Rimu
Dacrydium cupressinum
Dacrydium cupressinum, commonly known as rimu or red pine, is an evergreen conifer among New Zealand's native trees native to New Zealand. It is the country's most common native conifer and can be found across the North, South, and Stewart Islands. It typically grows to 35 meters (100 feet) in height, but can reach up to 60 meters (200 feet) with a stout trunk up to 2 meters (6 feet 7 inches) in diameter. Rimu has an estimated lifespan of 600-800 years, with some specimens living as long as 1,200 years. The tree is characterized by its drooping and hanging foliage. Young trees have a narrowly conical crown with long, thin, pendulous branches, while mature trees develop a more rounded crown with spreading branches and drooping branchlets. The bark is dark brown or gray, stringy, and peels off in large, thick flakes. Juvenile leaves are slender, 4-7 mm long, and can vary in color from dark green to bronze-green, red-green, or orange. Adult leaves are smaller, 2-3 mm long, scale-like, and more appressed to the stem. Dacrydium cupressinum is dioecious, meaning individual trees are either male or female. Pollen cones are typically 7-10 mm long, and the fruits, which take over a year to mature, are most commonly seen between February and May. The mature podocarpium is red, and the seed is deep bluish-black and egg-shaped. It is a dominant or co-dominant emergent species in mixed conifer or conifer-angiosperm forests at low to middle elevations, up to 700 meters above sea level. These forests are typically warm temperate evergreen rainforests with high year-round precipitation. Rimu holds significant importance in Mori culture and was historically used for various medicinal purposes. Its reddish-brown timber was also highly valued for general construction, furniture, and flooring.
Plant Description
Botanical Features
Dacrydium cupressinum, commonly known as Rimu or Red Pine, is a large evergreen conifer native to New Zealand and the country's most common native conifer. It can grow to about 35 meters in height, but can reach up to 60 meters with a stout trunk up to 2 meters in diameter, and has an estimated lifespan of 600-800 years. The tree is characterized by its drooping and hanging foliage; juvenile trees have a narrowly conical crown with long, thin, pendulous branches, while mature trees develop a more rounded crown with spreading branches and drooping branchlets. The bark is dark brown or gray, stringy, and peels off in large, thick flakes. Juvenile leaves are slender, 4-7 mm long, and can vary in color from dark green to bronze-green, red-green, or orange. Adult leaves are smaller, 2-3 mm long, scale-like, and more appressed to the stem. It is dioecious, with male and female cones on separate trees. Female trees bear highly modified fruit with a red, fleshy receptacle and a deep bluish-black, egg-shaped seed. It is a dominant or co-dominant emergent species in mixed conifer or conifer-angiosperm forests at low to middle elevations, typically in warm temperate evergreen rainforests with high year-round precipitation.
Quick Facts
| Scientific Name | Dacrydium cupressinum |
|---|---|
| Height | 30-50 m |
| Spread | 10-15 m |
| Water Needs | Moderate to high |
| Light | Full sun to part shade |
| Frost Tolerance | Good |
| Salt Tolerance | Poor |
| Growth Rate | Slow |
| Lifespan | Very long (1000+ years) |
Climate Best Suited to
Rimu (Dacrydium cupressinum) thrives in cool, moist conditions with consistent rainfall throughout New Zealand. It adapts well to typical New Zealand growing conditions with appropriate care and positioning.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Whangārei | Ideal |
| Auckland | Ideal |
| Hamilton | Ideal |
| Tauranga | Ideal |
| Rotorua | Ideal |
| Gisborne | Ideal |
| New Plymouth | Ideal |
| Napier | Ideal |
| Whanganui | Ideal |
| Palmerston North | Ideal |
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Ideal |
| Dunedin | Ideal |
| Invercargill | Ideal |
Natural Habitat
Rimu (Dacrydium cupressinum), New Zealand's most common native conifer, is a majestic tree found throughout the North, South, and Stewart Islands. Its natural habitat primarily consists of lowland to lower montane forests, typically at elevations up to 700-950 meters above sea level. Rimu is a dominant or co-dominant emergent species in mixed conifer or conifer-angiosperm forests, which are characterized as warm temperate evergreen rainforests with high year-round precipitation. It thrives in these moist, sheltered conditions, contributing significantly to the forest canopy. While widespread, its distribution is less common or even absent in parts of the eastern South Island. Historically, extensive rimu forests were a prominent feature of the New Zealand landscape, though deforestation has significantly reduced their extent in some areas, such as the Banks Peninsula.
