Wollemi Pine seed propagation

Many Wollemi Pines in cultivation are now producing cones. This provides an opportunity for the home gardener to collect and sow their own seed.

Male and female cones

The Wollemi Pine is monoecious (i.e. male and female cones are borne on the same tree).
Male cones form in early to mid-summer and mature in spring when pollen is shed. If attempting hand pollination, the pollen must be fresh.
Female cones appear in mid to late summer (on higher branches) and they are pollinated in the following spring. Fertilisation happens approximately one year after pollination, several months prior to cone maturation, in late summer and early autumn, when seed and bract scale are shed.
You will notice that the timeline from observation of the male and female cones to collection of seeds is quite long, over several years!

When to collect

You want to collect the female cones before the seeds begin to disperse. So, in early summer you can either cover the cone with a seed bag or stocking or prune the branch itself from the tree.
As seeds begin to disperse, the cones begin to fall apart, so you do not want to miss the window, and have them all fall to the ground.
As the seeds gently flake away from the cone, it is time to sort through and select the viable seed for sowing.

Viable seeds – what they look like and how to test

Scrape the scale away from the seed using tweezers or your fingernail.
Fresh seeds that appear filled, have a taut seed coat, and do not depress under slight downward pressure from a fingernail are most likely viable.
Another test is to drop a seed onto a bench and listen; filled seeds will have a distinct sound.
Generally, less than 10% of the approximately 250 ovules in the female cones develop into viable seeds.
Seed should be used fresh, rather than stored.

Illustration of cone scale and seed. Credit: D Mackay (RBG Sydney).

Wollemi Pine seed (left) and bract scale (right).

Wollemi Pine empty seed (left) and filled seed (right).

Seed germination

Use a premium grade seed mix that is certified to meet the Australian Standards or equivalent.

Choose a punnet or tray for sowing seeds:
- A multi cell seedling punnet enables you to sow individual seeds in each cell and provide enough depth to let it grow on for at least six months.
- Alternatively, a seedling tray means sowing all the seed together and then pricking them out individually when they are large enough to pot up. These shallow trays run the risk of misshaping the radicles and primary roots, as well as overcrowding; which leads to leggy growth.
Press your finger into the seed mix to make an indentation of 5mm.
Place the seed in laying sideways.
Gently cover the hole over with mix and water in well.
Do not allow the mix to dry out; keep moist but not soggy. It may just need a daily misting.

Note: Wollemi Pine seeds exhibit non-deep physiological dormancy, which can be relaxed by cold stratification for several weeks at less than 10°C (Offord and Meagher 2001). These conditions are believed to mimic the fall of ripe seeds in late summer, their exposure to moist cold conditions in winter and germination in spring and summer (Offord and Meagher 2001). To mimic these conditions, you can try the following:

Cold stratification - store the moistened sown seed punnets in a large plastic bag for 2 weeks in your fridge. This can be beneficial to the germination rate and encourages a more uniform germination period.