Osmanthus fragrans ‘Xiaoye Fodingzhu’: Nature’s Fragrant Masterpiece

Osmanthus fragrans ‘Xiaoye Fodingzhu’, commonly known as Buddha’s Bead or Fodingzhu, is a remarkable cultivar of sweet osmanthus renowned for its exceptional fragrance and resilience. This evergreen shrub or small tree exhibits several distinctive characteristics that make it a prized selection among gardeners and horticulturists.

I. Basic Introduction

Fodingzhu (Osmanthus fragrans ‘Xiaoye Fodingzhu’) is an evergreen shrub or small tree belonging to the Oleaceae family. Its foliage consists of opposite, simple, and leathery leaves with entire margins, featuring glandular surfaces on both sides and distinct petioles.

The floral structure is bisexual, with plants being either dioecious or monoecious. The inflorescences are umbellate, clustered in leaf axils, and form short conical structures at branch terminals. Two bracts, fused at the base, accompany each flower cluster. The calyx is bell-shaped with four lobes, while the corolla is white or yellowish-white, bell-shaped, cylindrical, or urn-shaped, featuring four overlapping lobes in bud stage.

Although the pistils are typically degenerate in this cultivar, preventing fruit formation, the standard fruit of Osmanthus species is a drupe, oval or obliquely oval, with a hard or bony endocarp usually containing a single seed. The seed’s endosperm is fleshy, with flat cotyledons and an upward-pointing radicle. The basic chromosome number for the genus is x=23.

A unique feature of Fodingzhu is its ability to bloom in the first year from seedlings, with inflorescences concentrated at the tips of new shoots. The name “Fodingzhu,” meaning “Buddha’s Bead,” comes from the appearance of the flower buds just before opening, resembling tiny white pearls. This compact growth habit makes it particularly suitable for container cultivation.

II. Growth and Distribution

Distribution Range

Fodingzhu is a member of the Four Seasons Osmanthus group, a category known for extended blooming periods. This cultivar was successfully bred and began to be widely promoted in the late 1990s, quickly gaining popularity due to its unique characteristics.

Growth Habit

Fodingzhu demonstrates several notable growth characteristics:

1. Form: It is an evergreen small shrub with short, dense branches and vigorous growth.
2. Size: Two-year-old cuttings can develop into full spheres 40-50 cm in diameter.
3. Flowering period: Initial blooming begins mid to late August, peaks from early September to New Year’s Day, and continues until after the Spring Festival, resulting in a remarkable six-month flowering period.
4. Light requirements: Under full sun conditions, with proper pruning and fertilization, it blooms continuously.
5. Adaptability: It shows wide environmental tolerance, including light saline-alkaline soils (pH ≤ 7.5) and various adverse climatic conditions.
6. Pruning tolerance: The plant responds well to pruning, allowing for shaping and size control.

III. Morphology and Features

Fodingzhu exhibits a compact and attractive form:

1. Size: Heights range from 0.5 to 2.0 meters.
2. Crown: Dense and compact.
3. Leaves: Dark green with a prominent network pattern, long-elliptical, averaging 6.0 cm in length and 2.6 cm in width (length-to-width ratio ≈ 2.30). The leaf surface is concave, forming a ‘V’ shape, with serrated edges.
4. Flowers: Range from delicate milky yellow to pure white. The terminal inflorescences are unique and prolific.
5. Flowering period: Begins mid to late August, peaks from early September to the New Year or Chinese New Year, lasting approximately six months.
6. New growth: Shoots and young leaves are purple-red, creating an attractive contrast with mature foliage.
7. Fragrance: Highly aromatic, typical of sweet osmanthus but with its own distinct character.

Fodingzhu is also noted for its strong resistance to pollution, particularly to carbon monoxide (CO), sulfur dioxide (SO2), and hydrogen fluoride (HF).

This resilience, combined with its long blooming period, compact growth, and attractive foliage, makes it an excellent choice for urban landscaping, container gardening, and as a fragrant ornamental in various settings. Its ability to thrive and bloom under adverse conditions further enhances its value as a versatile and reliable plant for both public and private gardens.

