Wollemi Pine (Wollemia nobilis)

Wollemia nobilis

We suggest using a well-balanced controlled-release fertiliser suited for general tree growth. An ideal nutrient ratio would be 15 – 4 – 9 (N-P-K) with trace elements. Apply annually in early spring. You can also supplement this with fortnightly liquid feeds as a soil drench or foliar feed during the active growth periods.

We also recommend biostimulant products, including humic and fulvic acids, seaweed extracts, and beneficial bacteria and fungi. These improve the microbial activity of the soil, nutrient uptake and efficiency, increase tolerance to environmental stressors and encourage the production of plant defence compounds.

Wollemi Pines prefer shade (especially young), protection from the wind and a cool root run.

Various websites state that they can be grown in exposed sites with full sun; this is true to a certain extent but be aware that they may be subject to leaf scorch and wind burn. The nature of an “exposed site with full sun” will vary from place to place and between the northern and southern hemispheres – in some areas; it may be too hot and dry for Wollemi Pines to thrive.

This species prefers acid soil; in their natural habitat, the soil pH is as low as 4, and in cultivation, you should aim for a pH of less than 6. You can test your soil pH with a store-bought testing kit. To lower soil pH, use granular sulphur (following application rates as per your soil type) and incorporate more organic material into your soil. Note that sulphur works slowly, taking approximately six months to alter the pH. The soil should be organically rich, moisture retentive and well-draining. Planting on a slight slope is ideal for enhancing draining capacity.
It is best to plant your specimen in either spring or autumn.

The Wollemi Pine grows equally well as a garden or potted specimen. The growth rate is slightly slower in a pot, but it can be maintained easily and for many years. Suppose your garden cannot provide the optimum growing environment (consider the aspect, climate and soil), or you don’t have a garden you can plant. In that case, you can still grow a healthy specimen on a patio or in a courtyard in a pot. Whilst it is possible to grow indoors, be aware that it will never look its best in an air-conditioned environment.

Early spring is the best time for repotting before your Wollemi Pine has pushed out its new flush of branches. The fresh soil and slow-release fertiliser will aid and boost this season’s recent growth. Repotting once the new branches have opened is a little trickier; the new growth is very soft and easily damaged.

Repotting has more to do with root mass than the exact height of your tree. A simple squeeze test of the pot (if you are using a plastic pot) informs you whether it is time to re-pot: If the pot is very firm and difficult to squeeze, then the roots have already reached the edge and base of the pot. If it is easy to squeeze and you can feel a lot of movement in the soil, the roots are still catching up to fill the soil volume, and you can wait another year.

On average, you can expect to re-pot Wollemi Pines every two years. However, growers who apply a constant liquid feed may need to re-pot annually.

Select a premium potting mix that is certified to meet Australian Standards. This should not be a potting mix suitable for Australian native species, as these are too low in phosphorus. Selecting an ericaceous mix ensures that it will be more acidic; these mixes will be labelled as suitable for Azaleas, Rhododendrons or Camellias. You can add some controlled release fertiliser to your mix, or as a top dressing once you have repotted the plant.

Do not be tempted to plant into a pot that is very large compared to the size of the root mass! You may consider it a time-saver, but it runs the risk of root rot. If the tree is sitting in a large volume of new soil, there will be more water held than the roots can take up. This reduced aeration means the roots are effectively drowning. Going up one standard pot size should suffice, two sizes up are the maximum advised, for example, from 175mm to 200mm in diameter, or 200mm to 250mm.

To maintain a high-quality root system, root management is a critical step in the repotting process. Without it, you may end up with circling or bent roots. Root defects can lead to reduced vigour, growth rate and stability. This is extremely pertinent if you plan to plant your tree in the ground. Often upon inspection, you will need to carry out some basic root pruning.

Roots will often grow to the edge or base of the pot, then deflect down, up and around the periphery of the root ball, forming a type of shell. “Shaving” and pruning the shell on the periphery and bottom of the root ball will eliminate most of the defects. Root defects should be removed at the point just behind the bend in the root. New roots will typically grow from behind the cut in a fanlike pattern away from the trunk. Sharp, disinfected knives and secateurs are the best tools for this job.

Planting too deeply can also cause defects at the root collar, so ensure the root collar is just below the surface when you re-pot.