weak, infested, or infected branches. After harvesting the fruit in fall or winter, trim dead or leggy branches as well as those growing crosswise or too densely. This winter trimming will help air circulation and light reach the inner foliage, decreasing the opportunity for pests and diseases.

Propagation

Well-suited for cultivation in home gardens and orchards, mandarin orange can be propagated effectively through cutting. This method involves taking healthy, semi-woody stems from a mature tree and allowing them to root in a well-draining medium, which efficiently produces new individuals identical to the parent. For success, maintain high humidity and moderate temperatures, ensuring a nurturing environment for roots to develop. Additionally, the use of a rooting hormone can enhance rooting potential. Careful handling and monitoring will establish vigorous, fruit-bearing plants.

Transplanting

The prime window to transplant mandarin orange is from the onset of spring to mid-spring, as the awakening season favors root establishment. Prioritize well-draining, sunny locations for healthy growth. If needed, provide extra support to prevent transplant shock and keep mandarin orange content.

Overwintering

Mandarin orange, natively flourishes in a climate similar to its subtropical homeland, optimally enduring temperatures between 50° to 104°F. Winter adaptations involve storing energy to maintain core functions during cooler months. For successful over-wintering, gardeners must mimic these conditions indoors, providing enough sunlight and ensuring the temperature doesn’t drop below 50°F. A balance of water and humidity is also crucial to keep mandarin orange thriving through the winter.

Repotting

For the bushy mandarin orange, repot every 2-3 years to accommodate growth. Spring, the growth season start, is ideal to repot and invigorate. Select a container 2 inches larger to ease root expansion. Post-repot, use well-draining soil and water sparingly until new growth indicates successful adaptation. A sunny spot will help mandarin orange thrive after repotting.

III. Uses and Benefits

• Ornamental uses

Mandarin orange can be a delightful addition to the yard. This small tree produces a sweet, brightly colored citrus fruit whose flavor is a real treat and a welcome reward for the hard-working gardener. These trees are often planted in gardens for their hardiness, fruits, and their small size, which makes them an easy addition. Planting with marigolds, petunias, and borage may help keep away citrus pests.

• Culinary uses

Unlike other citrus fruits, mandarin flesh is not acidic. Sweet and fragrant, it can be eaten unprepared or used to make desserts and savoury dishes. The peel and skin can also be processed to make juices and liqueurs. Rich in vitamin C, the fruit is also said to have antiseptic and tonic properties.