IV. Cultivation Methods

Breeding

Nursery selection. The ideal nursery soil for Osmanthus should be well-drained sandy loam or light loam. If the soil is too heavy or clayey, incorporate sand to improve drainage and aeration. To prevent fungal diseases such as wilt and root rot, sterilize the soil with an appropriate fungicide during bed preparation.

Elevated cuttings beds are crucial for ensuring proper drainage. Experience has shown that water accumulation after rainfall can easily lead to rot, especially before the cuttings have established roots. Therefore, it’s essential to design beds with adequate drainage and promptly remove excess water.

Setting up propagation structures. The enclosed breeding system refers to a double-layered structure: a shade shed within a plastic tunnel. The optimal width for the cutting bed is 1.10 meters, with an effective utilization of 1.0 meter.

Create arches using sharpened bamboo pieces, inserted into the ground on both sides of the bed. The apex of the arch should be 0.5 meters above the bed surface. To maintain the bow shape and provide stability, secure the bamboo pieces together using thin bamboo strips or twine.

Ensure the plastic covering is tightly secured to the ground along the sides, leaving no gaps. However, the ends of the plastic tunnel can remain open to facilitate ventilation.

Place two layers of reed mats or shade cloth atop the plastic tunnel, extending to a height of 1 meter. Leave a 50-centimeter gap between the plastic covering and the reed mats to allow for air circulation and temperature regulation.

Additionally, install a single layer of shade material around the sides of the plastic tunnel to prevent direct sunlight exposure from the sides.

Ground planting

The optimal time for ground planting Osmanthus is early spring. Choose a planting site that offers full sun exposure, excellent drainage, and deep, fertile soil. Prior to planting, prepare a spacious planting hole, incorporate ample organic matter, and add some hardwood ash to adjust soil pH and provide micronutrients.

When transplanting, preserve the root ball intact to minimize transplant shock. After planting, water thoroughly to settle the soil around the roots. Once the plant shows signs of establishment, begin applying a balanced liquid fertilizer. During the active growing season (July-August), fertilize and water 1-2 times to support vigorous growth.

Before winter, apply well-decomposed compost as a mulch. In subsequent years, follow this fertilization schedule: apply a quick-release nitrogen fertilizer in late March to support spring growth, a balanced phosphorus-potassium fertilizer in July to promote flower bud formation, and organic fertilizer in October to build soil health and prepare for winter.

After each fertilization, water thoroughly and remove any weeds that may compete for nutrients. Implement a regular integrated pest management program to control diseases and pests. This comprehensive care regimen will promote rapid growth, abundant annual flowering, and intensify the fragrance of the blooms.

Bonsai

To cultivate a thriving Osmanthus bonsai with prolific blooms and intense fragrance, focus on five key aspects: appropriate soil selection, proper watering techniques, strategic fertilization, skillful pruning, and effective pest and disease management.

Soil composition: Osmanthus prefers slightly acidic soil with a pH range of 6.0-6.5. For container cultivation, use a well-draining mix consisting of 50% acidic components (such as pine bark or peat moss) and 50% inorganic materials (like pumice or akadama). This blend ensures adequate moisture retention while preventing waterlogging.

Watering regime: Implement the “two less, one more” watering strategy. Reduce watering before new growth emerges in spring and during periods of rainfall or high humidity. Increase watering frequency during dry spells in summer and autumn.

Maintain soil moisture at approximately 50% capacity. During the flowering period in autumn, be cautious of overwatering, which can cause blossom drop. In rainy weather, ensure proper drainage to prevent root rot.

Fertilization: After spring bud break, apply a diluted, balanced organic fertilizer every 10-14 days to promote vegetative growth and branching.

From July onwards, transition to a low-nitrogen, high-phosphorus fertilizer to encourage flower bud formation. Apply a dilute solution of well-rotted poultry manure or fish emulsion, or supplement with monocalcium phosphate at 0.5% concentration.

