Origin
The Metrosideros polymorpha Gaud. var. prostrata (Rock) St. John, commonly known as the dwarf '?hi'a lehua, is native to Hawaii. It is a subspecies of the larger '?hi'a lehua tree which is a dominant species in Hawaiian forests.
Common Names
The dwarf '?hi'a lehua is also known by other common names such as creeping '?hi'a and prostrate '?hi'a. These names describe the plant's growth habit, as it tends to grow horizontally along the ground, rather than vertically like its larger counterpart.
Uses
The dwarf '?hi'a lehua has several uses in traditional Hawaiian culture. Its wood is used to make tools such as digging sticks and spears, while its bark is used to make cordage and netting. The plant's flowers are also used in lei making, as they are a bright red color and hold cultural significance in Hawaiian traditions.
General Appearance
The dwarf '?hi'a lehua is a low-growing shrub that typically reaches a height of one to two feet. It has small, oval-shaped leaves that are a dark green color and slightly serrated along the edges. The plant produces bright red flowers that resemble a bottle brush, which bloom year-round. Its bark is a light brown color and has a rough texture.
Light Requirements:
Metrosideros polymorpha Gaud. var. prostrata, commonly known as the dwarf ohia, generally prefers full sunlight for optimal growth. The plant can tolerate some shade, but it may affect its growth and flowering. Therefore, it is best to plant the dwarf ohia in a location where it can receive at least six hours of direct sunlight per day.
Temperature Requirements:
The dwarf ohia is a hardy plant that can survive in a variety of temperature conditions. It can tolerate high temperatures but prefers cooler temperatures of around 70-80°F during the day and 60-70°F at night. Frost can damage the plant, so it is best to protect it during frosty conditions.
Soil Requirements:
The dwarf ohia thrives in well-drained soil that is rich in organic matter. It can grow in various soil types, including loam, clay, and sandy soils. It prefers slightly acidic soil with a pH range of 5.5 to 6.5. It is essential to ensure adequate drainage to avoid waterlogging, which can lead to root rot.
Cultivation
Metrosideros polymorpha Gaud. var. prostrata, commonly known as the Dwarf or Prostrate Ohia, is a low-growing plant that requires a well-drained and slightly acidic soil for optimum growth. The plant can easily thrive in full sun exposure or partial shade, but it prefers a mild humid climate.
The plant is commonly propagated using stem cuttings or seeds; however, stem cuttings are more effective. The best time to propagate this plant is during spring and summer, and it is advisable to avoid severe pruning when propagating.
Watering Needs
The Prostrate Ohia can be watered once or twice a week, depending on the prevailing weather conditions. During hot and dry seasons, it is important to water the plant regularly to prevent wilting. When watering, avoid waterlogging the soil to prevent root rot. Instead, water the plant until the soil is moist, and let it drain before re-watering.
Fertilization
The Prostrate Ohia will benefit from a slow-release fertilizer that contains essential nutrients like nitrogen, phosphorus, and potassium. Fertilize the plant once or twice a year, preferably during the growing season. Over-fertilization may cause nitrogen burn, leading to yellowing of the leaves.
Pruning
The Prostrate Ohia requires minimal pruning since it is a low-growing plant. However, you can prune the plant to improve its shape or remove any dead or diseased branches. If you want to control the spread of the plant, trim the lateral stems, since they tend to branch out and slow down the growth of the plant.
Propagation of Metrosideros polymorpha Gaud. var. prostrata (Rock) St. John
Metrosideros polymorpha Gaud. var. prostrata (Rock) St. John, commonly known as the creeping or prostrate '?hi'a, is a low-growing shrub that is native to Hawaii. This plant is often used as a groundcover and is an excellent choice for erosion control. It is also popular in rock gardens and as a container plant. Propagation of this plant can be achieved in various ways.
Seed Propagation
Propagation by seed is possible but not commonly used for Metrosideros polymorpha Gaud. var. prostrata (Rock) St. John. The seeds of this plant require special treatment to germinate. They need to be scarified or soaked in hot water before planting to break down the hard seed coat. After scarification, sow seeds in well-draining soil and keep them moist. Germination can take several weeks to months.
Cuttings Propagation
The most common method of propagation for Metrosideros polymorpha Gaud. var. prostrata (Rock) St. John is through stem cuttings. Cuttings should be taken during the plant's growing season. Using a sterile pair of scissors or pruning shears, take 4 to 6 inches in length stem cuttings from healthy plants. Remove the leaves from the lower half and dip the cut ends in rooting hormone powder. Plant the cuttings in well-draining soil and keep them moist. It takes about six to eight weeks for the roots to develop and for the cuttings to establish themselves.
Division Propagation
Propagation by division is another method that can be used on mature plants of Metrosideros polymorpha Gaud. var. prostrata (Rock) St. John. The plant's rootball must be divided into several sections, each with a portion of the plant's crown and roots attached. Each section can be potted up separately or planted directly in the garden.
Air Layering Propagation
Air-layering is a method that can take place on a matured part of the plant. Make a cut just below a stem or branch's node where the leaves attach. Scrape off the bark about an inch above the cut to expose the green layer underneath. Dust rooting hormone powder over the exposed green layer of the stem. Wrap damp sphagnum moss around the wound and then cover it with plastic wrap. In about two months, roots will begin to grow in the damp sphagnum moss. When this occurs, cut the stem below the rooted moss and plant it in soil.
Disease and Pest Management for Metrosideros Polymorpha Gaud. Var. Prostrata (Rock) St. John
Metrosideros Polymorpha Gaud. var. prostrata (Rock) St. John, commonly known as the Creeping ‘?hi‘a, is a unique plant that is native to Hawaii. This species is susceptible to certain diseases and pests. Here, we discuss the common diseases and pests that might affect the plant and suggest ways to manage them.
Common diseases
One of the most common diseases that affect this plant is the Rapid ‘?hi‘a Death (ROD) disease. This disease is caused by two species of fungi, Ceratocystis lukuohia and Ceratocystis huliohia. The fungus attacks the tree’s vascular system, leading to wilting and eventual death of the plant. Once the disease occurs, there is no cure. Therefore, prevention is the best approach.
Pest management
This plant is also at risk from several pests. One of the most damaging pests is the Japanese Beetle (Popillia japonica). This pest feeds on the plant's leaves, flowers, and fruits. To manage this pest, use a combination of physical and chemical controls. You can handpick the beetles or use a pyrethrin-based insecticide as a last resort.
The black twig borer (Xylosandrus compactus) is another pest that attacks “?hi‘a.” It can bore into the stems, causing wilting and death. This pest can be managed using stem injections of specific insecticides.
The Erythrina gall wasp (Quadrastichus erythrinae) is a serious pest of this plant in Hawaii. This pest feeds on the plant's leaves, flowers, and fruits and can cause significant damage. To manage this pest, remove infested plant parts and spray with an insecticide such as Clorpyrifos.
Conclusion
Metrosideros Polymorpha Gaud. var. prostrata (Rock) St. John is susceptible to several diseases and pests. Prevention is the best approach for the diseases, while a combination of physical and chemical controls can be used to manage pests. Proper plant care and regular monitoring for signs of disease or pest activity can help maintain plant health and prevent loss.
