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Growing Waratahs - A Few Tips PDF Print E-mail
Written by Darvill Nursery   
Sunday, 19 August 2012 16:11

Many people have a difficult time growing Waratahs in their garden, but many also are able to do so very successfully. I have even seen gardens with roses and waratahs growing beside each other. Then there are a few cut flower growers who grow thousands of them. With annual pruning the first five years or so they are able to get great vase shaped plants yielding between 300 to 500 blooms each. So what are the "secrets".

The following tips were extracted from a great book entitled ‘The Waratah’ (Paul Nixon, Kangaroo Press, 1997). It is full of valuable information on how to successfully grow Waratahs and get them to flower. The following are a few facts from the book (in no particular order) I found interesting:

The best soil for them is deep, free draining, with a north, north-east or north-west aspect to ensure maximum sun.

They usually grow 1 - 3 metres high and if in deep fertile soil free of competition, they will grow to 5 metres.

They normally commence flowering around the spring equinox in Sydney.

Once flowers have started to open, the bushes should be well watered, as stress at this time will cause added bract burn.

They are frost hardy to -12 degrees C.

The primary cultivation requirement is similar to the requirements of citrus: namely a well-drained site.

When planting, one sure method of achieving positive drainage is to place the plant on the ground or above ground surface - do not dig a hole but mound around the plant to form a bed. A grower I know has beds about 40 cm high and uses a root guard and ensures no weeds grow inside it.

They respond to very high levels of nutrition - especially Blood and Bone and farm manures (not fresh poultry manure). So be careful with ones with a high urea content.

The ideal NPK ratio for fertilisers is: N of 15-20%, P of about 2% and K of 5-10%.

Apply fertiliser to correspond with leaf growth - Spring and Autumn.

Pests - too many to list, but the main pest is the borer that attacks the ripening bud. Look out for sawdust at the base of the bud for sign of activity. Treat with a pesticide for borer in ornamentals.

Pruning juvenile Waratahs is desirable to make the plant divide and encourage basal growth.

In the wild, they flower best after bush fires as they are free from root competition for a few years at least. Lack of root competition in the home garden is recommended.

Flower buds develop early in the year, so it is in bud for 7 to 8 months.

Vase life of flowers is 10 to 14 days. To get an extra week pour a cup of water over the flower each day.

You can expect 500 flowers to a plant in ideal conditions, although 250 blooms is a more realistic total.

Fresh seed germinates readily. The seed deteriorates fairly rapidly unless stored at low temperature, low humidity and not in a plastic bag.


The following was also found in the NSW Waratah fact sheet produced by Mt Annan Botanic Gardens.

Transplant in autumn to a wind protected area.

Partial shade with morning sun is best, although Waratahs will grow in full sun.

Plant at lest 1.5 m apart or into very large pots.

Mulch soil with composted leaf mulch to prevent roots drying out.

Waratahs need regular watering. The roots should never be allowed to dry out, however they hate ‘wet feet’ - so ensure soil is free draining. It can be beneficial to mound topsoil -to 0.5 m high - and to incorporate leaf mulch into the soil.

Fertilize with a low phosphorus slow release fertilizer or ‘blood and bone’ in late winter or early spring.

Cultivated Waratahs require heavy pruning once established. About a third to half of the plant should be removed immediately after flowering to reinvigorate the plant. New shoots should flower the following year.

Waratahs flower in a six week period in spring in the Sydney region, but later in cooler areas.

The main pollinator of Waratahs are birds.

In our nursery we use a general native slow release fertiliser with about half the nitrogen coming from nitrate and ammonium salts. We normally grow our Waratah plants in pots (size dependent upon the plant size) with a good free draining soil mix (pH of 5.5 to 6), and under 50% shade to get large blooms.


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