Metrosideros flowers scarlet in December, which is how it earned the name New Zealand Christmas bush. It is also one of the toughest plants you can put in a windy, salt-blasted coastal garden, and the compact hybrids now bred for pots and hedges have made it useful a long way inland as well. Here is how to grow it properly in Australian conditions.
Quick facts
| Detail | What to expect |
|---|---|
| Botanical name | Metrosideros excelsa, M. tomentosa, M. collina and hybrids |
| Mature size | 1m to 2m for the compact hybrids; 5m to 8m in Australian gardens for the tree forms |
| Position | Full sun; tolerates strong wind and salt spray |
| Soil | Free draining, sandy or gravelly soil preferred; poor tolerance of waterlogging |
| Water | Weekly while establishing, then very drought tolerant |
| Flowers | Red or orange brush-like blooms, mainly November to January |
| Climate zones | Coastal and temperate Australia, subtropical Brisbane, Mediterranean Perth; light frost only, to about -2C |
Choosing the right metrosideros
The genus splits neatly into two groups, and picking the wrong one is the single most common mistake.
Tree forms are the true pohutukawa. Metrosideros tomentosa and the excelsa types build a broad, gnarled, spreading crown with grey-felted leaf undersides, reaching 5 to 8m across most of Australia rather than the 15m-plus they manage on New Zealand cliffs. The variegated New Zealand Christmas tree is the same plant with cream leaf margins and a slightly slower, smaller frame. Both are superb foreshore and large-garden trees, but they develop surface roots and a wide canopy, so keep them at least 5m from paving, pipes and buildings.
Compact hybrids are the ones most home gardens actually want. ‘Little Ewan’ and ‘Firecracker’ sit around 1 to 1.5m and clip readily into a low hedge, while ‘Springfire’ reaches roughly 1.5 to 2m and flowers over a longer window than the tree forms, often with a second flush. These make excellent poolside and balcony plants, and they suit the same brief as many of the picks in our guide to the best plants for coastal gardeners.
For an exposed front line where wind is the limiting factor, metrosideros belongs on the same shortlist as the species in our roundup of plants for windy conditions. Its leathery leaves and dense twiggy growth shrug off the salt-laden gusts that shred softer foliage.
How to plant
Plant in autumn or early spring. In the subtropics you can plant almost year round, but avoid the peak of a Brisbane summer, when humidity encourages disease on soft new growth.
Drainage is the one non-negotiable. Metrosideros evolved on rocky headlands and sand dunes and will sulk, yellow and eventually collapse in soil that stays wet. Dig a hole twice the width of the pot and no deeper, and check drainage by filling it with water: if it holds water for more than a few hours, mound the plant 150 to 200mm above grade instead. Do not add heavy compost or manure to the backfill; a light mix of the native soil with a little coarse organic matter is better. Water in well, then mulch with a coarse chunky mulch kept 50mm clear of the trunk.
Space compact hybrids 60 to 80cm apart for a hedge, and give tree forms 6 to 8m from the next tree and from any structure. Stake only if the site is genuinely exposed, and remove the stake within 12 months so the trunk can build its own taper.
Ongoing care
Watering
Water twice weekly for the first six to eight weeks, then weekly through the first summer. After the first year an established plant is genuinely drought tolerant and rarely needs supplementary water outside extended heatwaves. Container plants are the exception and need watering two to three times a week through summer, because the free-draining mix they demand also dries quickly.
Feeding
Feed lightly. Metrosideros is adapted to low-nutrient coastal soils and reacts badly to overfeeding, producing soft leafy growth at the expense of flowers. One application of a native or low-phosphorus slow-release fertiliser in early spring is plenty. If you want more flowers, add sulphate of potash in late winter rather than more nitrogen.
Pruning
Prune immediately after flowering, in late January or February. The plant sets next season's buds on wood that matures over autumn, so cutting in winter or spring removes the flowers you were waiting for. Compact hybrids take a hard trim happily and respond by thickening up; tree forms need only the removal of crossing branches and any lower limbs you want lifted. Avoid pruning during long humid wet spells, because the flush of soft new growth that follows is the most vulnerable to disease.
Common problems and fixes
Myrtle rust. Metrosideros belongs to the Myrtaceae and is susceptible to myrtle rust, which shows as bright yellow powdery pustules on soft new growth and flower buds, mostly in humid coastal districts. Inspect new flushes, remove and bag affected growth rather than composting it, avoid overhead watering, and apply a fungicide registered for myrtle rust if the infection is repeat. Do not prune to force new growth during warm wet weather.
Yellow leaves and slow decline. Nearly always drainage. Check whether the plant is sitting in a bowl of wet soil, and if so lift and remount it on a raised bed of free-draining material.
Sooty mould and sticky leaves. Scale insects feeding on stems and leaf undersides. Treat with horticultural oil in mild weather and repeat after a fortnight; the black film weathers off once the insects are gone.
Distorted, silvered new growth. Thrips, most common in dry spring weather. Usually cosmetic, and a good soaking and a clean flush of growth resolves it.
No flowers. Three usual causes: too much shade, too much nitrogen, or pruning at the wrong time of year. Fix the pruning timing first, since it is the most common of the three.
Wind burn on a newly planted specimen. Established metrosideros handles wind superbly, but a fresh nursery plant grown under shadecloth needs a season to harden. Our notes on windburn on plants cover what to watch for.
Frequently asked questions
Does metrosideros really flower at Christmas in Australia?
Usually, yes. The tree forms peak from late November through January in southern Australia and can run a little earlier in Brisbane. The compact collina hybrids are less tied to the calendar and often flower from spring into early summer, with sporadic repeat flushes afterwards, so they give colour over a longer window.
Can metrosideros be grown as a hedge?
It makes an excellent one. The compact hybrids clip to anywhere between 80cm and 2m and hold a dense face better than most flowering shrubs, which is why they turn up so often in beachfront gardens. Plant 60 to 80cm apart, tip prune from the start, and time the main trim for straight after flowering to preserve the display.
How much frost will metrosideros take?
Light frost only. Mature plants handle brief dips to around -2C, and young plants less than that. In frost-prone inland districts such as the tablelands, Canberra or central Victoria, grow it in a pot in a protected north-facing spot rather than in open ground.
Is it safe to plant near a pool or a driveway?
The compact hybrids are ideal poolside because they are salt and chlorine splash tolerant, they do not drop large leaves, and their root systems are modest. The tree forms are a different matter: they build spreading surface roots and a broad crown, so keep them well back from paving, pipes and pool shells.
Will metrosideros grow in Melbourne or Perth?
Yes to both. Coastal Melbourne suits it well provided drainage is sharp, though hard frosts in outer suburbs will limit it. Perth is close to ideal, since the sandy soils and dry summers mirror its natural habitat, and it needs very little supplementary water there once established.
Ready to plant?
Metrosideros solves the hardest brief in coastal gardening: something that flowers, holds a shape, and does not mind wind or salt. Browse the range in our plants for coastal areas collection, or compare the compact forms against other options in hedging plants if you are planning a low seaside screen. If you are still shaping the wider design, our guide to planning a coastal feature garden is a good next read.