A final application of phosphorus-rich liquid fertilizer in early September will enhance bloom quality and fragrance. Insufficient fertilization, particularly phosphorus deficiency, results in sparse branching, reduced flowering, and diminished fragrance.

Pruning techniques: Osmanthus exhibits vigorous root development and strong budding potential. Mature specimens typically experience two growth flushes annually, in spring and autumn. To maintain a balance between vegetative growth and flowering, implement a bi-annual pruning regimen.

Perform the first pruning after autumn flowering, focusing on thinning dense growth and shortening elongated summer and autumn shoots, while preserving robust short branches evenly distributed along each lateral branch.

The second pruning should occur in early spring before bud break, removing weak, diseased, or pest-infested branches to improve light penetration and air circulation, thus promoting fuller flower bud formation.

Throughout the growing season, pinch back new shoots to redirect energy towards flowering. For bonsai specimens, aim for a compact form with a sturdy trunk and dense branching.

Repotting and winter care: Repot Osmanthus bonsai every 1-2 years in early spring, just before new growth begins. In colder regions, provide winter protection by moving the bonsai to an unheated structure that maintains temperatures above 0°C (32°F).

During winter dormancy, keep the soil slightly moist but not wet. After the spring equinox, gradually reintroduce the bonsai to outdoor conditions, placing it in a well-ventilated, sunny location to support healthy growth and abundant flowering in the coming season.

V. Propagation Methods

The Crown of Thorns (Euphorbia milii) can be propagated through cuttings or grafting.

Cuttings

Stem cuttings are the most common and effective method for propagating Crown of Thorns. This process should be done during the active growing season, typically in spring or early summer.

1. Timing for Cuttings: The ideal period for taking cuttings is from late spring to early summer (May to June) when the plant is actively growing. This timing ensures that the cuttings have enough energy to root and establish themselves.
2. Choice and Treatment of Cuttings:
   • Select healthy, non-flowering stems that are 4-6 inches (10-15 cm) long.
   • Use clean, sharp pruning shears to make the cut just below a leaf node.
   • Remove the lower leaves, leaving only 2-3 pairs of leaves at the top.
   • Allow the cut end to callus for 24 hours before planting to prevent rot.
   • Dip the cut end in rooting hormone to encourage faster root development.
3. Planting and Care:
   • Plant the cuttings in a well-draining potting mix, such as a combination of peat moss and perlite.
   • Insert the cutting about 1-2 inches (2.5-5 cm) deep into the soil.
   • Water lightly and place in a warm, bright location, but out of direct sunlight.
   • Maintain high humidity by covering with a clear plastic bag, but remove it daily for air circulation.
   • Roots typically form within 3-4 weeks. Gently tug on the cutting to check for resistance, indicating root formation.
   • Once rooted, gradually acclimate the new plant to normal growing conditions.

Grafting

While grafting is possible for Crown of Thorns, it is less common and generally unnecessary due to the ease of propagation by cuttings. However, grafting can be used to create unique specimens or to propagate variegated cultivars that may not root well from cuttings.

1. Rootstock Selection: Use a healthy, established Crown of Thorns plant as the rootstock. Ensure it is disease-free and vigorous.
2. Scion Preparation: Select a healthy stem from the desired variety, about 3-4 inches (7.5-10 cm) long with at least two leaf nodes.
3. Grafting Process:
   • Use the wedge (cleft) graft method, which is most suitable for succulent plants like Crown of Thorns.
   • Make a vertical cut about 1 inch (2.5 cm) deep in the center of the rootstock’s cut surface.
   • Shape the base of the scion into a wedge that fits snugly into the cut on the rootstock.
   • Insert the scion, ensuring the cambium layers of both rootstock and scion align on at least one side.
   • Secure the graft with grafting tape or parafilm, being careful not to apply too much pressure.
4. Aftercare:
   • Keep the grafted plant in a warm, humid environment out of direct sunlight.
   • Maintain slightly moist soil, but avoid overwatering to prevent rot.
   • The graft should heal within 2-3 weeks. Once new growth appears on the scion, gradually acclimate the plant to normal growing conditions.