Plant Conservation
The conservation status of Dacrydium cupressinum, commonly known as Rimu, presents a nuanced picture.
According to the IUCN Red List assessment in 2013, the species is classified as "Least Concern," with a stable population trend. However, some sources indicate a more precarious situation. MyNativeForest classifies Rimu as a "threatened species," noting a dwindling population and habitat erosion. The New Zealand Plant Conservation Network and Zealandia Te Māra a Tāne also state its current conservation status as "Not Threatened" (as of 2023 for NZPCN). Despite this, they highlight that as a forest type, Rimu has been significantly reduced due to widespread logging, with very few intact rimu-dominated forests remaining in the North Island.
Rimu is now a protected species in New Zealand, and logging for timber is prohibited on public land, though some selective felling is permitted in sustainably managed private forests.
Growing Requirements
Soil Requirements
Rimu (Dacrydium cupressinum) performs best in well-draining soil that retains adequate moisture. Like most New Zealand natives, it prefers soils that don't become waterlogged but maintain consistent moisture levels. Good drainage is essential for healthy root development.
- Well-draining soil essential for healthy growth
- Prefers consistent moisture without waterlogging
- Adapts to various soil types with good drainage
- Benefits from organic matter incorporation
- Mulching helps retain moisture and suppress weeds
Light Requirements
Rimu (Dacrydium cupressinum) performs well in full sun to partial shade conditions. Like many New Zealand natives, it adapts to various light conditions but typically shows best growth and form in positions that receive adequate sunlight throughout the day.
- Full sun to partial shade positions
- At least 4-6 hours of direct sunlight daily
- Tolerates light shade in warmer climates
- Morning sun particularly beneficial
Water Requirements
Rimu (Dacrydium cupressinum) requires regular watering during establishment, typically for the first 1-2 years. Once established, it becomes more drought-tolerant but benefits from consistent moisture during dry periods. Avoid overwatering which can lead to root problems.
- Regular watering during establishment phase
- Moderate drought tolerance once established
- Consistent moisture during dry periods beneficial
- Avoid waterlogged conditions
- Mulching helps conserve soil moisture
Planting Guide
Growing a Rimu is a long-term commitment, but a deeply rewarding one. This slow-growing giant will eventually become a magnificent feature in any large garden or restoration project. To ensure your Rimu gets the best possible start, it is important to choose the right location and provide it with the care it needs in its early years.
Site Selection
- Light: Rimu prefers a spot with full sun or partial shade. In hotter, drier areas, a position with some afternoon shade is ideal.
- Soil: The soil should be cool, moist, and well-draining, with plenty of organic matter. Rimu is adaptable but dislikes waterlogged or very dry conditions.
- Shelter: Young Rimu are sensitive to frost and strong winds, so a sheltered position is essential for the first few years.
Planting Instructions
- Timing: Plant your Rimu in autumn or spring, when the soil is moist and the weather is mild.
- Planting: Dig a hole that is wider and deeper than the root ball. Gently loosen the roots before placing the tree in the hole. Backfill with soil, making sure the tree is planted at the same depth as it was in its container.
- Watering: Water in well after planting and keep the soil consistently moist, but not wet, for the first couple of years.
Ongoing Care
- Watering: Even established trees will appreciate a deep watering during long, dry periods.
- Mulching: Apply a generous layer of mulch around the base of the tree to help conserve moisture and suppress weeds.
- Pruning: Rimu requires little to no pruning. You can remove any dead or damaged branches as you see them.
Ecological Role
Rimu plays a significant ecological role in New Zealand's native ecosystems. It is considered a keystone species, providing essential habitat and food for a wide array of native birds and animals. The dense, conical crown and needle-like leaves of the rimu tree offer shelter and shade to the understory ecosystem. Its trunk and branches also support various epiphytes and hemi-epiphytes, and it hosts numerous insect species.
The fruit of the rimu is a crucial food source for many native New Zealand birds, including Kk, Kerer«, Bellbirds, and T««. Notably, it is a vital food source for the critically endangered flightless parrot, the kkp, whose breeding cycles are linked to the rimu's fruiting patterns. Birds that consume the fleshy fruit are instrumental in dispersing rimu seeds, thereby aiding in the regeneration and expansion of rimu forests.
