The delavay Teaolive is a plant native to western and southwestern China that has fragrant, tubular white flowers that can perfume any garden. It was introduced to France by Abbe Delavay in 1890, which is where this species gets its name.
I. Appearance and Characteristics
Osmanthus delavayi is a species of flowering plant in the olive family Oleaceae. It is an evergreen shrub native to the Guizhou, Sichuan and Yunnan regions of southern China, and widely cultivated as an ornamental in temperate and subtropical zones elsewhere.
Osmanthus delavayi was discovered by the Jesuit missionary-botanist Fr Pierre Jean Marie Delavay in the mountains near Lan-kong in Yunnan province, China, in 1890. He sent seed to the French nurseryman Vilmorin. Though Maurice de Vilmorin distributed the seed among various correspondents, only a single seed germinated. All the O. delavayi of European gardens were cloned from this one source, until George Forrest obtained further supplies of seed in China after World War I.
Over several weeks in late winter to spring, Osmanthus delavayi bears fragrant flowers that are more prominent but less fragrant than Osmanthus fragrans, but substitutes for O. fragrans in less balmy gardens. The shrub currently holds an Award of Garden Merit from the Royal Horticultural Society which it first received in 1923 and has been praised by British garden writers. It is a garden staple in the east coast of Australia as far south as Tasmania. Its USDA Zone range is 7-9 (it can survive -15C), making it hardy in sheltered locations as far north as coastal New York and in the Pacific Northwest. It is a medium-sized shrub, eventually reaching up to 4 m (13 ft) tall and broad, though this may take up to 20 years, as the plant is relatively slow-growing.
II. How to Grow and Care
Delavay Teaolive thrives best in well-drained soil and partial to full sun exposure. Special care should be given to protect it from strong winter winds. Regular watering to maintain slight soil moisture is optimal, but delavay Teaolive is notably drought-tolerant once established, making its overall care straightforward.
Sunlight
Although the delavay Teaolive loves the sun, it will grow well in partial and full shade too. However, its growth habit will be much denser when given around 4-5 hours of sun a day. The exception is with variegated varieties – these tend to bleach out if they receive too much sunlight, so try growing them in a location that provides some afternoon shade. If you live in a region with hot, dry summers, you will need to provide your delavay Teaolive with some shade from the powerful midday sun.
Temperature
Delavay Teaolive is able to tolerate temperatures down to -18 ℃ but will need some protection from sub-freezing winds. The delavay Teaolive loves the heat, and is drought-tolerant once established, but doesn’t do well in low-humidity environments. In order to thrive, the plant needs a relative humidity of around 70%.
Watering
Delavay Teaolive thrives in a balanced moisture environment, showing moderate drought tolerance. Its native habitat experiences consistent rainfall, allowing it to adapt to watering once every 1-2 weeks. This plant’s evergreen nature allows it to retain water effectively throughout the year, making it an excellent choice for outdoor cultivation in areas with regular rain.
Soil
The delavay Teaolive will grow in just about any soil type, so long as it is well-draining. However, for your plant to really thrive, grow it in rich, fertile soil, with a pH leaning towards the alkaline side, around 5-7.5. Heavy clay soils can be amended with compost or coarse sand to improve drainage. Although the plant may grow in clay soil that hasn’t been amended, poor drainage will usually end up causing root rot and other diseases.
If you plan on growing your delavay Teaolive in a container, use a good quality potting mix or potting soil, or a 50/50 combination of the two. Mixing in some pumice can help to improve drainage even further.
Fertilizing
To boost Delavay Teaolive’s growth and flowering, apply a balanced fertilizer monthly during spring and summer, reducing to every two months in the fall. Prefer high-nitrogen fertilizers early in the growing season to enhance foliage development. Use the recommended dose on the label, ensuring even distribution around the plant’s base without contact with foliage. Avoid fertilization in winter when delavay Teaolive is dormant. Over-fertilization can lead to root burn – proceed with caution.
Planting Instructions
The delavay Teaolive is usually purchased as a potted plant, meaning that it can be planted throughout the year. However, fall is the best season for planting, as the winter months help to speed up root development. The best location for it in your garden would be somewhere sunny or partially shaded, with protection from cold winds. Each plant will also need about 2 m of space all around it.
To plant your delavay Teaolive, dig a hole that’s 2-3 times wider than the plant’s root ball, but no deeper. In fact, the wider the better! If you need to amend your soil before planting to improve drainage, remove 25% of the native soil and replace with composted cow manure or a good planting mix. Then, place your plant into the hole, ensuring that the top edge of the root ball is about 2.5 cm above the surface of the soil. Fill in the hole and tamp down, before deeply watering. You can also apply a phosphorus-rich fertilizer at this stage.
Pruning
The delavay Teaolive requires very little pruning, but this best done at the end of winter/early spring – if you prune too soon, the branches could end up freezing.
Begin by removing any diseased or dead branches, correctly disposing of any diseased plant material. To prune for shape, pick a few large, inner stems and cut them near to a main branch. This not only encourages good circulation within the plant, but also promotes new growth, giving the delavay Teaolive a fuller appearance. To prune a hedge, shear the plants each year, slightly lower than where you want it to be once its leaves grow in.
Propagation
Delavay Teaolive, a beautiful evergreen shrub known for its fragrant white flowers and lush foliage, thrives in well-drained soil and partial shade to full sun. For successful propagation, semi-hardwood cuttings taken in mature wood work best. These should be potted in a mixture of peat and perlite to encourage root development. Keep the soil moist and ensure high humidity and indirect light, which will help the cuttings to establish. Rooting hormone can enhance the chances of successful propagation, but it isn’t essential. Patience is key, as it might take a few weeks for roots to form.