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Banksias for Your Garden

 

Banksias are some of our most spectacular flowering Australian plants, ranging from ground hugging shrubs to small trees. 

The leaves of banksias are usually hard and leathery with toothed margins or edges.

 The flowers are produced in a dense compact spike. On each flower spike, the individual flowers can number in the thousands.

Nectar feeding birds are attracted to these flowers, whilst cockatoos and parrots will eat the seeds in the fruiting cones. Banksias flower from late summer through to spring and form an important part of the food chain.

 

 

Banksia integrifolia

 

 

 

 

 

 

 

 

Where should I grow Banksias?

  • Banksias require an open sunny position in a soil with very good drainage

    If the soil has high clay content, then raised beds of sandy loam and coarse river sand will give better results.
     

  • Banksias resent soil temperature and moisture fluctuations. By using ground covering plants or a sand or gravel mulch this can be avoided. Wood chip or pine bark mulches may retain too much moisture. Natural bush litter mulch may contain root rotting fungal spores.
     

  •  Banksias are very susceptible to cinnamon fungus Phytophthora cinnamomi, a root rotting fungus. An infected plant can still appear healthy, until a period of stress occurs, when it can literally die overnight. Poor drainage, excessive moisture and hot weather are the perfect conditions for this fungus to spread.

Can I grow Western Australia Banksias?

  • Many of the spectacular Western Australian species are intolerant of our wet and humid summers, and can succumb to the root rotting fungus Phytophthora cinnamomi.
     

  • To grow these species it is recommended that better results can be achieved by growing grafted plants. These are available at specialist nurseries.
     

  • As grafting techniques improve more species will become available.

What type of fertilizer should I use?

  • Banksias require a low phosphorus fertilizer, so use a slow release low phosphorus fertilizer that is recommended for native plants.
     

  • Using large amounts of fertilizer should be avoided as most species have evolved in low fertility soils.
     

  • Some species may start producing yellow new leaves. This may be caused by a deficiency of either iron or nitrogen. This can be rectified by applying iron chelates or a nitrogenous fertilizer.
     

  • Regular watering will help establish young plants during the first 12 to 18 months. Watering should be slow and soaking to thoroughly wet the soil to encourage the plant to develop a deep penetrating root system. Water during cooler weather to reduce the risk of fungal attack.

Should I prune my banksias?

Most banksias respond to regular light pruning and this can be in the form of cutting flowers for floral decorations. Heavy pruning can result in excessive leaf growth at the expense of flower production. Cutting back into old wood may result in no new re-growth.

Can banksias be grown from seed?

All Banksia species can be grown from seed. Heat is usually needed to extract the seed from the mature cones. Place the cone in a 100C oven for approx 30 minutes to release the seed. Each follicle contains 2 seeds with wispy wings attached. These seeds can then be sown and kept moist, until germination occurs. Selected forms should be grown from cuttings.

What are the local Banksia species?

Banksia ericifolia - Heath Banksia

A dense shrub to 7m tall, flowering in the autumn and winter with orange–red flower spikes up to 30cm tall. The leaves are small, 2cm x 0.3cm green above with silver beneath.  A useful screening shrub, adapting to a variety of soil conditions, but will not tolerate wet feet. There are several forms available with different coloured flowers, for example burgundy or red flowers. There is also a dark purplish form. Nectar feeding birds are attracted at flowering times.

 

 

Banksia spinulosa var. spinulosa     

Hairpin Banksia    

 

 

 

 

An open spreading shrub to 3m tall with long narrow leaves and a serrated margin. Flower spikes are up to 15cm tall, bright golden colour with blue-black hooked styles. Flowering during autumn and winter.

Banksia spinulosa is found growing as an under story shrub in dry sclerophyll forests. Hardy in most situations except poorly drained soils and heavy shade.

There are a number of selected forms of Banksia spinulosa available at nurseries these include-

  • Banksia ‘Birthday Candles’. A dwarf shrub to 1m with bright yellow flowers in autumn and winter.
     

  • Banksia ‘Honeypots’ A low growing shrub to 0.60cm With honey coloured flowers in autumn to early spring.
     

  • Banksia spinulosa Dwarf Red Form. Varying shades of red in the flowers. 

 Banksia ‘Giant Candles’ is a hybrid between B. ericfolia and B.spinulosa

It produces 40cm long deep orange flower spikes during autumn through to early spring. ‘Giant Candles’ can grow to 5m.tall with a spread of 3m.

Banksia marginata - Silver Banksia.

Depending upon growing conditions the silver banksias can range from a small shrub of 1m to a small tree of about 8m. The leaves are green above with a silver-white underside. The short flower spikes are yellow and rich in nectar.

Banksia marginata is very adaptable to a large range of soils and climatic conditions.

 

Banksia integrifolia. Coast Banksia

This is a common species along our sandy beaches growing to around 10m tall. The leaves are a dull green with a silver-white reverse. The flowers are small, 5-12cm long and pale yellow, occurring from autumn through to spring.

Banksia robur - Swamp Banksia.

An upright shrub to 2m with large leathery leaves. The flower buds are bright green with the appearance of having  been sculptured, opening to a creamy yellow flower. The swamp banksia will grow in poor soils and will tolerate periodic wet feet. Hardy under most conditions.

Banksia serrata.- Old Man Banksia.

A rough bark tree with a gnarled appearance, tough leathery leaves and shaggy old flowers, gives this banksia its common name.

The developing buds are a blue-grey colour, with the flowers opening to a yellowish green.

Banksia serrata is an excellent small tree for attracting nectar feeding birds. with occasional flowers throughout the year.

There are a number of selected forms available, for example a prostrate form which makes an excellent ground cover in an open sunny position. Coast banksias can be useful plantings for beach care restoration programs, but will also grow on heavier soils.

Adaptable to exposed sites but responds with extra water during dry periods.

 

Produced by the Australian Plants Society, Central Coast Group in conjunction with Gosford City Council and Wyong Shire Council.
Australian Plant Society, Central Coast Group Web site:
www.australianplants.org