Growing Waratahs

Waratahs, being Australia’s plant emblem, have always attracted me. Early in my gardening career I purchased two Telopea speciosissima plants consecutively. Both died very quickly and I gave up trying just as quickly. I realise that my garden soil, being clay-based, did not provide a promising planting medium. I have enjoyed seeing waratahs in bloom in Leura domestic gardens and also in the rocky heights above the sea entrance of the Hawkesbury River.

How could I make it possible for a waratah to grow in my garden?

I have been advised that waratahs have a central root which may be able to penetrate my clay soil; that they also have surface roots which can support the tap root. I have also heard the suggestion that hybrid Australian plants have vigour that exceeds that of the primary species.

My first step was to purchase a plant from a local nursery: Telopea speciosissima × monganensis.

The second step was to take about six bags of planting mix and make a mound into which I planted my purchase with a cupped surface around it to capture water. I watered thoroughly with seaweed mixture.

The plant was watered several times in the first week and then more sparingly. It responded very well: within a month new shoots thrust out. I was happy.

Around three months later I noticed a yellowing of the leaves with the main sap deliverers remaining green. I watered it with seaweed mixture and hoped.
In about one month the plant was dead.

What did I do wrong? Is it impossible to grow waratahs in anything but sandy soil?
Can you please help me?

— Ian Cox – May 2025 Calgaroo

In the last Calgaroo (April 2025), Grahame Forrest told us about his failed attempts at growing the NSW Waratah (Telopea speciosissima), and asked members for advice.

I, too, have trouble growing Waratahs, and have given up. So, what should we do?? Look up Google, of course!

This is what ‘reliable Google’ says:

Botanic Gardens of Sydney
Partially shaded with morning sun is best, although Waratahs will grow in full sun.
In the Southern Hemisphere, Waratahs will not survive on south-facing walls. Transplant in autumn to a wind-protected area if needed.
Waratahs are poor competitors and will not perform well close to most eucalypts.

Gardening with Angus
Waratahs grow well on sandy loam with good drainage, and with supplementary watering if conditions are very dry.
They like good airflow around them, so don’t place them too close to other plants.
Plant in light shade or half shade. pH level should be acid to neutral.

Gardening Australia (Costa)
They like a nice protected position away from the hot western sun and wind.
The soil needs to be constantly moist, but well-drained and acidic. They can be grown in crushed sandstone.
Only use native fertiliser with little or no phosphorus.
If you get some blooms, do a little dance and congratulate yourself, because that’s a great achievement!

Australian National Botanic Gardens
Waratahs appreciate a friable soil of good texture. The incorporation of a rich leaf compost or similar material is beneficial. If other soil is added to the site, always incorporate it into the existing soil. Do not excavate a large hole and then fill it with a good soil mix, as water will accumulate in the hole, resulting in wet feet and probable plant death.
Good drainage and aeration are essential, and if possible, should extend to a depth of 45 cm. Drainage can be improved by building a raised bed or mound. If this is done, be sure to break the existing soil where the mound is to be located so that the new soil can be incorporated with the existing soil.
Watering can be carried out during hot or dry spells. Never let the soil dry out completely. Over-watering in heavy soils will cause waterlogging.
Waratahs appear to be adaptable to various situations, but a semi-shaded position or at least shade from afternoon sun is desirable.
Mulch the surrounding soil to a depth of 5–6 cm. This will help to keep the soil moist and keep the surface roots cool. Mulch also helps to prevent weed growth in the vicinity of the plant. If weeds are allowed to grow, they provide direct competition to the plant for nutrients and water. Removal of weeds may also disturb the surface roots and result in setback of the plant.
Plant where it can receive plenty of air circulation and room in which to grow.

Grahame has clay soil, so the above advice probably hasn’t helped him much. But the strange thing is that I have sandy acidic soil, and Waratahs grow naturally in the next gully to here. But they still die when I plant them!
What will I do? Hmmmm . . . should I try again, using some of these Google tips?
I’m not sure yet.