Remember, when propagating Crown of Thorns, always wear protective gloves and eye gear, as the milky sap can cause skin irritation and is toxic if ingested. Proper care and attention during the propagation process will result in healthy new plants that can thrive for years to come.

VI.Pest Control

Osmanthus trees are susceptible to various diseases and pests including anthracnose, brown spot disease, gray mold, leaf blight, algal leaf spot, sooty mold, and pests such as scale insects, bagworms, spiky moths, leafhoppers, and osmanthus leaf cicadas.

Timely application of appropriate pesticides is crucial for prevention and control.

Brown Spot Disease

Brown spot disease, caused by a fungal pathogen, primarily affects osmanthus leaves. Initial symptoms appear as small yellow spots that develop into nearly circular or irregular lesions, ranging from yellow-brown to gray-brown in color, with diameters of 2-10mm.

The lesions are typically surrounded by a yellow halo, and the leaf surface may exhibit numerous small black dots, which are the fungal conidiophores and conidia.

As the disease progresses, lesions may coalesce into larger areas, causing leaf necrosis, though they do not typically cross leaf veins. The pathogen spreads via wind, rain, and irrigation water.

The disease cycle begins in March, with peak infection occurring from April to October, and declining after October. High temperature and humidity promote disease development, with older leaves being more susceptible.

Generally, red osmanthus varieties show higher resistance to this disease compared to golden or silver osmanthus.

Prevention and Control Methods:

1. Winter sanitation: Remove and destroy diseased plant debris and fallen leaves promptly.
2. Pruning: Trim leaves of newly planted seedlings, and spray with a 0.1% potassium permanganate solution when transplanting from heavily infected areas.
3. Cultural practices: Improve water and fertilizer management, emphasizing humus and potassium fertilizers to enhance plant resistance. Ensure good ventilation and lighting in the growing environment. Avoid overhead irrigation and minimize plant wetness during peak disease periods.
4. Pest management: Control sap-feeding insects like scale insects and aphids promptly.
5. Chemical control:
   • Preventive: Before moving plants indoors in late autumn, apply two sprays of 70% Mancozeb (1:500 dilution).
   • Curative: For outbreaks, use 90% Carbendazim (1:500) or 50% Polyram (1:500).
   • During disease periods, apply Bordeaux mixture (1:2:100-200), 50% Benomyl (1:1000-1500), Prochloraz (1:500), or 50% Thiram (1:600).

Leaf Blight

Leaf blight, also known as necrotic spot disease, is a significant osmanthus pathogen primarily affecting leaves. Symptoms typically begin at leaf tips and edges, with small light brown spots that enlarge into circular or irregular shapes.

Affected areas may curl and crack, often coalescing to cover one-third to half of the leaf in a grayish-brown color with green margins. In advanced stages, small black fruiting bodies appear on the lesions.

The disease can occur year-round, potentially causing extensive leaf desiccation. It is exacerbated by high temperature and humidity, poor ventilation, and weakened plant health. Peak infection typically occurs from July to November, with the pathogen spreading through wind and rain.

Prevention and Control Methods:

1. Sanitation: At the end of autumn and early winter, thoroughly remove and destroy (burn or deep bury) diseased leaves to reduce overwintering inoculum.
2. Nursery management: For transplants or newly introduced plants, remove diseased leaves and incinerate them. If necessary, treat seedlings with 50% carbendazim (1:500) or 0.1% potassium permanganate solution before transplanting.
3. Cultural practices: Enhance plant management by increasing phosphate and potassium fertilization, regular soil cultivation and weeding, preventing soil crusting or waterlogging, and maintaining appropriate irrigation during hot, dry periods to boost plant resistance.
4. Chemical control: In severely affected areas, initiate a spray program in late June, applying one of the following every two weeks for 3-4 applications:
   • 70% mancozeb (1:500)
   • 75% thiophanate-methyl (1:800)
   • Bordeaux mixture (1:2:100)
   • 25% propiconazole (1:5000), reapplied every 48 days

Sooty Mold

Sooty mold typically develops during periods of high temperature and humidity, especially in poorly ventilated, damp environments. It manifests as a gray-black powdery substance or film on leaf surfaces and dry branches.

