Garden advice Q&As – more from our experts

By Glenda Browne

Glenda Browne summarises recent queries about gardening with natives sent to our office email. Our group of experts responds.

Wildlife: Blue wrens

Q: Could you advise the best approach to making a garden that is enticing to blue wrens.

A: To encourage small birds like blue wrens in your garden you need to plant some low shrubs to provide them with shelter. There are small grevilleas, tea trees, paperbarks and bottlebrushes that provide shelter for birds. 

Our plant database has profiles on shrubs less than 1 m here.

Plant care: Firewheel tree with brown-tipped leaves (Stenocarpus sinuatus)

Q: We have a firewheel tree that is not looking very happy. In February and March this year the tree was looking healthy but throughout winter many dead branches with seed pods have appeared and the remaining leaves have brown tips. There are small sections with green leaves but not many. We are wondering whether we need to cut it back or feed it with anything in particular?

A: From your photos I can see a majority of green leaves suggesting that there is not a lot wrong with your firewheel tree. There is some dieback amongst some of the small branchlets. These could be pruned to give the tree a better appearance. A brown tip to each leaf is of concern if it is all over the tree. You could apply a general fertiliser if you wish.

Plant care: Pruning Port Jackson Pine (Callitris rhomboidea)

Q: Can I can prune the Port Jackson Pine so it stays dense at a lower level?

A: Port Jackson Pine (Callitris rhomboidea) can be pruned to shape. It has been used as a hedging plant. Prune from the top so it will be a lower-shaped shrub rather than a pine-shaped tree. Read about the plant here.

Shows seedpods
Callitris rhomboidea

Soil mixes

Q: I’m about to plant a few natives, some grevilleas, banksias, mini lilli pillis. I live in the Shoalhaven, our soil is very poor –  30 cm of topsoil, then clay.  There are several different brands of soil mixes on offer locally, all have about 30-40%  organic compost with river sand and soil. Could you make any recommendations on improvements to this mix?

A: One respondent wished that he had 30 cm of topsoil! The chosen mix would depend on the actual species you’d want to grow. For example, some banksia species thrive on poor, thin soil on sandstone.

A mix containing 30% sand will drain well with the balance made up of soil/organic matter.  Ideally the mix should be mounded to half a metre to aid drainage. It is possible to buy Australian Standard soil potting mix. Another way to improve clay is by adding gypsum to the soil. If you are using a prepared soil mix, then you would want a one that does not have fertilisers added. It is safer to add your own, as native plants, particularly grevilleas and banksias, need fertilisers that are low in phosphorus.

There are many native plants that are quite happy in clay soils, so some potential problems can be avoided by good plant selection. It was also suggested that plants have to become accustomed to the environment in which they have been planted, rather than always having to improve the environment to suit the plant.

The following page from the Central Coast APS group provides a useful summary for dealing with clay soils and some suggested plants – https://austplants.com.au/Central-Coast-Resources


Thanks to John Aitken, Mark Abell, Ralph Cartwright, Rhonda Daniels, Alix Goodwin, Heather Miles, John Nevin, Merle Thompson, Dick Turner and our external correspondents.

Read more

Read more answers from our experts group to queries about native plants  here, here and here.