Category Archives: Management

Quilliam plantation update 2013

A recent phone call from Jamie Quilliam meant a return journey to Circular Head for some blackwood pruning and maintenance. I last reported on this plantation in October 2012:

But compared to 12 months ago this visit was a completely different experience. A year ago, to my complete surprise, this plantation was showing plenty of potential for commercial blackwood growth despite many obvious challenges. But this year the trees looked pretty unhappy with none of the strong apical growth seen 12 months ago. Had I misjudged the site? Was all that strong early growth just a flash in the pan?

Potential issues are the rainfall (last season was a dry one so there wouldn’t have been so much growth), and weed competition (trying to control grass growth on these wet flats is a real challenge!)

The first day of pruning was under a howling westerly wind, which confirmed that at least one of the challenges here is exposure. Blackwoods don’t enjoy growing on exposed sites, not if you want them to grow tall and straight.

On the second day we had finished the pruning and Jamie offered to show me the 3 hectare remnant patch of swamp forest which is next to one of the blackwood plantings. This remnant bush had cattle grazing through it until 13 years ago when it was fenced off. Since then the forest has recovered surprisingly well. From a distance I could see some very impressive Eucalyptus brookerana. But what surprised me most was as we got closer I began to notice the magnificent swamp blackwoods, 25-30 metres tall with long straight trunks (see picture). Clearly this farm used to support some fantastic blackwood swamp forest.


I suggested to Jamie that he would have more success growing commercial blackwood by actively managing the remnant bush. There is some regeneration but also opportunities for active management (eg. controlling blackberries) and blackwood planting. The lessons learnt in actively managing the remnant bush might then help solve the problems in the blackwood plantation. Jamie wasn’t sure about this idea. He hasn’t reached the stage of being passionate about growing blackwood, not yet anyway!

Obviously shelter and nursing from the surrounding vegetation is an important factor in native swamp-grown blackwood. But has conversion to pasture completely destroyed the commercial blackwood growing potential of this property? Here is the perfect opportunity to find out. Side by side, plantation blackwood and high quality native blackwood swamp forest. From the outset I realised that this property was an experiment in the making. Can we find a way to grow quality commercial blackwood in plantations on this property?

Blackwood Planting Time

It’s planting time. Is anyone thinking of planting commercial blackwood this autumn?

If so please let me know – I’d like to help.

It has been a very dry season so far. Unless we get some rain in the next few weeks it may be too dry to plant in some places this year.

Remember the first rule for successfully growing commercial blackwood is selecting the right site. If you are unsure I can help.

We can actually use the current dry season to help identify good sites. If your proposed planting site still has green grass then that is a very good sign that there is plenty of summer soil moisture. These sites are the best for getting good blackwood growth.

As for the planting regime my recommendation is to keep it simple. Until we gain more experience and confidence in growing commercial blackwood then keeping things as simple as possible is the best place to start.

If you are planting this autumn then your site preparation should be happening now:

1. Protection from browsing by all herbivores is very important. Unless your site is more than about 1 hectare in area, you will need tree guards for each tree. For larger areas you might consider mesh fencing. Work out the costings and see what is your cheapest option – tree guards or fencing.

2. Mark out your site with a 7 x 7 metre grid. This equates to 204 trees per hectare. With this tree spacing there will be no need to thin. Not every tree will survive or prosper with good management I would expect better than 80% success.

3. Do weed control in a 1 metre radius circle at each grid point.

4. You should now be ready to plant.

The best time to plant is from late March through to early May. Again, rainfall and soil moisture will be critical to watch in the coming weeks.

Commercial blackwood plantation – perfect land use and investment for that difficult, weed-covered slope.

Blackwood – An overview

Although this article is now 6 years old it is still a good summary of blackwood growing in New Zealand.
Ian Brown is coauthor of the New Zealand blackwood growers handbook. As a farmer his research has helped define the current success of blackwood in NZ.
His comment about blackwood growth rates in NZ compared vs Tasmania should not be taken too seriously.
Undoubtedly NZ has some very good sites for growing blackwood. But we have yet to really test the potential here in Tasmania.
Blackwood – An overview
New Zealand Tree Grower August 2006


Happy reading.

Helping blackwood stay on the straight and narrow


Research has shown, and certainly my own experience agrees, that blackwood growth rate and stem form are positively correlated. The faster the blackwood grows, the better the stem form and the less pruning is required to create a single straight-stemmed tree. Good growth rates are achieved by good site selection, good establishment techniques and good ongoing management.

But some pruning is inevitable. For a variety of reasons blackwood loses its growing tip and then goes on to develop multiple leaders that need to be managed. Here’s a recent example of form pruning to help keep these blackwoods on the straight and narrow. It’s not hard work, and can be enjoyable.

The following excerpt on blackwood pruning comes from the NZFFA website:


There has been an increasing acceptance that pruning is essential in managing blackwood. The method has no resemblance to pruning radiata pine; it is not difficult, but requires a commitment to visit the trees annually during the establishment of the 6 metre stem. There are two stages, which overlap:

·         form pruning

·         clearwood pruning

Form pruning

Blackwoods have poor apical dominance. Periods of stem growth are interrupted by abortion of the shoot tip. When growth resumes, several shoots compete for leadership. A blackwood stem is therefore formed by segments of straight growth which are interrupted by zones of disturbance which contain double or multiple leaders. The aim of form pruning is to identify and remove these competing leaders while they are still small (< 3cm diameter), and this requires an annual pruning visit during the formation of the 6 metre butt log. Long-handled pruners are useful.

Clearwood pruning

The aim is to confine the defect core. Clearwood pruning is done annually, starting at about year 3, and is complete by about year 8. It is carried out in stages, in which the largest branches on the stem are removed first, using a 3cm calliper. The trunk is then pruned to the diameter of your defect core (10 to 12cm). No more than a third of the foliage is removed at one visit. It is recommended that about 3 metres of the crown is left after each lift. Ladders that grip the trunk should not be used.

Perhaps not the best description of clearwood pruning. I would define the aim as controlling side branching, and then to progressively removing all branches from below to a height of 6 metres, while retaining about 3 metres of green live crown after each pruning.