Farm Forestry New Zealand

Radiata pine tolerates a wide range of site conditions.

Planting

Radiata planting stock is available from many commercial nurseries, either bare-rooted or containerised. Most radiata pine planting stock is raised from seed and sold bare-rooted.

Cuttings are more expensive than seedlings and may have slightly less vigor, but generally offer better form, lighter branching and less risk of toppling. Planting stock is rated (and priced) on the predicted characteristics of the tree it has been bred to produce. The current rating system is GF Plus.

Price per tree should range from $0.50 - $1.00 for 1 year-old forestry stock (2020 prices).

Plant bare-rooted stock in winter. Containerised stock can be planted from autumn to spring.

Radiata pine dislikes waterlogged ground, shade and frost. It’s also best to avoid high fertility sites where the trees grow excessively fast with few roots and are subject to windthrow. On fertile sites trees also grow bigger branches and are more subject to breakages and poor form. The best sites for growing good quality trees are lower fertility well-drained sites.

Spacing

Plant radiata at stockings of 600-1500 stems per hectare, or between 2 and 3 times the planned final crop stocking to allow choice in selecting the final crop trees. Spacings of 2 x 5 metres, 2.5 x 4 metres, or 3.16 x 3.16 metres will all give 1000 trees per hectare.

Releasing

Radiata pine establishes much faster with good weed control. Release spray only once after planting, once weeds begin to regrow. Spray-releasing dramatically increases growth rate of radiata pine but this increases the risk of windthrow, especially during the first to third winters.

See Successful establishment of tree seedlings »

Grazing/Browsing

Stock should be fenced out for at least six years or until rough bark develops.

Young radiata pine seedlings are palatable to hares and rabbits. They will slice off trees near ground level at a 45 degree angle, killing them.

Young radiata may be palatable to possums which should be controlled with poison, trapping or shooting.

Pests and diseases

Radiata pine can be susceptible to root-rot if the ground becomes waterlogged. It is also subject to various needle diseases. Higher elevation, wetter sites are subject to red needle cast, whereas humid, sheltered inland sites can be subject to dothistroma and cyclaneusma.

See Pests and diseases of radiata pine »

Radiata pine is wind hardy and can grow on thin eroded soils, so suits steepland sites. Grown for timber it may be pruned and thinned for clearwood, or kept at higher stockings for framing timbers. There is a regional market for radiata pine woodchips which can add value to any harvest, and carbon credits can provide an early income. Note radiata seed can be spread by the wind and it will slowly invade both open country and established vegetation if it is not controlled by browsing.

Suitability for steep slopes: Radiata has been extensively planted on erodible hill country where it provides effective erosion control until it is clearfelled, when there is a window of risk and erosion can occur. The short rotation length and clearfell harvesting practice is almost universal because the economics of harvesting commodity logs do not justify continuous cover harvesting.

Pruning

Radiata will branch vigorously and if grown for clearwood will require pruning. Higher initial stockings are recommended to control branch size if growing for framing timber.

A typical clearwood pruning regime is: Age 2-3 years, sail prune if toppling is a threat (i.e. take out some branches to reduce the wind thrust on the tree). Remove double leaders. When the trees are about 5 m high, prune the trunk to a diameter of about 10 cm leaving 2.5 to 3 metres of green crown. This is the ‘first lift.’ Remove double leaders in the crown and possibly cut any remaining large branches back to less than half their length. When the tree height is about 8 m, prune to a trunk diameter of 10 to 11 cm leaving 3 to 4 metres of green crown. The average pruned height should be about 4 metres. When the tree height is about 10-12 m (age 6-8) prune to a trunk diameter of 10 to 11 cm leaving 3-4 metres of green crown. This should achieve the target pruned height of 6.5 metres. On stressed or disease-prone sites do not prune below a trunk diameter of 11-12 cm. If necessary, return in about 12 months to prune smaller trees to the 6.5 metre target height. Typically prune 400 to 600 stems/ha in the first lift, decreasing to about 200 — 400 per hectare on the final lift.

Thinning

As the trees start to compete for light their diameter growth slows. The poorly formed trees should be thinned once the crowns begin to touch, and before the lower branches start to die and create dead knots. Thin at least twice as the crowns touch, until the trees are 12-15 metres high and pruned to 6-7 metres. Thinning should be aimed at getting a final crop of evenly spaced trees of between 200 and 600 stems per hectare depending on the target log diameter and rotation length.

When to harvest

Radiata grown for framing at 400-600 stems per hectare will usually reach an optimum harvest volume in 24-30 years. For clearwood, ideally radiata should be grown to 55–60 cm diameter over 30-35 years, to achieve an adequate sheath of clearwood. Radiata retains a core of low grade (“juvenile”) wood as it grows, and Irrespective of how big it looks it must be grown for more than 25 years to produce high value fibre. Even large young trees will yield mostly low-quality wood.

The wood has an even texture, a resinous fragrance, and is suitable for a wide variety of uses. It holds screws and nails well and takes paint, stain and glue without difficulty. Kiln dried timber machines easily, produces a smooth, clean surface and may be processed into a wide variety of moulding and timber profiles. Radiata is a feedstock for valuable engineering timbers like Laminated Veneer Lumber (LVL), Cross Laminated Timber (CLT) or laminated beams and columns. While it is not naturally durable radiata is easily treated for all Hazard Class applications. Treated, it is widely used in construction. Untreated, it is used for furniture, mouldings, trim and panelling. The woodchips are made into hardboard, softboard, particle board and MDF panels, newsprint and high grade packaging papers. Better logs may be peeled for veneers to make industrial and structural plywood. 

Markets and demand

Radiata pine is widely traded. About 15 million cubic metres per annum is processed in New Zealand and another 15 million exported as logs. Log prices are published regularly by the NZ Farm Forestry Association in its Market report.

Radiata grows vigorously and after two or three years can achieve height growth of more than a metre a year, and a diameter growth of 2-3 cm. Industry has developed the online Forecaster Calculator as a simple forest simulation tool that predicts tree growth and the log products per hectare that may result at any given clearfell age.

An earlier version called the Radiata calculator is available for download as an Excel spreadsheet.

Practical hints for measuring trees offers some advice on monitoring growth.

Radiata pine is listed on tables A2.2 and A2.4.

Timber return on investment

Timber return on investment varies widely, being affected by tree quality (management and stocking), harvesting costs and distance from markets. Including land costs but excluding carbon it may be 6 - 8% pa real (above inflation). A first rotation forest on land eligible for carbon credits could generate an early cash flow which would lift the apparent return, but it would not be a good indication of its long term profitability. The Forecaster Calculator might give a more useful indication of economics.

The authoritive leaflet NZFFA guide sheet No. 1: An Introduction to Growing Radiata Pine.

Scion has published a comprehensive Radiata pine growers manual which may be downloaded as a pdf file or purchased in hardcopy.