Metrosideros

( met - row - sih - DEH - rohs )

At-A-Glance Information

This genus of flowering evergreen trees, shrubs, and vines includes species commonly grown for their attractive foliage and showy flowers. These trees perform best when grown in coastal regions and tolerate both wind and salty sea spray. These Pacific natives make great specimens, shade trees, and background trees for many types of landscapes. They are cultivated for their showy flowers, and are commonly used as street or park trees, and also have found a place in home gardens.

metrosideros Species and Varietals

The genus Metrosideros includes 60 species and is a member of the plant family Myrtaceae. The plants in this genus are closely related to those in Eucalyptus, Melaleuca (Tea Tree), Callistemon (Bottlebrush) and Syzygium (Clove). The genus name is derived from the Ancient Greek words for heartwood (metra) and iron (sideron). The best growing zones for Metrosideros vary depending on the species. For more information, see the following descriptions. To find your zone, click here: Zone Map.

Metrosideros collina (Vuga, Anume, Ohio Lehua)
This species grows well in USDA hardiness zones 9-11 or Sunset growing zones 16, 17, 23, and 24 and is native to Hawai'i. It has a somewhat shrubby, upright growth and produces powder-puff shaped red blooms in spring and early summertime. It is useful as a flowering hedge. Cultivars of this species include 'Spring Fire' (8-12 feet tall and 4-6 feet wide, with orange-red blooms and gray-green leaves), and 'Fiji' (to 2 feet tall and wide, with red flowers and copper new leaves).

Metrosideros elegans
Endemic to New Caledonia, these trees produce yellow Bottlebrush-type flowers. They are sometimes epiphytic plants at first, until they find an area of soil to sink roots into, and can then form large shrubs or trees. These plants are not widely available in the plant trade and have no common name. This species grows well in USDA hardiness zones 10 and 11.

Metrosideros excelsia (New Zealand Christmas Tree, Pōhutukawa)
This species grows well in USDA hardiness zones 9-11 or Sunset growing zones 16, 17, 23, 24, H1 and H2 and is native to New Zealand. These trees reach 30 feet tall or more, and spread as wide as they are tall. Lower branches should be pruned off if a tree form is desired. Leaves are dark green above, wooly underneath. These are useful as lawn or street trees. Variety 'Aurea' has yellow flowers and variety 'Gala' has leaves centered with yellow and dark red flowers with gold-tipped stamens. This species is considered invasive in South Africa.

Metrosideros operculata
Endemic to New Caledonia, this species usually grows as a shrub that reaches about 10 feet tall, but is also seen as a small tree that tops out around 33 feet. Stems are square and leaves are stiff and pointed. Flowers can be white, pink or red, and carry between 50 and 120 stamens.

Metrosideros stipularis (Tepu, Trepu, Tepual)
These plants are native to southern South America (Chile and Argentina), where they grow in wet, boggy microclimates. Flowers are white and bloom in summertime (January through March in their native range). They reach between 13 and 25 feet tall when mature, forming a shrub or tree. Wood has a high energy content, and is widely used as firewood. This species is suited for growing in USDA hardiness zones 8 and 9.

Metrosideros villosa (Metrosideros kermadecensis) (Dwarf Pōhutukawa, Tahitian Christmas Bush, Tahitian Rātā)
This species is native to New Zealand and grows well in USDA hardiness zones 10 through 11 or Sunset growing zones 16, 17, 23, 24, H1 and H2 and forms a compact shrub 3 feet tall and wide with orange-red flowers that bloom in springtime and sporadically through summer. Remove seed heads after flowers fade to discourage reseeding and encourage rebloom. Cultivars include 'Tahitian Sunset' (with cream and pink variegated foliage) and 'Tahiti' (with silver-green leaves and orange-red flowers). This species is considered invasive in New Zealand (outside of its native range) and Hawai'i.

Caring for Metrosideros

Choose a spot in the landscape that receives full sun; they will do best when they receive between 6 and 8 hours of direct sun each day. Most species can grow to be quite large, so ensure that the space you are choosing to plant Metrosideros is large enough to accommodate its mature size, which can be up to 30 feet tall with an equal spread. If planting Metrosideros shrubs as a hedge plant, space them between 3 and 5 feet apart for best coverage and airflow. Soil should be well-draining and slightly acidic to neutral (with a pH of between 5.5 and 7.0). These trees and shrubs do not like to have their feet wet; if soils are compacted or clayey, it is recommended to amend the planting site with plenty of sand and/or organic material to avoid waterlogged conditions. Apply a thick layer of mulch around the base of trees and shrubs, ensuring that it stays a few inches away from the trunk. This will help to suppress weed growth, increase soil moisture retention, and help to regulate soil temperatures. Water new plantings regularly to help form a strong root system. Once established, these trees are relatively drought-tolerant, but still benefit from occasional deep waterings during the warmest, driest months of the year. Water at the base of the tree to avoid wetting foliage.

Apply organic compost around the base of these trees and shrubs each year in springtime to help support the season's growth and flowering. Metrosideros plants are not heavy feeders, and do not typically need any more feedings. However, if trees or shrubs seem to be struggling or not flowering well, they may benefit from a feeding with a slow-release, balanced fertilizer in spring when the growing season begins. Choose a fertilizer that is balanced (10-10-10, for example) and slow-release. Avoid over-fertilizing these plants, as they will produce excessive foliage growth at the expense of flowering. The best time to prune these trees is after they finish flowering in late summertime. Prune to shape and remove dead, damaged, diseased, or crossing branches. For tree varieties, make sure to prune young specimens so that they form a strong central leader. For plants grown as shrubs, cut back excessive growth the maintain a compact shape. These trees and shrubs are considered very long-lived, and can survive for hundreds of years in the landscape before needing to be replaced.

Caring for Metrosideros in Containers
Metrosideros shrubs and trees do very well in the ground, but can also be grown in containers; dwarf cultivars such as 'Tahiti' or 'Fiji' are suited for growing in containers. Choose a container that is at least a few inches wider and deeper than the nursery pot or root ball. When mature, these plants will require a sturdy container that is at least 16 to 20 inches wide. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away. Fill with a well-draining potting mix amended with organic material and perlite, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly as the plant establishes itself in its new home. Once established, waterings can be lessened. Berberis plants grown in containers will need more frequent irrigation than those grown in the ground. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch. Prune to remove dead, damaged, or diseased foliage at any time during the growing season. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that it needs to be potted up; choose a slightly larger container and repot.

Propagation

Metrosideros can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your tree, follow the instructions below:

Propagating Metrosideros by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 4-6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Metrosideros by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. Seeds are contained inside of pods produced by trees, and are very tiny, so be careful not to lose too many while handling them. The seed capsules are typically ready to be harvested for seeds in summer and early fall.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Metrosideros trees produce hard pods that contain numerous small seeds.

Metrosideros seeds are very small, and are typically yellow-orange to tan in color.

Problems and Pests

Certain Metrosideros species are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Although these trees are relatively pest and disease free, they do suffer from time to time from the following issues: