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Description
Rhododendron Oldhamii, also known as Oldham’s Rhododendron, is a beautiful evergreen shrub native to Taiwan. It is a member of the Ericaceae family and is highly valued for its large, showy flowers and glossy, leathery leaves. This plant is a slow grower, but it can reach a height of up to 30 feet and a spread of 20 feet when fully matured. It blooms in late winter to early spring, producing clusters of pink or white flowers that can last for several weeks.
Taxonomic Information
| Domain | Eukaryota |
|---|---|
| Kingdom | Plantae |
| Phylum | Spermatophyta |
| Class | Magnoliopsida |
| Order | Ericales |
| Family | Ericaceae |
| Genus | Rhododendron |
Appearance
Rhododendron Oldhamii has large, leathery leaves that are dark green and glossy. The leaves are smooth on top and covered with small scales on the underside. The plant produces clusters of pink or white flowers with five petals that are funnel-shaped. Each flower can be up to 5 inches in diameter and has a sweet fragrance. The flowers bloom in late winter to early spring, and the plant can produce hundreds of flowers at once. The bark of the plant is smooth and light brown in color, with a few fissures as it ages.
Care Guide
Rhododendron Oldhamii requires specific care to thrive. Here are some tips to ensure its health:
Water:
The plant prefers moist soil and requires regular watering. However, it is important to avoid overwatering, as this can lead to root rot. Water the plant deeply once a week, and make sure the soil is well-draining.
Fertilization:
Use a balanced fertilizer specifically designed for acid-loving plants. Fertilize the plant in the spring after the flowers have faded and again in the fall.
Soil:
Rhododendron Oldhamii prefers acidic soil with a pH level of 4.5 to 5.5. The soil should be well-draining and rich in organic matter. Amend the soil with peat moss or compost to increase acidity and improve drainage.
Sunlight:
The plant prefers partial shade to full sun. However, it is important to protect the plant from hot afternoon sun, as this can cause leaf scorch.
Hardiness Zones:
Rhododendron Oldhamii is hardy in USDA zones 7 to 10.
Common Pests & Diseases
Rhododendron Oldhamii is susceptible to several common pests and diseases:
Pests:
- Aphids
- Spider mites
- Scale insects
Diseases:
- Phytophthora root rot
- Botrytis blight
- Powdery mildew
To prevent these issues, ensure the plant receives proper care and monitor it regularly for signs of infestation or disease. If an issue arises, treat it promptly with organic or chemical controls.
Habitat
Rhododendron Oldhamii is native to Taiwan, where it grows in the mountains at elevations of 4,000 to 8,000 feet. It prefers cool, humid climates with mild winters and moderate rainfall. The plant grows well in acidic, well-draining soil and partial shade to full sun.
Question and Answer
Q: How often should Rhododendron Oldhamii be pruned?
A: Rhododendron Oldhamii should be pruned in the late spring or early summer after flowering has ended. Prune back any dead or damaged branches and shape the plant as desired.
Q: How can I increase the acidity of the soil for Rhododendron Oldhamii?
A: You can increase soil acidity by adding organic matter such as peat moss or compost to the soil. You can also use a soil acidifier product formulated for acid-loving plants.
Q: Can Rhododendron Oldhamii tolerate full sun?
A: Rhododendron Oldhamii prefers partial shade to full sun. However, it is important to protect the plant from hot afternoon sun, as this can cause leaf scorch.
Q: How often should I fertilize Rhododendron Oldhamii?
A: Fertilize the plant in the spring after the flowers have faded and again in the fall using a balanced fertilizer specifically designed for acid-loving plants.
Related Plants
- Rhododendron catawbiense
- Rhododendron maximum
- Rhododendron ponticum
- Rhododendron yakushimanum
References
- “Rhododendron Oldhamii.” Missouri Botanical Garden, www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c987.
- “Rhododendron Oldhamii.” Pacific Horticulture Society, www.pacifichorticulture.org/articles/rhododendron-oldhamii/.
- “Rhododendron Oldhamii.” Royal Horticultural Society, www.rhs.org.uk/Plants/22198/Rhododendron-Oldhamii/Details.