This condition is caused by various fungi growing on the honeydew excreted by sap-feeding insects such as aphids, scale insects, and mealybugs. The sooty layer not only diminishes the ornamental value of osmanthus but also interferes with leaf photosynthesis, leading to poor plant growth, premature leaf yellowing, and wilting.

Prevention and Control Methods:

1. Cultural practices: Enhance pruning to improve air circulation and light penetration within the plant canopy.
2. Pest management: Promptly control sap-feeding insects like aphids, scale insects, and mealybugs.
3. Hygiene: Regularly rinse leaves of potted plants with water to remove honeydew and sooty mold.
4. Chemical control: In early stages of infection, spray branches and leaves with one of the following:
   • 50% thiram suspension (1:500)
   • 50% carbendazim (1:800)
   • 75% thiophanate-methyl (1:500)

Iron Chlorosis

Iron chlorosis in osmanthus is typically caused by alkaline soil conditions, often exacerbated by building debris not thoroughly removed from the planting site. In alkaline soils, iron exists as insoluble iron hydroxide, which is unavailable for root uptake, leading to iron deficiency.

Mild deficiency symptoms include interveinal chlorosis of young leaves, while veins remain green. Severe deficiency results in chlorosis of both new and mature leaves, stunted growth of new leaves, and the development of yellow-brown spots on older leaves.

This condition significantly impairs plant growth, flowering, aesthetic value, and flower yield.

Prevention and Control Methods:

1. For mild deficiency:
   • Apply 0.5% ferrous sulfate solution to roots
   • Foliar spray with 0.2% ferrous sulfate solution
2. For severe deficiency:
   • Apply 20-40g of chelated iron (Fe-EDTA) to the soil around each plant
   • Foliar spray with 0.1% chelated iron solution
3. Preventive measures:
   • During spring growth, apply biweekly foliar sprays of 0.2% ferrous sulfate
   • When preparing potting soil, adjust pH to below 6.5 using 0.5% ferrous sulfate solution

Dry Rot

Dry rot primarily affects newly transplanted, large osmanthus specimens. It often results from mechanical injuries during transplanting, transport, or accidental impacts that damage the bark of the main stem or large branches.

If left untreated, these wounds can become entry points for wood-rotting fungi and bacteria, leading to localized rot, wood exposure, or tumor formation. Severe cases can result in poor growth, massive defoliation, branch dieback, and potentially plant death.

Prevention and Control Methods:

1. For small wounds: Promptly apply a wound healing agent.
2. For small wounds with minimal rot: Clean the area to expose fresh wood and cambium, then apply a wound healing agent.
3. For large, old wounds: Clean the exposed wood and regularly apply a litharge-sulfur compound or a two-component “marble glue” colored to match the fresh wound.
4. For hollow main stems: Carefully remove rotten wood without damaging the barrier layer between decayed and healthy wood. Fill the cavity with polyurethane foam.

VII. Value and Other Aspects

The Buddha’s Cap Pearl osmanthus variety demonstrates strong resistance to pollution, including tolerance to CO, SO2, and HF. It can thrive and bloom under various adverse environmental conditions.

Widely recognized as an excellent osmanthus cultivar, it excels in greening, beautification, fragrance production, and resistance to cold and environmental stressors.

This variety is versatile in landscape applications, suitable for:

• Small area plantings and clusters to create fragrant flower blocks
• Keynote species in hedges and highway greening projects
• Greening industrial sites, educational campuses, healthcare facilities, parks, and other public spaces

Its adaptability and ornamental qualities make it a valuable choice for diverse urban and rural landscaping needs.