Uses & Significance
Garden Uses
- Excellent for native plant gardens and restoration
- Suitable for naturalistic landscape designs
- Low maintenance once established
- Contributes to local biodiversity
- Attractive to beneficial native wildlife
Landscaping Uses
Rimu (Dacrydium cupressinum) is a magnificent evergreen conifer that brings a distinctive and majestic presence to any large landscape. As New Zealand's most common native conifer, its unique weeping habit, impressive size, and ecological value make it a highly sought-after tree for specific landscaping applications.
Key Landscaping Applications:
- Specimen Tree: Rimu's elegant, weeping form and eventual towering height make it an outstanding specimen tree for large gardens, parks, and expansive properties. It creates a powerful focal point and adds significant architectural interest to the landscape.
- Native Garden and Restoration Projects: An excellent choice for native gardens and ecological restoration, Rimu contributes significantly to local biodiversity. Its presence supports native wildlife, particularly birds that feed on its small, red fruits, aiding in seed dispersal and ecosystem health.
- Long-term Investment: While slow-growing, especially in its early years, Rimu is a long-lived tree that offers a rewarding investment for future generations. Its beauty and ecological benefits increase with age.
- Shelter and Screening: In appropriate settings, mature Rimu can provide effective shelter from wind and offer natural screening due to its dense foliage.
Due to its potential to reach impressive heights of 35 to 60 meters, Rimu requires ample space to thrive and is best suited for larger properties where its mature size can be accommodated without impacting structures or utilities. Young Rimu trees benefit from sheltered locations, especially during their establishment phase, to protect them from harsh winds and frost. Minimal pruning is generally required, focusing on removing any dead or damaged branches to maintain its natural, graceful form.
Seasonal Care Calendar
Spring
Spring is an active growth period for Rimu (Dacrydium cupressinum). New growth emerges and this is an ideal time for planting new specimens. Monitor soil moisture as temperatures warm and growth accelerates.
- Active growth period with new foliage development
- Ideal time for planting new specimens
- Monitor soil moisture as temperatures rise
- Apply organic mulch if needed
Summer
Summer is typically the main growing season for Rimu (Dacrydium cupressinum). Ensure adequate watering during hot, dry periods, especially for young plants. Established plants show good heat tolerance with appropriate care.
- Peak growing season with active development
- Monitor watering needs during hot weather
- Young plants need consistent moisture
- Established plants show good heat tolerance
Autumn
During autumn, Rimu (Dacrydium cupressinum) begins to slow its growth as temperatures cool. This is another good time for planting as conditions become more favorable. Reduce watering frequency but maintain soil moisture.
- Growth slows as temperatures moderate
- Good time for planting new specimens
- Reduce watering frequency gradually
- Maintain soil moisture without overwatering
Winter
Winter is typically a dormant period for Rimu (Dacrydium cupressinum), with minimal growth activity. Reduce watering but ensure plants don't completely dry out. Most New Zealand natives are cold-hardy and require minimal winter protection.
- Dormant period with minimal growth activity
- Reduce watering but avoid complete drying
- Generally cold-hardy in most New Zealand climates
- Minimal winter protection required
When to Prune and How Much
Rimu (Dacrydium cupressinum) generally requires minimal pruning to maintain its natural form and health. Most maintenance involves removing dead or damaged growth and light shaping if needed.
- Remove dead, damaged, or diseased growth as needed
- Light pruning to maintain shape if desired
- Prune after flowering if applicable
- Avoid heavy pruning which can stress the plant
- Use clean, sharp tools to prevent disease
- Most natives maintain good form without regular pruning
Always use clean, sharp tools when pruning to minimize disease risk. Native plants typically maintain their natural form well and often require less intervention than exotic species.
How to Grow Rimu
Rimu, New Zealand's most common native conifer, is a magnificent and long-lived tree, highly valued for its distinctive drooping foliage and beautiful reddish timber. While it is a slow-growing species, establishing a Rimu in your garden is a rewarding long-term investment, contributing to native biodiversity and providing a majestic focal point. It thrives in moist, well-drained soils and prefers sheltered locations, especially when young. Understanding its propagation methods is key to successfully growing this iconic species.
From Seed
Propagating Rimu from seed is the most common method, though it requires patience due to variable germination rates and slow initial growth. Collect fresh seeds from the small, red, fleshy fruits (podocarpium) when ripe, typically between February and May. Clean the seeds thoroughly to remove the fleshy part, as this can inhibit germination. Sow the fresh seeds in a well-draining seed-raising mix, lightly covering them. Maintain consistent moisture and provide cool, shaded conditions. Germination can be slow and erratic, often taking several months to over a year. Stratification (a period of cold treatment) can sometimes improve germination rates. Once seedlings have developed a few true leaves, they can be potted into individual containers and grown in a sheltered, moist environment for their first few years before planting out.
