Sand is a difficult place for plants to survive, but some plants have managed to adapt to the environment and play an important role in the creation of sand dunes.
Dune plants are tough critters, surviving salt spray, being flooded by sea water during storms, living on shifting sand, and trying to hang on to precious fresh water that rushes through the sand. They survive high temperatures, low nutrients, and fierce winds.
The New Zealand Forest Research Institute (Private Bag 3020, Rotorura)
is working with community dune care groups, the Department of
Conservation, and Regional and local councils to help rebuild
New Zealand's coastal plants and manage the dune environment.
They conduct research into replanting and harvesting of Pingao,
Spinifex and other coastal plants.
Pingao is replanted on dunes using nursery-raised seedlings.
Seeds are collected in late December to early January. Collect
them after they have ripened and are a golden brown. You will
find a few husks on the sand when they are ready. They should
easily fall from the husk when rubbed. If the seed is still green
it should not be collected. Clip the entire seed head from the
plant and put it in a strong plastic bag. Collect from a variety
of plants and leave some seed heads on each plant to provide natural
Later, to remove the seeds, place the seed head in a tray out
of the wind, but exposed to the sun. After a few days, put the
seeds and husks in a bowl and stir them. The husks will rise to
the surface and most can be removed from the seeds.
Put the dried seeds in a plastic bag, seal it well, and put them
in your refrigerator. Don't let them freeze. They can stay in
a refrigerator no longer than a year. Remove the seed from the
plastic bag and soak them in water in early August or September.
Drain the water and mix the seed with 3 or 4 times its volume
of moist peat.
Seal the seed and peat in a plastic bag with small holes to allow
air movement. Replace this in the refrigerator for about 4 weeks.
If the seeds germinate, remove them and sow them immediately.
Sow the seeds in wood or plastic seed trays with ventilation holes
on the base. Use a lightly compacted seed raising mix of 50% sand
and 50% peat. Spread the sead/moist peat mix evenly over the surface
and cover with a thin layer of coarse sand. Water the seed tray
two or three times a day. Put the trays on sand to allow drainage
and prevent waterlogging. The trays should be kept at 15 to 25
degrees C in a glasshouse or conservatory.
The seeds germinate within 4 to 7 weeks. Allow them to grow to
6 or 8 cm high before transplanting to Rootrainer containers.
If rootrainers are not available, use propagation tubes or even
yoghurt pots. Allow the seeling's roots to descend vertically
and fully into the pottong mix. Use a pencil or stick to carefully
adjust the roots in the container.
The potting mix should be 25% to 50% coarse pumice or coarse washed
sand. this imporves drainage and prevents waterlogging. Use peat
and potting mix grade bark for the remainder. Be sure the peat
and bark are well decomposed to prevent heating of the soil by
Fertilise with a controlled release capsule such as Osmocote Plus
at about 2.5kg per cubic metre of potting mix. 1 to 1.5 kg of
dolomite lime can be added per cubic metre of mix and 1 kg of
Keep in a glasshouse for 4 to 6 weeks. Watering must be regular
and temperatures must be below 30 degrees C. The plant containers
should be on freely draining survaces such as sand. After 4 to
6 weeks, shift the seedlings to a shaded area.
Plant in the autumn. Move the plants to an exposed site, with
full sun and strong winds at least 8 weeks before planting. The
plants will change colour from green to golden brown.
Seedlings planted on small, exposed, unstable foredunes with sparse
vegetation survive much better than those planted on stabilised,
They are planted in groups of 25-30 seedlings at 50X50-cm spacing.
Slow-release NPK fertiliser at 30g per plant is mixed with the sand when the seedling is planted.
Spinifex (Spinifex sericeus) or kowhangatara, is more common
than pingao and is also important in creating and maintaining
Unlike pingao, spinifex is difficult to grow in nursery from seed
and is usually spread by direct seeding and transplanting of cuttings.
Trials are continuing at the New Zealand Forest Research Institute
for the best methods and times for planting. Initial trials suggest
that a high nitrogen fertiliser improves survival and growth.
Wild seeds are sowed in holes 100-mm deep.
Cuttings of runners 600-mm long are put into 200-mm deep trenches
with the runner tips exposed.
Restoration of native plant communities on sand dunes. Bergin and Herbert 1994. What's new in Forest Research. No. 232. New Zealand Forest Research Institute, Private Bag 3020, Rotorua.
Pingao: seed collection and propagation. by Roger MacGibbon (Native plant specialist).