From Cuttings
Propagating Rimu from cuttings is generally more challenging and less reliable than from seed. Semi-hardwood cuttings can be attempted in late summer or early autumn from healthy, current season's growth. Cuttings should be about 4-6 inches long. Remove the lower foliage and, if desired, dip the cut end in a rooting hormone. Plant the cuttings into a well-draining, sterile cutting mix, such as a blend of perlite and peat. Maintain high humidity around the cuttings, perhaps by placing them under a plastic dome or in a propagator, and provide bottom heat to encourage root development. Keep the medium consistently moist but not waterlogged. Rooting can be slow and success rates are often low, making this method more suitable for experienced propagators.
Pests & Diseases
Rimu is a remarkably resilient tree, demonstrating strong resistance to most pests and diseases. Its longevity is a testament to its robust nature. However, it is not entirely immune, and certain organisms can impact its health, particularly in specific conditions or at different life stages.
Pests
- Seed Predators: The seeds of the Rimu are a valuable food source for a variety of native and introduced wildlife. Birds such as the kk and kerer«, along with bats and even weta, are known to predate the seeds. Introduced rats and mice can also have a significant impact on seed viability, affecting natural regeneration.
- Scale Insects: Rimu has a fascinating symbiotic relationship with scale insects. These insects feed on the tree's sap and excrete a sugary honeydew, which in turn attracts beneficial insects like ladybugs that help to control other pest populations on the tree.
- Wood Borers: While the living tree is largely resistant to insect attack, the sawn timber of Rimu, particularly the sapwood, is susceptible to the common house borer (Anobium punctatum).
Diseases
Rimu is not known to be susceptible to many diseases. However, it can be affected by a few fungal species.
- Armillaria species: The parasitic fungus Armillaria mellea is known to affect Rimu, and the native Armillaria novae-zelandiae is also commonly found on the tree. These fungi can cause root rot and can be particularly damaging to trees that are already stressed.
- Other Fungi: Other fungal species associated with Rimu include Ganoderma applanatum, Hypochnicium polonense, and Rigidoporus concrescens. These are typically found on dead or decaying wood and are not considered primary pathogens of healthy trees.
To minimize the risk of disease, it is always best practice to use clean, sharp tools when pruning, and to avoid causing unnecessary damage to the bark, which can create entry points for fungal spores.
Cultural Significance
Dacrydium cupressinum, commonly known as rimu, holds significant cultural importance in New Zealand for both Māori and early European settlers.
For the Māori, the Indigenous People of New Zealand, Rimu Is a Highly Valued Tree:
- Resource for tools and carvings: The durable and versatile timber was traditionally used for crafting essential tools, weapons (like long spears for defense), and intricate carvings.
- Medicinal uses: Māori utilized various parts of the rimu for medicinal purposes. The gum or sap was used as a styptic to stop bleeding, bark decoctions treated wounds, crushed inner bark pulp was applied to burns, and leaves were used for sores.
- Food source: The fruit of the rimu was an important food source during fruiting seasons, though harvesting it was often dangerous due to its location at the ends of branches.
- Pigment for tattoos (Moko): The heartwood of the rimu, when burned and ground with a grub called aawhato, was used as a pigment for traditional Māori facial tattoos (moko).
- Spiritual beliefs: Some Māori believed the wood could help ward off evil spirits, particularly at night.
- Canoe making: The Ngāpuhi tribe specifically used rimu timber for crafting canoes (waka).
For European Settlers, Rimu Also Played a Role:
- Timber industry: Rimu was once the most harvested timber in New Zealand, making up 58% of the country's total timber production between 1918 and 1930. It was prized for its durable and resilient texture and used for flooring, furniture making, wagon building, and interior paneling of trams and railway cars.
- Brewing: In 1773, Captain James Cook brewed the first native beer, known as "spruce beer," using the young tips of rimu branches. This beer was an effective way to prevent scurvy.
Bonus Tip
Rimu (Dacrydium cupressinum) is very slow in cultivation; avoid high-phosphorus fertilisers and instead mimic forest litter with a deep mulch of leaf mould or fine bark. Young trees appreciate wind shelter and filtered light - planting them under a light, temporary nurse canopy (such as mnuka/knuka) often produces straighter, denser leaders.
